Append a record to the end of a text file: Difference between revisions
Line 2,157: | Line 2,157: | ||
for rec in records: |
for rec in records: |
||
echo str(rec) |
echo str(rec) |
||
echo "" |
|||
# Add a new record at the end of password file. |
# Add a new record at the end of password file. |
||
Line 2,171: | Line 2,170: | ||
echo "---------------------" |
echo "---------------------" |
||
echo str(newRecord) |
echo str(newRecord) |
||
echo "" |
|||
if pwfile.getLock(): |
if pwfile.getLock(): |
||
pwFile.writeLine(newRecord) |
pwFile.writeLine(newRecord) |
||
Line 2,209: | Line 2,207: | ||
directory: /home/jdoe |
directory: /home/jdoe |
||
shell: /bin/bash |
shell: /bin/bash |
||
Appending new record: |
Appending new record: |
||
Line 2,220: | Line 2,217: | ||
directory: /home/xyz |
directory: /home/xyz |
||
shell: /bin/bash |
shell: /bin/bash |
||
Raw content of updated password file: |
Raw content of updated password file: |
Revision as of 21:12, 15 October 2020
![Task](http://static.miraheze.org/rosettacodewiki/thumb/b/ba/Rcode-button-task-crushed.png/64px-Rcode-button-task-crushed.png)
You are encouraged to solve this task according to the task description, using any language you may know.
Many systems offer the ability to open a file for writing, such that any data written will be appended to the end of the file. Further, the file operations will always adjust the position pointer to guarantee the end of the file, even in a multitasking environment.
This feature is most useful in the case of log files, where many jobs may be appending to the log file at the same time, or where care must be taken to avoid concurrently overwriting the same record from another job.
- Task
Given a two record sample for a mythical "passwd" file:
- Write these records out in the typical system format.
- Ideally these records will have named fields of various types.
- Close the file, then reopen the file for append.
- Append a new record to the file and close the file again.
- Take appropriate care to avoid concurrently overwrites from another job.
- Open the file and demonstrate the new record has indeed written to the end.
account | password | UID | GID | fullname,office,extension,homephone,email | directory | shell |
---|---|---|---|---|---|---|
string | string | int | int | struct(string,string,string,string,string) | string | string |
jsmith | x | 1001 | 1000 | Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org | /home/jsmith | /bin/bash |
jdoe | x | 1002 | 1000 | Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org | /home/jdoe | /bin/bash |
account | password | UID | GID | fullname,office,extension,homephone,email | directory | shell |
---|---|---|---|---|---|---|
string | string | int | int | struct(string,string,string,string,string) | string | string |
xyz | x | 1003 | 1000 | X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org | /home/xyz | /bin/bash |
Resulting file format: should mimic Linux's /etc/passwd file format with particular attention to the "," separator used in the GECOS field. But if the specific language has a particular or unique format of storing records in text file, then this format should be named and demonstrated with an additional example.
Expected output:
Appended record: xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Finally: Provide a summary of the language's "append record" capabilities in a table. eg.
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
C struct | CSV text file | glibc/stdio | ☑ | ☑ | ☑ (Not all, eg NFS) |
Alternatively: If the language's appends can not guarantee its writes will always append, then note this restriction in the table. If possible, provide an actual code example (possibly using file/record locking) to guarantee correct concurrent appends.
AWK
<lang AWK>
- syntax: GAWK -f APPEND_A_RECORD_TO_THE_END_OF_A_TEXT_FILE.AWK
BEGIN {
fn = "\\etc\\passwd"
- create and populate file
print("account:password:UID:GID:fullname,office,extension,homephone,email:directory:shell") >fn print("jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash") >fn print("jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash") >fn close(fn) show_file("initial file")
- append record
print("xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash") >>fn close(fn) show_file("file after append") exit(0)
} function show_file(desc, nr,rec) {
printf("%s:\n",desc) while (getline rec <fn > 0) { nr++ printf("%s\n",rec) } close(fn) printf("%d records\n\n",nr)
} </lang>
Output:
initial file: account:password:UID:GID:fullname,office,extension,homephone,email:directory:shell jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash 3 records file after append: account:password:UID:GID:fullname,office,extension,homephone,email:directory:shell jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash 4 records
Batch File
<lang dos> @echo off
(
echo jsmith:x:1001:1000:Joe Smith,Room 1007,^(234^)555-8917,^(234^)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash echo jdoe:x:1002:1000:Jane Doe,Room 1004,^(234^)555-8914,^(234^)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash
) > append.txt
echo Current contents of append.txt: type append.txt echo.
echo xyz:x:1003:1000:X Yz,Room 1003,^(234^)555-8913,^(234^)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash >> append.txt
echo New contents of append.txt: type append.txt pause>nul </lang>
- Output:
Current contents of append.txt: jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash New contents of append.txt: jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
C
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
C struct | CSV text file | glibc/stdio | ☑ | ☑ | ☑ (Not all, eg NFS) |
Note: Not all File Systems support atomic appends. In particular NFS does not. It is not known if there is a standard OS independent way of detecting if atomic appends are available. However most Unix & Linux File Systems do support atomic appends, especially for log files.
From a C "struct" to CSV File <lang C>#include <stdio.h>
- include <string.h>
/* note that UID & GID are of type "int" */ typedef const char *STRING; typedef struct{STRING fullname, office, extension, homephone, email; } gecos_t; typedef struct{STRING account, password; int uid, gid; gecos_t gecos; STRING directory, shell; } passwd_t;
- define GECOS_FMT "%s,%s,%s,%s,%s"
- define PASSWD_FMT "%s:%s:%d:%d:"GECOS_FMT":%s:%s"
passwd_t passwd_list[]={
{"jsmith", "x", 1001, 1000, /* UID and GID are type int */ {"Joe Smith", "Room 1007", "(234)555-8917", "(234)555-0077", "jsmith@rosettacode.org"}, "/home/jsmith", "/bin/bash"}, {"jdoe", "x", 1002, 1000, {"Jane Doe", "Room 1004", "(234)555-8914", "(234)555-0044", "jdoe@rosettacode.org"}, "/home/jdoe", "/bin/bash"}
};
main(){ /****************************
- Create a passwd text file *
- /
FILE *passwd_text=fopen("passwd.txt", "w"); int rec_num; for(rec_num=0; rec_num < sizeof passwd_list/sizeof(passwd_t); rec_num++) fprintf(passwd_text, PASSWD_FMT"\n", passwd_list[rec_num]); fclose(passwd_text);
/********************************
- Load text ready for appending *
- /
passwd_text=fopen("passwd.txt", "a+"); char passwd_buf[BUFSIZ]; /* warning: fixed length */ passwd_t new_rec = {"xyz", "x", 1003, 1000, /* UID and GID are type int */ {"X Yz", "Room 1003", "(234)555-8913", "(234)555-0033", "xyz@rosettacode.org"}, "/home/xyz", "/bin/bash"}; sprintf(passwd_buf, PASSWD_FMT"\n", new_rec);
/* An atomic append without a file lock,
Note: wont work on some file systems, eg NFS */ write(fileno(passwd_text), passwd_buf, strlen(passwd_buf)); close(passwd_text);
/***********************************************
- Finally reopen and check record was appended *
- /
passwd_text=fopen("passwd.txt", "r"); while(!feof(passwd_text)) fscanf(passwd_text, "%[^\n]\n", passwd_buf, "\n"); if(strstr(passwd_buf, "xyz")) printf("Appended record: %s\n", passwd_buf);
}</lang>
- Output:
Appended record: xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
C#
<lang csharp>using System; using System.IO;
namespace AppendPwdRosetta {
class PasswordRecord { public string account, password, fullname, office, extension, homephone, email, directory, shell; public int UID, GID; public PasswordRecord(string account, string password, int UID, int GID, string fullname, string office, string extension, string homephone, string email, string directory, string shell) { this.account = account; this.password = password; this.UID = UID; this.GID = GID; this.fullname = fullname; this.office = office; this.extension = extension; this.homephone = homephone; this.email = email; this.directory = directory; this.shell = shell; } public override string ToString() { var gecos = string.Join(",", new string[] { fullname, office, extension, homephone, email }); return string.Join(":", new string[] { account, password, UID.ToString(), GID.ToString(), gecos, directory, shell }); } } class Program { static void Main(string[] args) { var jsmith = new PasswordRecord("jsmith", "x", 1001, 1000, "Joe Smith", "Room 1007", "(234)555-8917", "(234)555-0077", "jsmith@rosettacode.org", "/home/jsmith", "/bin/bash"); var jdoe = new PasswordRecord("jdoe", "x", 1002, 1000, "Jane Doe", "Room 1004", "(234)555-8914", "(234)555-0044", "jdoe@rosettacode.org", "/home/jdoe", "/bin/bash"); var xyz = new PasswordRecord("xyz", "x", 1003, 1000, "X Yz", "Room 1003", "(234)555-8913", "(234)555-0033", "xyz@rosettacode.org", "/home/xyz", "/bin/bash");
// Write these records out in the typical system format. File.WriteAllLines("passwd.txt", new string[] { jsmith.ToString(), jdoe.ToString() });
// Append a new record to the file and close the file again. File.AppendAllText("passwd.txt", xyz.ToString());
// Open the file and demonstrate the new record has indeed written to the end. string[] lines = File.ReadAllLines("passwd.txt"); Console.WriteLine("Appended record: " + lines[2]); } }
} </lang>
- Output:
>AppendPwdRosetta.exe Appended record: xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
C++
<lang cpp>#include <iostream>
- include <fstream>
- include <string>
- include <vector>
std::ostream& operator<<(std::ostream& out, const std::string s) {
return out << s.c_str();
}
struct gecos_t {
std::string fullname, office, extension, homephone, email;
friend std::ostream& operator<<(std::ostream&, const gecos_t&);
};
std::ostream& operator<<(std::ostream& out, const gecos_t& g) {
return out << g.fullname << ',' << g.office << ',' << g.extension << ',' << g.homephone << ',' << g.email;
}
struct passwd_t {
std::string account, password; int uid, gid; gecos_t gecos; std::string directory, shell;
passwd_t(const std::string& a, const std::string& p, int u, int g, const gecos_t& ge, const std::string& d, const std::string& s) : account(a), password(p), uid(u), gid(g), gecos(ge), directory(d), shell(s) { //empty }
friend std::ostream& operator<<(std::ostream&, const passwd_t&);
};
std::ostream& operator<<(std::ostream& out, const passwd_t& p) {
return out << p.account << ':' << p.password << ':' << p.uid << ':' << p.gid << ':' << p.gecos << ':' << p.directory << ':' << p.shell;
}
std::vector<passwd_t> passwd_list{
{ "jsmith", "x", 1001, 1000, {"Joe Smith", "Room 1007", "(234)555-8917", "(234)555-0077", "jsmith@rosettacode.org"}, "/home/jsmith", "/bin/bash" }, { "jdoe", "x", 1002, 1000, {"Jane Doe", "Room 1004", "(234)555-8914", "(234)555-0044", "jdoe@rosettacode.org"}, "/home/jdoe", "/bin/bash" }
};
int main() {
// Write the first two records std::ofstream out_fd("passwd.txt"); for (size_t i = 0; i < passwd_list.size(); ++i) { out_fd << passwd_list[i] << '\n'; } out_fd.close();
// Append the third record out_fd.open("passwd.txt", std::ios::app); out_fd << passwd_t("xyz", "x", 1003, 1000, { "X Yz", "Room 1003", "(234)555-8913", "(234)555-0033", "xyz@rosettacode.org" }, "/home/xyz", "/bin/bash") << '\n'; out_fd.close();
// Verify the record was appended std::ifstream in_fd("passwd.txt"); std::string line, temp; while (std::getline(in_fd, temp)) { // the last line of the file is empty, make sure line contains the last record if (!temp.empty()) { line = temp; } } if (line.substr(0, 4) == "xyz:") { std::cout << "Appended record: " << line << '\n'; } else { std::cout << "Failed to find the expected record appended.\n"; }
return 0;
}</lang>
- Output:
Appended record: xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
COBOL
COBOL is a record oriented language. Commonly referred to as ISAM, Indexed Sequential Access Mode IO, is the main type of file operations with COBOL, but that is never quite technically correct as there can be various file handling subsystems included with a COBOL installation.
GnuCOBOL supports ISAM for SEQUENTIAL, RANDOM and INDEXED file organizations, that can be accessed with SEQUENTIAL, RANDOM and DYNAMIC modes.
LINE SEQUENTIAL access (an extension to standard COBOL) is also supported for "normal" newline delimited text files. The GnuCOBOL compiler source kit ships with a choice of four different file subsystem configurations, as well as allowing external site defined handlers during compiler builds. So, even though it is a common expression, ISAM is rarely a complete or technically correct statement. IBM COBOL dialects support a wide variety of mainframe file access subsystems, for instance.
With GnuCOBOL, normal text file operations rely on the POSIX layer, and have features very similar (or identical) to the technical interface enjoyed by C.
OPEN EXTEND provides automatic file appends. OPEN I-O allows for program controlled appends with START LAST, READ NEXT and READ PREVIOUS positioning control, paired with WRITE and REWRITE statements.
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
Record hierarchy | text file | POSIX | ☑ | ☑ | ☑ (Not all, eg TAPE devices) |
Record hierarchy | SEQUENTIAL | POSIX/ISAM | ☑ | ☑ | ☑ (Not all) |
Record hierarchy | RANDOM | POSIX/ISAM | ☑ | ☑ | ☑ (Not all) |
Record hierarchy | INDEXED | ISAM | ☑ | ☑ | ☑ (Not all) |
Note: Not all File Systems support atomic appends. In particular NFS, and many TAPE devices do not. Guaranteed atomic append operations will be highly dependent on file handling subsystem and device capabilities.
Record group to passwd format, LINE SEQUENTIAL <lang COBOL>
*> Tectonics: *> cobc -xj append.cob *> cobc -xjd -DDEBUG append.cob *> *************************************************************** identification division. program-id. append.
environment division. configuration section. repository. function all intrinsic.
input-output section. file-control. select pass-file assign to pass-filename organization is line sequential status is pass-status.
REPLACE ==:LRECL:== BY ==2048==.
data division. file section. fd pass-file record varying depending on pass-length. 01 fd-pass-record. 05 filler pic x occurs 0 to :LRECL: times depending on pass-length.
working-storage section. 01 pass-filename. 05 filler value "passfile". 01 pass-status pic xx. 88 ok-status values '00' thru '09'. 88 eof-pass value '10'.
01 pass-length usage index. 01 total-length usage index.
77 file-action pic x(11).
01 pass-record. 05 account pic x(64). 88 key-account value "xyz". 05 password pic x(64). 05 uid pic z(4)9. 05 gid pic z(4)9. 05 details. 10 fullname pic x(128). 10 office pic x(128). 10 extension pic x(32). 10 homephone pic x(32). 10 email pic x(256). 05 homedir pic x(256). 05 shell pic x(256).
77 colon pic x value ":". 77 comma-mark pic x value ",". 77 newline pic x value x"0a".
*> *************************************************************** procedure division. main-routine. perform initial-fill
>>IF DEBUG IS DEFINED display "Initial data:" perform show-records >>END-IF
perform append-record >>IF DEBUG IS DEFINED display newline "After append:" perform show-records >>END-IF
perform verify-append goback .
*> *************************************************************** initial-fill. perform open-output-pass-file
move "jsmith" to account move "x" to password move 1001 to uid move 1000 to gid move "Joe Smith" to fullname move "Room 1007" to office move "(234)555-8917" to extension move "(234)555-0077" to homephone move "jsmith@rosettacode.org" to email move "/home/jsmith" to homedir move "/bin/bash" to shell perform write-pass-record
move "jdoe" to account move "x" to password move 1002 to uid move 1000 to gid move "Jane Doe" to fullname move "Room 1004" to office move "(234)555-8914" to extension move "(234)555-0044" to homephone move "jdoe@rosettacode.org" to email move "/home/jdoe" to homedir move "/bin/bash" to shell perform write-pass-record
perform close-pass-file .
*> ********************** check-pass-file. if not ok-status then perform file-error end-if .
*> ********************** check-pass-with-eof. if not ok-status and not eof-pass then perform file-error end-if .
*> ********************** file-error. display "error " file-action space pass-filename space pass-status upon syserr move 1 to return-code goback .
*> ********************** append-record. move "xyz" to account move "x" to password move 1003 to uid move 1000 to gid move "X Yz" to fullname move "Room 1003" to office move "(234)555-8913" to extension move "(234)555-0033" to homephone move "xyz@rosettacode.org" to email move "/home/xyz" to homedir move "/bin/bash" to shell
perform open-extend-pass-file perform write-pass-record perform close-pass-file .
*> ********************** open-output-pass-file. open output pass-file with lock move "open output" to file-action perform check-pass-file .
*> ********************** open-extend-pass-file. open extend pass-file with lock move "open extend" to file-action perform check-pass-file .
*> ********************** open-input-pass-file. open input pass-file move "open input" to file-action perform check-pass-file .
*> ********************** close-pass-file. close pass-file move "closing" to file-action perform check-pass-file .
*> ********************** write-pass-record. set total-length to 1 set pass-length to :LRECL: string account delimited by space colon password delimited by space colon trim(uid leading) delimited by size colon trim(gid leading) delimited by size colon trim(fullname trailing) delimited by size comma-mark trim(office trailing) delimited by size comma-mark trim(extension trailing) delimited by size comma-mark trim(homephone trailing) delimited by size comma-mark email delimited by space colon trim(homedir trailing) delimited by size colon trim(shell trailing) delimited by size into fd-pass-record with pointer total-length on overflow display "error: fd-pass-record truncated at " total-length upon syserr end-string set pass-length to total-length set pass-length down by 1
write fd-pass-record move "writing" to file-action perform check-pass-file .
*> ********************** read-pass-file. read pass-file move "reading" to file-action perform check-pass-with-eof .
*> ********************** show-records. perform open-input-pass-file
perform read-pass-file perform until eof-pass perform show-pass-record perform read-pass-file end-perform
perform close-pass-file .
*> ********************** show-pass-record. display fd-pass-record .
*> ********************** verify-append. perform open-input-pass-file
move 0 to tally perform read-pass-file perform until eof-pass add 1 to tally unstring fd-pass-record delimited by colon into account if key-account then exit perform end-if perform read-pass-file end-perform if (key-account and tally not > 2) or (not key-account) then display "error: appended record not found in correct position" upon syserr else display "Appended record: " with no advancing perform show-pass-record end-if
perform close-pass-file .
end program append.</lang>
- Output:
prompt$ cobc -xj append.cob Appended record: xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Common Lisp
Tested on CLISP 2.49 <lang lisp>(defvar *initial_data*
(list (list "jsmith" "x" 1001 1000 (list "Joe Smith" "Room 1007" "(234)555-8917" "(234)555-0077" "jsmith@rosettacode.org") "/home/jsmith" "/bin/bash") (list "jdoe" "x" 1002 1000 (list "Jane Doe" "Room 1004" "(234)555-8914" "(234)555-0044" "jdoe@rosettacode.org") "/home/jdoe" "/bin/bash")))
(defvar *insert*
(list "xyz" "x" 1003 1000 (list "X Yz" "Room 1003" "(234)555-8913" "(234)555-0033" "xyz@rosettacode.org") "/home/xyz" "/bin/bash"))
(defun serialize (record delim)
(string-right-trim delim ;; Remove trailing delimiter (reduce (lambda (a b) (typecase b (list (concatenate 'string a (serialize b ",") delim)) (t (concatenate 'string a (typecase b (integer (write-to-string b)) (t b)) delim)))) record :initial-value "")))
(defun main ()
;; Write initial values to file (with-open-file (stream "./passwd" :direction :output :if-exists :supersede :if-does-not-exist :create) (loop for x in *initial_data* do (format stream (concatenate 'string (serialize x ":") "~%"))))
;; Reopen file, append insert value (with-open-file (stream "./passwd" :direction :output :if-exists :append) (format stream (concatenate 'string (serialize *insert* ":") "~%")))
;; Reopen file, search for new record (with-open-file (stream "./passwd") (when stream (loop for line = (read-line stream nil) while line do (if (search "xyz" line) (format t "Appended record: ~a~%" line))))))
(main) </lang>
- Output:
$ clisp append_file.cl Appended record: xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
Lists | Text file | Common Lisp Standard Library | ☑ | ☑ | ☑ (Hopefully!) |
D
<lang D>class Record {
private const string account; private const string password; private const int uid; private const int gid; private const string[] gecos; private const string directory; private const string shell;
public this(string account, string password, int uid, int gid, string[] gecos, string directory, string shell) { import std.exception; this.account = enforce(account); this.password = enforce(password); this.uid = uid; this.gid = gid; this.gecos = enforce(gecos); this.directory = enforce(directory); this.shell = enforce(shell); }
public void toString(scope void delegate(const(char)[]) sink) const { import std.conv : toTextRange; import std.format : formattedWrite; import std.range : put;
sink(account); put(sink, ':'); sink(password); put(sink, ':'); toTextRange(uid, sink); put(sink, ':'); toTextRange(gid, sink); put(sink, ':'); formattedWrite(sink, "%-(%s,%)", gecos); put(sink, ':'); sink(directory); put(sink, ':'); sink(shell); }
}
public Record parse(string text) {
import std.array : split; import std.conv : to; import std.string : chomp;
string[] tokens = text.chomp.split(':'); return new Record( tokens[0], tokens[1], to!int(tokens[2]), to!int(tokens[3]), tokens[4].split(','), tokens[5], tokens[6]);
}
void main() {
import std.algorithm : map; import std.file : exists, mkdir; import std.stdio;
auto rawData = [ "jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash", "jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash", "xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash" ];
auto records = rawData.map!parse;
if (!exists("_rosetta")) { mkdir("_rosetta"); }
auto passwd = File("_rosetta/.passwd", "w"); passwd.lock(); passwd.writeln(records[0]); passwd.writeln(records[1]); passwd.unlock(); passwd.close();
passwd.open("_rosetta/.passwd", "a"); passwd.lock(); passwd.writeln(records[2]); passwd.unlock(); passwd.close();
passwd.open("_rosetta/.passwd"); foreach(string line; passwd.lines()) { parse(line).writeln(); } passwd.close();
}</lang>
- Output:
jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Elixir
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
objects (subclass of Struct builtin) | text file | builtin | ☑ | ☑ | ☒ |
<lang elixir> defmodule Gecos do
defstruct [:fullname, :office, :extension, :homephone, :email] defimpl String.Chars do def to_string(gecos) do [:fullname, :office, :extension, :homephone, :email] |> Enum.map_join(",", &Map.get(gecos, &1)) end end
end
defmodule Passwd do
defstruct [:account, :password, :uid, :gid, :gecos, :directory, :shell] defimpl String.Chars do def to_string(passwd) do [:account, :password, :uid, :gid, :gecos, :directory, :shell] |> Enum.map_join(":", &Map.get(passwd, &1)) end end
end
defmodule Appender do
def write(filename) do jsmith = %Passwd{ account: "jsmith", password: "x", uid: 1001, gid: 1000, gecos: %Gecos{ fullname: "Joe Smith", office: "Room 1007", extension: "(234)555-8917", homephone: "(234)555-0077", email: "jsmith@rosettacode.org" }, directory: "/home/jsmith", shell: "/bin/bash" } jdoe = %Passwd{ account: "jdoe", password: "x", uid: 1002, gid: 1000, gecos: %Gecos{ fullname: "Jane Doe", office: "Room 1004", extension: "(234)555-8914", homephone: "(234)555-0044", email: "jdoe@rosettacode.org" }, directory: "/home/jdoe", shell: "/bin/bash" } xyz = %Passwd{ account: "xyz", password: "x", uid: 1003, gid: 1000, gecos: %Gecos{ fullname: "X Yz", office: "Room 1003", extension: "(234)555-8913", homephone: "(234)555-0033", email: "xyz@rosettacode.org" }, directory: "/home/xyz", shell: "/bin/bash" } File.open!(filename, [:write], fn file -> IO.puts(file, jsmith) IO.puts(file, jdoe) end) File.open!(filename, [:append], fn file -> IO.puts(file, xyz) end) IO.puts File.read!(filename) end
end
Appender.write("passwd.txt") </lang>
- Output:
jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Fortran
Prior to F90, data aggregates can't be defined so one would use an assemblage of variables (perhaps with similar names) and be diligent over every READ and WRITE statement naming them all and in the right order. With F90 the assemblage can be declared via a single name such as NOTE which has subcomponents, if defined via repeated use of TYPE. In COBOL and pl/i, the definition of an aggregate can be done more smoothly. A further difficulty is that character variables have a fixed size, and there is no length field to allow a "string" style usage. Fortran 2003 formalised a scheme whereby character variables can be re-allocated with a suitable size on assignment so that for example NOTE.ACCOUNT = "Fred"
would regenerate the variable as a four-character text until it was next assigned to, and there would be no trailing spaces as there are when the variable's length is fixed at 28. However, when written, there is no indication of the actual length of such a variable.
In the absence of a length indication, when outputting text variables with a view to having them read in again, delimiting them with quotes (and doubling internal quotes) is the route to peace of mind, because otherwise a text might contain a comma as in "43 Gurney Road, Belmont" and in the absence of quoting, such a sequence on input might well be taken as two fields rather than one and a mess is certain. This facility is offered by the free-format (or, "list directed") style initiated by the use of * in place of a format label, as in WRITE (MSG,*) etc.
, provided however that the output file has been opened with the optional usage attribute DELIM = "QUOTE"
, an unfortunate choice of name, because the field separator character could also be termed a "delimiter" and the default value is both a space or comma, when often what is preferable is only a comma, or even a tab. But there is no standard method to specify this desire. Only if the texts never themselves contain commas or spaces will this unquoted free-format scheme evade extra effort, and the specified example precludes this simplicity.
The resulting output is strung along an output line, with a default line length of 132 (a standard lineprinter width); the specification of RECL = 666 ensures that all the output fields are rolled to one line - that isn't padded out to 666 characters: this is not a fixed-length record despite the specification of RECL as a constant, though each record turns out to be 248 characters long. Unfortunately, the trailing spaces in each character variable are rolled forth and there is no option along the lines of WRITE (MSG,*) TRIM(NOTE)
One could instead use a suitable FORMAT statement with "A" format codes, but every element of NOTE would have to be named in the output list and the TRIM function applied only to each character field. Not only would this be tedious and error-prone, there is no format code for the enquoting and double-quoting of the texts and thus, no peace of mind... One would of course devise a subroutine to write out such a record (which would probably be more complex, with the FULLNAME subdivided, etc.), but the task's main objective is to demonstrate appending output to a file.<lang Fortran> PROGRAM DEMO !As per the described task, more or less.
TYPE DETAILS !Define a component. CHARACTER*28 FULLNAME CHARACTER*12 OFFICE CHARACTER*16 EXTENSION CHARACTER*16 HOMEPHONE CHARACTER*88 EMAIL END TYPE DETAILS TYPE USERSTUFF !Define the desired data aggregate. CHARACTER*8 ACCOUNT CHARACTER*8 PASSWORD !Plain text!! Eeek!!! INTEGER*2 UID INTEGER*2 GID TYPE(DETAILS) PERSON CHARACTER*18 DIRECTORY CHARACTER*12 SHELL END TYPE USERSTUFF TYPE(USERSTUFF) NOTE !After all that, I'll have one. NAMELIST /STUFF/ NOTE !Enables free-format I/O, with names. INTEGER F,MSG,N MSG = 6 !Standard output. F = 10 !Suitable for some arbitrary file. OPEN(MSG, DELIM = "QUOTE") !Text variables are to be enquoted.
Create the file and supply its initial content.
OPEN (F, FILE="Staff.txt",STATUS="REPLACE",ACTION="WRITE", 1 DELIM="QUOTE",RECL=666) !Special parameters for the free-format WRITE working.
WRITE (F,*) USERSTUFF("jsmith","x",1001,1000, 1 DETAILS("Joe Smith","Room 1007","(234)555-8917", 2 "(234)555-0077","jsmith@rosettacode.org"), 2 "/home/jsmith","/bin/bash")
WRITE (F,*) USERSTUFF("jdoe","x",1002,1000, 1 DETAILS("Jane Doe","Room 1004","(234)555-8914", 2 "(234)555-0044","jdoe@rosettacode.org"), 3 "home/jdoe","/bin/bash") CLOSE (F) !The file is now existing.
Choose the existing file, and append a further record to it.
OPEN (F, FILE="Staff.txt",STATUS="OLD",ACTION="WRITE", 1 DELIM="QUOTE",RECL=666,ACCESS="APPEND")
NOTE = USERSTUFF("xyz","x",1003,1000, !Create a new record's worth of stuff. 1 DETAILS("X Yz","Room 1003","(234)555-8193", 2 "(234)555-033","xyz@rosettacode.org"), 3 "/home/xyz","/bin/bash") WRITE (F,*) NOTE !Append its content to the file. CLOSE (F)
Chase through the file, revealing what had been written..
OPEN (F, FILE="Staff.txt",STATUS="OLD",ACTION="READ", 1 DELIM="QUOTE",RECL=666) N = 0 10 READ (F,*,END = 20) NOTE !As it went out, so it comes in. N = N + 1 !Another record read. WRITE (MSG,11) N !Announce. 11 FORMAT (/,"Record ",I0) !Thus without quotes around the text part. WRITE (MSG,STUFF) !Reveal. GO TO 10 !Try again.
Closedown.
20 CLOSE (F) END</lang>
The output can be read back in with the same free-format style. The fields are separated by spaces (outside a quoted string) though commas are also allowed. The file content is as follows:
"jsmith " "x " 1001 1000 "Joe Smith " "Room 1007 " "(234)555-8917 " "(234)555-0077 " "jsmith@rosettacode.org " "/home/jsmith " "/bin/bash " "jdoe " "x " 1002 1000 "Jane Doe " "Room 1004 " "(234)555-8914 " "(234)555-0044 " "jdoe@rosettacode.org " "home/jdoe " "/bin/bash " "xyz " "x " 1003 1000 "X Yz " "Room 1003 " "(234)555-8193 " "(234)555-033 " "xyz@rosettacode.org " "/home/xyz " "/bin/bash "
Numerical values are written with sufficient space to allow for their maximum value, so the sixteen-bit integers are allowed six spaces (in case a minus sign might be needed) and so on for other types. Thus, complex numbers are written in the (real,imaginary) style. Given this fixed layout, an explicit FORMAT statement could be used and delimiters be abandoned along with worry over quoting, but any changes to the data structure will require corresponding changes to the associated FORMAT statement, and mistakes are easily made. For input via free-format, the trailing spaces in the quoted strings could be omitted; any needed will be supplied by the READ process.
To demonstrate that they have been read successfully, the data aggregate is printed out using the NAMELIST protocol, whereby each item in the output list is presented in the form <name> = <value>, as follows:
Record 1 &STUFF NOTE%ACCOUNT = "jsmith ", NOTE%PASSWORD = "x ", NOTE%UID = 1001, NOTE%GID = 1000, NOTE%PERSON%FULLNAME = "Joe Smith ", NOTE%PERSON%OFFICE = "Room 1007 ", NOTE%PERSON%EXTENSION = "(234)555-8917 ", NOTE%PERSON%HOMEPHONE = "(234)555-0077 ", NOTE%PERSON%EMAIL = "jsmith@rosettacode.org ", NOTE%DIRECTORY = "/home/jsmith ", NOTE%SHELL = "/bin/bash " / Record 2 &STUFF NOTE%ACCOUNT = "jdoe ", NOTE%PASSWORD = "x ", NOTE%UID = 1002, NOTE%GID = 1000, NOTE%PERSON%FULLNAME = "Jane Doe ", NOTE%PERSON%OFFICE = "Room 1004 ", NOTE%PERSON%EXTENSION = "(234)555-8914 ", NOTE%PERSON%HOMEPHONE = "(234)555-0044 ", NOTE%PERSON%EMAIL = "jdoe@rosettacode.org ", NOTE%DIRECTORY = "home/jdoe ", NOTE%SHELL = "/bin/bash " / Record 3 &STUFF NOTE%ACCOUNT = "xyz ", NOTE%PASSWORD = "x ", NOTE%UID = 1003, NOTE%GID = 1000, NOTE%PERSON%FULLNAME = "X Yz ", NOTE%PERSON%OFFICE = "Room 1003 ", NOTE%PERSON%EXTENSION = "(234)555-8193 ", NOTE%PERSON%HOMEPHONE = "(234)555-033 ", NOTE%PERSON%EMAIL = "xyz@rosettacode.org ", NOTE%DIRECTORY = "/home/xyz ", NOTE%SHELL = "/bin/bash " /
Because the output file (MSG) was opened with DELIM="QUOTE", the text variables are presented enquoted. This makes it clear whether fields have leading spaces or not, which with the usual proportionally-spaced typefaces and .html rendering is not clear in the example and could cause serious difficulty in practice as between "Joe Bloggs" and " Joe Bloggs". Because the DELIM feature applies to both free-format and namelist output, WRITE (MSG,*) "Record",N
would produce output with the text "Record" in quotes, so instead a suitable FORMAT statement is used. Alas, for compound names the % symbol is used instead of a period, a pity. NAMELIST style I/O starts with "&STUFF" (the name of the NAMELIST) and ends with "/" and like free-format output, starts each line with a space that would be consumed as a carriage-control character for lineprinter output.
The "append" to a file is available only if the ACCESS="APPEND" facility is available, and alas, this is not standard Fortran though a common extension. Files opened for output are exclusive use. If a file exists but is in use, the OPEN statement will fail, so one should include the ERR=label,IOSTAT=WHAT
to attempt to recover from lockouts. Except that IOSTAT error codes for a given problem may well vary from one system to another.
FreeBASIC
<lang freebasic>' FB 1.05.0 Win64
Type Person
As String fullname As String office As String extension As String homephone As String email Declare Constructor() Declare Constructor(As String, As String, As String, As String, As String) Declare Operator Cast() As String
End Type
Constructor Person() End Constructor
Constructor Person(fullname As String, office As String, extension As String, _ homephone As String, email As String)
With This .fullname = fullname .office = office .extension = extension .homephone = homephone .email = email End With
End Constructor
Operator Person.Cast() As String
Return fullname + "," + office + "," + extension + "," + homephone + "," + email
End Operator
Type Record
As String account As String password As Integer uid As Integer gid As Person user As String directory As String shell Declare Constructor() Declare Constructor(As String, As String, As Integer, As Integer, As Person, As String, As String) Declare Operator Cast() As String
End Type
Constructor Record() End Constructor
Constructor Record(account As String, password As String, uid As Integer, gid As Integer, user As Person, _ directory As String, shell As String)
With This .account = account .password = password .uid = uid .gid = gid .user = user .directory = directory .shell = shell End With
End Constructor
Operator Record.Cast() As String
Return account + ":" + password + ":" + Str(uid) + ":" + Str(gid) + ":" + user + ":" + directory + ":" + shell
End Operator
Dim persons(1 To 3) As Person persons(1) = Person("Joe Smith", "Room 1007", "(234)555-8917", "(234)555-0077", "jsmith@rosettacode.org") persons(2) = Person("Jane Doe", "Room 1004", "(234)555-8914", "(234)555-0044", "jdoe@rosettacode.org" ) persons(3) = Person("X Yz", "Room 1003", "(234)555-8913", "(234)555-0033", "xyz@rosettacode.org" )
Dim records(1 To 3) As Record records(1) = Record("jsmith", "x", 1001, 1000, persons(1), "/home/jsmith", "/bin/bash") records(2) = Record("jdoe", "x", 1002, 1000, persons(2), "/home/jdoe" , "/bin/bash") records(3) = Record("xyz", "x", 1003, 1000, persons(3), "/home/xyz" , "/bin/bash")
Open "passwd.txt" For Output As #1 Print #1, records(1) Print #1, records(2) Close #1
Open "passwd.txt" For Append Lock Write As #1 Print #1, records(3) Close #1</lang>
- Output:
' contents of passwd.txt after appending the third record jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
FB Type | CSV text file | FB Standard Library | ☑ | ☑ | ☑ (Hopefully!) |
Go
<lang go>package main
import (
"bytes" "fmt" "io" "io/ioutil" "os"
)
type pw struct {
account, password string uid, gid uint gecos directory, shell string
}
type gecos struct {
fullname, office, extension, homephone, email string
}
func (p *pw) encode(w io.Writer) (int, error) {
return fmt.Fprintf(w, "%s:%s:%d:%d:%s,%s,%s,%s,%s:%s:%s\n", p.account, p.password, p.uid, p.gid, p.fullname, p.office, p.extension, p.homephone, p.email, p.directory, p.shell)
}
// data cut and pasted from task description var p2 = []pw{
{"jsmith", "x", 1001, 1000, gecos{"Joe Smith", "Room 1007", "(234)555-8917", "(234)555-0077", "jsmith@rosettacode.org"}, "/home/jsmith", "/bin/bash"}, {"jdoe", "x", 1002, 1000, gecos{"Jane Doe", "Room 1004", "(234)555-8914", "(234)555-0044", "jdoe@rosettacode.org"}, "/home/jsmith", "/bin/bash"},
}
var pa = pw{"xyz", "x", 1003, 1000, gecos{"X Yz", "Room 1003",
"(234)555-8913", "(234)555-0033", "xyz@rosettacode.org"}, "/home/xyz", "/bin/bash"}
var expected = "xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913," +
"(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash"
const pfn = "mythical"
func main() {
writeTwo() appendOneMore() checkResult()
}
func writeTwo() {
// overwrites any existing file f, err := os.Create(pfn) if err != nil { fmt.Println(err) return } defer func() { if cErr := f.Close(); cErr != nil && err == nil { fmt.Println(cErr) } }() for _, p := range p2 { if _, err = p.encode(f); err != nil { fmt.Println(err) return } }
}
func appendOneMore() {
// file must already exist f, err := os.OpenFile(pfn, os.O_RDWR|os.O_APPEND, 0) if err != nil { fmt.Println(err) return } if _, err := pa.encode(f); err != nil { fmt.Println(err) } if cErr := f.Close(); cErr != nil && err == nil { fmt.Println(cErr) }
}
func checkResult() {
// reads entire file then closes it b, err := ioutil.ReadFile(pfn) if err != nil { fmt.Println(err) return } if string(bytes.Split(b, []byte{'\n'})[2]) == expected { fmt.Println("append okay") } else { fmt.Println("it didn't work") }
}</lang>
- Output:
append okay
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
Byte slice. See note 1. | Abstracted. See note 2. | Go standard library. See note 3. | Yes | No. See note 4. | Should be, but see note 5. |
Notes:
- Data arguments for basic IO functions are type []byte. All data being written ultimately gets encoded to []byte. Some higher level functions accept strings and do the conversion as a convenience. The fmt.Fprintf function used in this task encodes basic types directly to an io.Writer. Some packages such as json and xml have marshallers to encode more complex data structures. These features are common to all writes and are not specific to append.
- The device data representation is abstracted by the type os.File and its associated functions and methods. These methods include seeking by linear file position so a typical data representation is mappable to a linear sequence of bytes. That is about all that can be concluded from the capabilites of the os.File type. This linear nature is not specific to append.
- Go's os package provides high-level services which work reasonably the same across all supported operating systems. Currently the list is darwin, freebsd, linux, netbsd, openbsd, windows. It does this with a common OS-independent interface. Operations which cannot be offered accross all operating systems are not in this package. Additional low-level and operating system specific functions are provided in the syscall package. This organization is not specific to append.
- The file position after opening a file is 0 unless os.O_APPEND is specified in the os.OpenFile function.
- The Go documentation says nothing about file operations by multiple concurrent processes or threads. As the operations are expected to work the same across operating systems however, they presumably do what you would expect. It seems os.FileOpen with os.O_RDWR for example, gives exclusive file access (on local file systems anyway) whether os.O_APPEND is specified or not.
Groovy
Solution: <lang groovy>class PasswdRecord {
String account, password, directory, shell int uid, gid SourceRecord source
private static final fs = ':' private static final fieldNames = ['account', 'password', 'uid', 'gid', 'source', 'directory', 'shell'] private static final stringFields = ['account', 'password', 'directory', 'shell'] private static final intFields = ['uid', 'gid']
PasswdRecord(String line = null) { if (!line) return def fields = line.split(fs) if (fields.size() != fieldNames.size()) { throw new IllegalArgumentException( "Passwd record must have exactly ${fieldNames.size()} '${fs}'-delimited fields") } (0..<fields.size()).each { i -> switch (fieldNames[i]) { case stringFields: this[fieldNames[i]] = fields[i]; break case intFields: this[fieldNames[i]] = fields[i] as Integer; break default /* source */: this.source = new SourceRecord(fields[i]); break } } }
@Override String toString() { fieldNames.collect { "${this[it]}${fs}" }.sum()[0..-2] }
}
class SourceRecord {
String fullname, office, extension, homephone, email
private static final fs = ',' private static final fieldNames = ['fullname', 'office', 'extension', 'homephone', 'email']
SourceRecord(String line = null) { if (!line) return def fields = line.split(fs) if (fields.size() != fieldNames.size()) { throw new IllegalArgumentException( "Source record must have exactly ${fieldNames.size()} '${fs}'-delimited fields") } (0..<fields.size()).each { i -> this[fieldNames[i]] = fields[i] } }
@Override String toString() { fieldNames.collect { "${this[it]}${fs}" }.sum()[0..-2] }
}
def appendNewPasswdRecord = {
PasswdRecord pwr = new PasswdRecord().with { p -> (account, password, uid, gid) = ['xyz', 'x', 1003, 1000] source = new SourceRecord().with { s -> (fullname, office, extension, homephone, email) = ['X Yz', 'Room 1003', '(234)555-8913', '(234)555-0033', 'xyz@rosettacode.org'] s } (directory, shell) = ['/home/xyz', '/bin/bash'] p };
new File('passwd.txt').withWriterAppend { w -> w.append(pwr as String) w.append('\r\n') }
}</lang>
Test: <lang groovy>def checkPasswdFile = { it ->
File passwd = new File('passwd.txt') assert passwd.exists()
passwd.eachLine { line -> def pw = new PasswdRecord(line) assert pw && pw instanceof PasswdRecord assert pw.source && pw.source instanceof SourceRecord println pw }
println()
}
println "File contents before new record added" checkPasswdFile()
appendNewPasswdRecord()
println "File contents after new record added" checkPasswdFile()</lang>
Output:
File contents before new record added jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jsmith:/bin/bash File contents after new record added jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jsmith:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Haskell
Solution: <lang haskell> {-# LANGUAGE RecordWildCards #-}
import System.IO import Data.List (intercalate)
data Gecos = Gecos { fullname :: String
, office :: String , extension :: String , homephone :: String , email :: String }
data Record = Record { account :: String
, password :: String , uid :: Int , gid :: Int , directory :: String , shell :: String , gecos :: Gecos }
instance Show Gecos where
show (Gecos {..}) = intercalate "," [fullname, office, extension, homephone, email]
instance Show Record where
show (Record {..}) = intercalate ":" [account, password, show uid, show gid, show gecos, directory, shell]
addRecord :: String -> Record -> IO () addRecord path r = appendFile path (show r) </lang>
Test: <lang haskell> t1 = Record "jsmith" "x" 1001 1000 "/home/jsmith" "/bin/bash"
(Gecos "Joe Smith" "Room 1007" "(234)555-8917" "(234)555-0077" "jsmith@rosettacode.org")
t2 = Record "jdoe" "x" 1002 1000 "/home/jdoe" "/bin/bash"
(Gecos "Jane Doe" "Room 1004" "(234)555-8914" "(234)555-0044" "jdoe@rosettacode.org")
t3 = Record "xyz" "x" 1003 1000 "/home/xyz" "/bin/bash"
(Gecos "X Yz" "Room 1003" "(234)555-8913" "(234)555-0033" "xyz@rosettacode.org")
main = do
let path = "test.txt" forM [t1,t2,t3] (addRecord path) lastLine <- fmap (last . lines) (readFile path) putStrLn lastLine
</lang>
Icon and Unicon
Works in both languages: <lang unicon>procedure main()
orig := [ "jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash", "jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jsmith:/bin/bash" ] new := [ "xyz:x:1003:1000:X:Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash" ] fName := !open("mktemp","rp") every (f := open(fName,"w")) | write(f,!orig) | close(f) every (f := open(fName,"a")) | write(f,!new) | close(f) every (f := open(fName,"r")) | write(!f) | close(f)
end</lang>
Run:
->arteotf jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jsmith:/bin/bash xyz:x:1003:1000:X:Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash ->
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
String | String | built-in | ☑ | ☑ | ☑ (Not all, eg NFS) |
J
<lang j>require'strings ~system/packages/misc/xenos.ijs' record=: [:|: <@deb;._1@(':',]);._2@do bind '0 :0'
passfields=: <;._1':username:password:gid:uid:gecos:home:shell'
passrec=: LF,~ [: }.@;@ , ':';"0 (passfields i. {. ) { a:,~ {:
R1=: passrec record
username: jsmith password: x gid: 1001 uid: 1000 gecos: Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org home: /home/jsmith shell: /bin/bash
)
R2=: passrec record
username: jdoe password: x gid: 1002 uid: 1000 gecos: Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org home: /home/jdoe shell: /bin/bash
)
R3=: passrec record
username: xyz password: x gid: 1003 uid: 1000 gecos: X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org home: /home/xyz shell: /bin/bash
)
passwd=: <'/tmp/passwd.txt' NB. file needs to be writable on implementation machine
(R1,R2) fwrite passwd R3 fappend passwd
assert 1 e. R3 E. fread passwd </lang>
Data Representation | |
---|---|
In core | On disk |
array | literal |
Note that no file locking is needed if this is implemented under windows (since all file writes are atomic across processes -- only one process can have a file open at one time, by default). Note that file locking would be needed under Linux (or unix), but it's not clear which file locking mechanism should be used.
Java
<lang java>import static java.util.Objects.requireNonNull;
import java.io.IOException; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.nio.file.StandardOpenOption; import java.util.Arrays; import java.util.Collections; import java.util.List; import java.util.stream.Collectors; import java.util.stream.Stream;
public class RecordAppender {
static class Record { private final String account; private final String password; private final int uid; private final int gid; private final List<String> gecos; private final String directory; private final String shell;
public Record(String account, String password, int uid, int gid, List<String> gecos, String directory, String shell) { this.account = requireNonNull(account); this.password = requireNonNull(password); this.uid = uid; this.gid = gid; this.gecos = requireNonNull(gecos); this.directory = requireNonNull(directory); this.shell = requireNonNull(shell); }
@Override public String toString() { return account + ':' + password + ':' + uid + ':' + gid + ':' + String.join(",", gecos) + ':' + directory + ':' + shell; }
public static Record parse(String text) { String[] tokens = text.split(":"); return new Record( tokens[0], tokens[1], Integer.parseInt(tokens[2]), Integer.parseInt(tokens[3]), Arrays.asList(tokens[4].split(",")), tokens[5], tokens[6]); } }
public static void main(String[] args) throws IOException { List<String> rawData = Arrays.asList( "jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,[email protected]:/home/jsmith:/bin/bash", "jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,[email protected]:/home/jdoe:/bin/bash", "xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,[email protected]:/home/xyz:/bin/bash" );
List<Record> records = rawData.stream().map(Record::parse).collect(Collectors.toList());
Path tmp = Paths.get("_rosetta", ".passwd"); Files.createDirectories(tmp.getParent()); Files.write(tmp, (Iterable<String>) records.stream().limit(2).map(Record::toString)::iterator);
Files.write(tmp, Collections.singletonList(records.get(2).toString()), StandardOpenOption.APPEND);
try (Stream<String> lines = Files.lines(tmp)) { lines.map(Record::parse).forEach(System.out::println); } }
}</lang>
- Output:
Appended Record: xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Julia
<lang julia> using SHA # security instincts say do not write bare passwords to a shared file even in toy code :)
mutable struct Personnel
fullname::String office::String extension::String homephone::String email::String Personnel(ful,off,ext,hom,ema) = new(ful,off,ext,hom,ema)
end
mutable struct Passwd
account::String password::String uid::Int32 gid::Int32 personal::Personnel directory::String shell::String Passwd(acc,pas,uid,gid,per,dir,she) = new(acc,pas,uid,gid,per,dir,she)
end
function writepasswd(filename, passrecords)
if(passrecords isa Array) == false passrecords = [passrecords] end fh = open(filename, "a") # should throw an exception if cannot open in a locked or exclusive mode for append for pas in passrecords record = join([pas.account, bytes2hex(sha256(pas.password)), pas.uid, pas.gid, join([pas.personal.fullname, pas.personal.office, pas.personal.extension, pas.personal.homephone, pas.personal.email], ','), pas.directory, pas.shell], ':') write(fh, record, "\n") end close(fh)
end
const jsmith = Passwd("jsmith","x",1001, 1000, Personnel("Joe Smith", "Room 1007", "(234)555-8917", "(234)555-0077", "jsmith@rosettacode.org"), "/home/jsmith", "/bin/bash") const jdoe = Passwd("jdoe","x",1002, 1000, Personnel("Jane Doe", "Room 1004", "(234)555-8914", "(234)555-0044", "jdoe@rosettacode.org"), "/home/jdoe", "/bin/bash") const xyz = Passwd("xyz","x",1003, 1000, Personnel("X Yz", "Room 1003", "(234)555-8913", "(234)555-0033", "xyz@rosettacode.org"), "/home/xyz", "/bin/bash")
const pfile = "pfile.csv" writepasswd(pfile, [jsmith, jdoe]) println("Before last record added, file is:\n$(readstring(pfile))") writepasswd(pfile, xyz) println("After last record added, file is:\n$(readstring(pfile))") </lang>
- Output:
Before last record added, file is: jsmith:2d711642b726b04401627ca9fbac32f5c8530fb1903cc4db02258717921a4881:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:2d711642b726b04401627ca9fbac32f5c8530fb1903cc4db02258717921a4881:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash
After last record added, file is: jsmith:2d711642b726b04401627ca9fbac32f5c8530fb1903cc4db02258717921a4881:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:2d711642b726b04401627ca9fbac32f5c8530fb1903cc4db02258717921a4881:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:2d711642b726b04401627ca9fbac32f5c8530fb1903cc4db02258717921a4881:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Kotlin
<lang scala>// Version 1.2.41
import java.io.File
class Record(
val account: String, val password: String, val uid: Int, val gid: Int, val gecos: List<String>, val directory: String, val shell: String
){
override fun toString() = "$account:$password:$uid:$gid:${gecos.joinToString(",")}:$directory:$shell"
}
fun parseRecord(line: String): Record {
val fields = line.split(':') return Record( fields[0], fields[1], fields[2].toInt(), fields[3].toInt(), fields[4].split(','), fields[5], fields[6] )
}
fun main(args: Array<String>) {
val startData = listOf( "jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,[email protected]:/home/jsmith:/bin/bash", "jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,[email protected]:/home/jdoe:/bin/bash" ) val records = startData.map { parseRecord(it) } val f = File("passwd.csv") f.printWriter().use { for (record in records) it.println(record) } println("Initial records:\n") f.forEachLine { println(parseRecord(it)) }
val newData = "xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,[email protected]:/home/xyz:/bin/bash" val record = parseRecord(newData) if (!f.setWritable(true, true)) { println("\nFailed to make file writable only by owner\n.") } f.appendText("$record\n") println("\nRecords after another one is appended:\n") f.forEachLine { println(parseRecord(it)) }
}</lang>
- Output:
Initial records: jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,[email protected]:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,[email protected]:/home/jdoe:/bin/bash Records after another one is appended: jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,[email protected]:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,[email protected]:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,[email protected]:/home/xyz:/bin/bash
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
Class | Text file | JDK | ☑ | ☑ | ☑ (System dependent) |
Lua
<lang lua>function append(tbl,filename)
local file,err = io.open(filename, "a") if err then return err end
file:write(tbl.account..":") file:write(tbl.password..":") file:write(tbl.uid..":") file:write(tbl.gid..":")
for i,v in ipairs(tbl.gecos) do if i>1 then file:write(",") end file:write(v) end file:write(":")
file:write(tbl.directory..":") file:write(tbl.shell.."\n")
file:close()
end
local smith = {} smith.account = "jsmith" smith.password = "x" smith.uid = 1001 smith.gid = 1000 smith.gecos = {"Joe Smith", "Room 1007", "(234)555-8917", "(234)555-0077", "jsmith@rosettacode.org"} smith.directory = "/home/jsmith" smith.shell = "/bin/bash" append(smith, ".passwd")
local doe = {} doe.account = "jdoe" doe.password = "x" doe.uid = 1002 doe.gid = 1000 doe.gecos = {"Jane Doe", "Room 1004", "(234)555-8914", "(234)555-0044", "jdoe@rosettacode.org"} doe.directory = "/home/jdoe" doe.shell = "/bin/bash" append(doe, ".passwd")
local xyz = {} xyz.account = "xyz" xyz.password = "x" xyz.uid = 1003 xyz.gid = 1000 xyz.gecos = {"X Yz", "Room 1003", "(234)555-8913", "(234)555-0033", "xyz@rosettacode.org"} xyz.directory = "/home/xyz" xyz.shell = "/bin/bash" append(xyz, ".passwd")</lang>
M2000 Interpreter
<lang M2000 Interpreter>Module TestThis { Class passwd { account$, password$ UID, GID group GECOS { fullname$,office$,extension$,homephone$,email$ function Line$() { =format$("{0},{1} {2},{3},{4}", .fullname$,.office$,.extension$,.homephone$,.email$) } } directory$, shell$ Function Line$() { =format$("{0}:{1}:{2}:{3}:{4}:{5}:{6}",.account$,.password$, .UID, .GID, .GECOS.Line$(), .directory$, .shell$) } class: Module passwd { if match("SSNNSSSSSSS") then Read .account$, .password$ Read .UID, .GID For .GECOS { Read .fullname$,.office$,.extension$,.homephone$,.email$ } Read .directory$, .shell$ Else.If Match("S") then Dim a$(), b$() a$()=Piece$(letter$, ":") .account$<=a$(0) .password$<=a$(1) .UID<=Val(a$(2)) .GID<=Val(a$(3)) For .GECOS { b$()=Piece$(a$(4), ",") .fullname$<=b$(0) .office$<=Piece$(b$(1), " ")(0) .extension$<=Piece$(b$(1), " ")(1) .homephone$<=b$(2) .email$<=b$(3) } .directory$<=a$(5) .shell$<=a$(6) End if } } Flush Data PASSWD("jsmith", "x", 1001, 1000, "Joe Smith", "Room", "1007","(234)555-8917","(234)555-0077","jsmith@rosettacode.org","/home/jsmith","/bin/bash") Data PASSWD("jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044:jdoe@rosettacode.org:/home/jdoe") \\ we have to make the file if not exist before we use APPEND if not exist("passwd") then Open "passwd" for Output as #F Close #F end if Open "passwd" for wide append as #F While not empty read A Print #F, A.Line$() End While Close #F Ret=PASSWD("xyz","x",1003,1000,"X Yz", "Room", "1003", "(234)555-8913", "(234)555-0033", "xyz@rosettacode.org","/home/xyz","/bin/bash") Repeat Try ok { Open "passwd" for wide append exclusive as F Print #F, Ret.Line$() close #F }
Until Not (Error or Not ok) I=1 Document Ret$ Open "passwd" for wide input as #F While not Eof(#F) Line Input #F, record$ Ret$=Format$("{0}|{1}",Str$(I,"0000"),Record$)+{ } I++ End While Close #F ClipBoard Ret$ Report Ret$ } TestThis </lang>
- Output:
0001|jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077:jsmith@rosettacode.org:/home/jsmith 0002|jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044:jdoe@rosettacode.org:/home/jdoe 0003|xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033:xyz@rosettacode.org:/home/xyz
Mathematica / Wolfram Language
<lang Mathematica>data = <|"account" -> "xyz", "password" -> "x", "UID" -> 1003,
"GID" -> 1000, "fullname" -> "X Yz", "office" -> "Room 1003", "extension" -> "(234)555-8913", "homephone" -> "(234)555-0033", "email" -> "xyz@rosettacode.org", "directory" -> "/home/xyz", "shell" -> "/bin/bash"|>;
asString[data_] :=
StringRiffle[ ToString /@ Insert[data /@ {"account", "password", "UID", "GID", "directory", "shell"}, StringRiffle[ data /@ {"fullname", "office", "extension", "homephone", "email"}, ","], 5], ":"];
fname = FileNameJoin[{$TemporaryDirectory, "testfile"}]; str = OpenWrite[fname]; (* Use OpenAppend if file exists *) Close[str]; Print["Appended record: " <> asString[data]];</lang>
- Output:
Appended record: xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
Association | Nearly anything | Standard Library | ☑ | ☑ | ☐ |
MATLAB / Octave
<lang Matlab> DS{1}.account='jsmith';
DS{1}.password='x'; DS{1}.UID=1001; DS{1}.GID=1000; DS{1}.fullname='Joe Smith'; DS{1}.office='Room 1007'; DS{1}.extension='(234)555-8917'; DS{1}.homephone='(234)555-0077'; DS{1}.email='jsmith@rosettacode.org'; DS{1}.directory='/home/jsmith'; DS{1}.shell='/bin/bash';
DS{2}.account='jdoe'; DS{2}.password='x'; DS{2}.UID=1002; DS{2}.GID=1000; DS{2}.fullname='Jane Doe'; DS{2}.office='Room 1004'; DS{2}.extension='(234)555-8914'; DS{2}.homephone='(234)555-0044'; DS{2}.email='jdoe@rosettacode.org'; DS{2}.directory='/home/jdoe'; DS{2}.shell='/bin/bash';
function WriteRecord(fid, rec) fprintf(fid,"%s:%s:%i:%i:%s,%s,%s,%s,%s:%s%s\n", rec.account, rec.password, rec.UID, rec.GID, rec.fullname, rec.office, rec.extension, rec.homephone, rec.email, rec.directory, rec.shell); return; end
%% write fid = fopen('passwd.txt','w'); WriteRecord(fid,DS{1}); WriteRecord(fid,DS{2}); fclose(fid);
new.account='xyz'; new.password='x'; new.UID=1003; new.GID=1000; new.fullname='X Yz'; new.office='Room 1003'; new.extension='(234)555-8913'; new.homephone='(234)555-0033'; new.email='xyz@rosettacode.org'; new.directory='/home/xyz'; new.shell='/bin/bash';
%% append fid = fopen('passwd.txt','a+'); WriteRecord(fid,new); fclose(fid);
% read password file fid = fopen('passwd.txt','r'); while ~feof(fid)
printf('%s\n',fgetl(fid));
end; fclose(fid); </lang>
- Output:
jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz/bin/bash
Nim
<lang Nim>import posix import strutils
type
# GECOS representation. Gecos = tuple[fullname, office, extension, homephone, email: string]
# Record representation. Record = object account: string password: string uid: int gid: int gecos: Gecos directory: string shell: string
- ---------------------------------------------------------------------------------------------------
proc str(gecos: Gecos): string =
## Explicit representation of a GECOS.
result = "(" for name, field in gecos.fieldPairs: result.addSep(", ", 1) result.add(name & ": " & field) result.add(')')
- ---------------------------------------------------------------------------------------------------
proc `$`(gecos: Gecos): string =
## Compact representation of a GECOS.
for field in gecos.fields: result.addSep(",", 0) result.add(field)
- ---------------------------------------------------------------------------------------------------
proc parseGecos(s: string): Gecos =
## Parse a string and return a Gecos tuple.
let fields = s.split(",") result = (fields[0], fields[1], fields[2], fields[3], fields[4])
- ---------------------------------------------------------------------------------------------------
proc str(rec: Record): string =
## Explicit representation of a record.
for name, field in rec.fieldPairs: result.add(name & ": ") when typeof(field) is Gecos: result.add(str(field)) else: result.add($field) result.add('\n')
- ---------------------------------------------------------------------------------------------------
proc `$`(rec: Record): string =
# Compact representation fo a record.
for field in rec.fields: result.addSep(":", 0) result.add($field)
- ---------------------------------------------------------------------------------------------------
proc parseRecord(line: string): Record =
## Parse a string and return a Record object.
let fields = line.split(":") result.account = fields[0] result.password = fields[1] result.uid = fields[2].parseInt() result.gid = fields[3].parseInt() result.gecos = parseGecos(fields[4]) result.directory = fields[5] result.shell = fields[6]
- ---------------------------------------------------------------------------------------------------
proc getLock(f: File): bool =
## Try to get an exclusive write lock on file "f". Return false is unsuccessful.
var flock = TFlock(l_type: cshort(F_WRLCK), l_whence: cshort(SEEK_SET), l_start: 0, l_len: 0) result = f.getFileHandle().fcntl(F_SETLK, flock.addr) >= 0
- ———————————————————————————————————————————————————————————————————————————————————————————————————
var pwfile: File
const Filename = "passwd"
const Data = ["jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash",
"jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash"]
- Prepare initial file.
- We don'’t use a lock here as it is only the preparation.
pwfile = open(FileName, fmWrite) for line in Data:
pwfile.writeLine(line)
pwfile.close()
- Display initial contents.
echo "Raw content of initial password file:" echo "-------------------------------------" var records: seq[Record] for line in lines(FileName):
echo line records.add(line.parseRecord())
echo "" echo "Structured content of initial password file:" echo "--------------------------------------------" for rec in records:
echo str(rec)
- Add a new record at the end of password file.
pwfile = open(Filename, fmAppend) let newRecord = Record(account: "xyz",
password: "x", uid: 1003, gid: 1000, gecos: ("X Yz", "Room 1003", "(234)555-8913", "(234)555-0033", "xyz@rosettacode.org"), directory: "/home/xyz", shell: "/bin/bash")
echo "Appending new record:" echo "---------------------" echo str(newRecord) if pwfile.getLock():
pwFile.writeLine(newRecord) pwfile.close()
else:
echo "File is locked. Quitting." pwFile.close() quit(QuitFailure)
- Reopen the file and display its contents.
echo "Raw content of updated password file:" echo "-------------------------------------" for line in lines(FileName):
echo line</lang>
- Output:
Raw content of initial password file: ------------------------------------- jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash Structured content of initial password file: -------------------------------------------- account: jsmith password: x uid: 1001 gid: 1000 gecos: (fullname: Joe Smith, office: Room 1007, extension: (234)555-8917, homephone: (234)555-0077, email: jsmith@rosettacode.org) directory: /home/jsmith shell: /bin/bash account: jdoe password: x uid: 1002 gid: 1000 gecos: (fullname: Jane Doe, office: Room 1004, extension: (234)555-8914, homephone: (234)555-0044, email: jdoe@rosettacode.org) directory: /home/jdoe shell: /bin/bash Appending new record: --------------------- account: xyz password: x uid: 1003 gid: 1000 gecos: (fullname: X Yz, office: Room 1003, extension: (234)555-8913, homephone: (234)555-0033, email: xyz@rosettacode.org) directory: /home/xyz shell: /bin/bash Raw content of updated password file: ------------------------------------- jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Perl
The program uses flock(2) (or emulation, if flock is not available) to lock the file. <lang Perl>use strict; use warnings;
use Fcntl qw( :flock SEEK_END );
use constant {
RECORD_FIELDS => [qw( account password UID GID GECOS directory shell )], GECOS_FIELDS => [qw( fullname office extension homephone email )], RECORD_SEP => ':', GECOS_SEP => ',', PASSWD_FILE => 'passwd.txt',
};
- here's our three records
my $records_to_write = [
{ account => 'jsmith', password => 'x', UID => 1001, GID => 1000, GECOS => { fullname => 'John Smith', office => 'Room 1007', extension => '(234)555-8917', homephone => '(234)555-0077', email => 'jsmith@rosettacode.org', }, directory => '/home/jsmith', shell => '/bin/bash', }, { account => 'jdoe', password => 'x', UID => 1002, GID => 1000, GECOS => { fullname => 'Jane Doe', office => 'Room 1004', extension => '(234)555-8914', homephone => '(234)555-0044', email => 'jdoe@rosettacode.org', }, directory => '/home/jdoe', shell => '/bin/bash', },
]; my $record_to_append = {
account => 'xyz', password => 'x', UID => 1003, GID => 1000, GECOS => { fullname => 'X Yz', office => 'Room 1003', extension => '(234)555-8913', homephone => '(234)555-0033', email => 'xyz@rosettacode.org', }, directory => '/home/xyz', shell => '/bin/bash',
};
sub record_to_string {
my $rec = shift; my $sep = shift // RECORD_SEP; my $fields = shift // RECORD_FIELDS; my @ary; for my $field (@$fields) { my $r = $rec->{$field}; die "Field '$field' not found" unless defined $r; # simple sanity check push @ary, ( $field eq 'GECOS' ? record_to_string( $r, GECOS_SEP, GECOS_FIELDS ) : $r ); } return join $sep, @ary;
}
sub write_records_to_file {
my $records = shift; my $filename = shift // PASSWD_FILE; open my $fh, '>>', $filename or die "Can't open $filename: $!"; flock( $fh, LOCK_EX ) or die "Can't lock $filename: $!"; # if someone appended while we were waiting... seek( $fh, 0, SEEK_END ) or die "Can't seek $filename: $!" ; print $fh record_to_string($_), "\n" for @$records; flock( $fh, LOCK_UN ) or die "Can't unlock $filename: $!"; # note: the file is closed automatically when function returns (and refcount of $fh becomes 0)
}
- write two records to file
write_records_to_file( $records_to_write );
- append one more record to file
write_records_to_file( [$record_to_append] );
- test
{
use Test::Simple tests => 1;
open my $fh, '<', PASSWD_FILE or die "Can't open ", PASSWD_FILE, ": $!"; my @lines = <$fh>; chomp @lines; ok( $lines[-1] eq
'xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash',
"Appended record: $lines[-1]" );
} </lang>
Output:
1..1 ok 1 - Appended record: xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
File contents:
jsmith:x:1001:1000:John Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
Hash table | Text file | PerlIO | ☑ | ☑ | Advisory lock |
Note that flock uses advisory lock; some other program (if it doesn't use flock) can still unexpectedly write to the file.
Phix
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
sequence | text file | builtin | ☑ | ☑ | ☑ (Advisory lock) |
Locking is used to ensure multitasking safety. Note that on Phix, "multitasking" is the kid brother of multithreading, and the calls to task_yield() in the code that follows are there to respect the phix-specific definition of multiple tasks being in the same process, in which case locking does not make any real difference - because there is no task_yield() in a locked state. You can also test the locking when running multiple processes/threads by uncommenting the wait_key() lines. <lang Phix>constant filename = "passwd.txt" integer fn
constant
rec1 = {"jsmith","x",1001,1000,{"Joe Smith","Room 1007","(234)555-8917","(234)555-0077","jsmith@rosettacode.org"},"/home/jsmith","/bin/bash"}, rec2 = {"jdoe","x",1002,1000,{"Jane Doe","Room 1004","(234)555-8914","(234)555-0044","jdoe@rosettacode.org"},"/home/jdoe","/bin/bash"}, rec3 = {"xyz","x",1003,1000,{"X Yz","Room 1003","(234)555-8913","(234)555-0033","xyz@rosettacode.org"},"/home/xyz","/bin/bash"}
function tostring(sequence record)
record[3] = sprintf("%d",{record[3]}) record[4] = sprintf("%d",{record[4]}) record[5] = join(record[5],",") record = join(record,":") return record
end function
procedure wait(string what)
?sprintf("wait (%s)",{what}) sleep(1) task_yield()
end procedure
if not file_exists(filename) then fn = open(filename,"w") if fn!=-1 then -- (someone else just beat us to it?) printf(fn,"account:password:UID:GID:fullname,office,extension,homephone,email:directory:shell\n") printf(fn,"%s\n",{tostring(rec1)}) printf(fn,"%s\n",{tostring(rec2)}) close(fn) end if end if while 1 do fn = open(filename,"a") if fn!=-1 then exit end if wait("append") end while
-- ?"file open in append mode"; {} = wait_key()
while 1 do if lock_file(fn,LOCK_EXCLUSIVE,{}) then exit end if wait("lock") end while
-- ?"file locked"; {} = wait_key()
printf(fn,"%s\n",{tostring(rec3)}) unlock_file(fn,{}) close(fn) while 1 do fn = open(filename,"r") if fn!=-1 then exit end if wait("read") end while
?gets(fn) while 1 do object line = gets(fn) if atom(line) then exit end if ?line {line} = scanf(line,"%s:%s:%d:%d:%s:%s:%s\n") line[5] = split(line[5],',') ?line end while close(fn)</lang>
- Output:
"account:password:UID:GID:fullname,office,extension,homephone,email:directory:shell\n" "jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash\n" {"jsmith","x",1001,1000,{"Joe Smith","Room 1007","(234)555-8917","(234)555-0077","jsmith@rosettacode.org"},"/home/jsmith","/bin/bash"} "jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash\n" {"jdoe","x",1002,1000,{"Jane Doe","Room 1004","(234)555-8914","(234)555-0044","jdoe@rosettacode.org"},"/home/jdoe","/bin/bash"} "xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash\n" {"xyz","x",1003,1000,{"X Yz","Room 1003","(234)555-8913","(234)555-0033","xyz@rosettacode.org"},"/home/xyz","/bin/bash"}
Phixmonti
<lang Phixmonti>include ..\Utilitys.pmt
def ltos /# l -- s #/
"" >ps len for get string? not if number? if tostr else ltos "<ls>:" swap "</ls>" chain chain endif endif ps> swap chain ":" chain >ps endfor drop ps>
enddef
def stol /# s -- l #/
-1 del ":" xplit "<ls>" find 1 + snip "</ls>" find snip 1 del rot len >ps rot ps> set swap chain
enddef
( "jsmith" "x" 1001 1000 ( "Joe Smith" "Room 1007" "(234)555-8917" "(234)555-0077" "jsmith@rosettacode.org" ) "/home/jsmith" "/bin/bash" )
( "jdoe" "x" 1002 1000 ( "Jane Doe" "Room 1004" "(234)555-8914" "(234)555-0044" "jdoe@rosettacode.org" ) "/home/jdoe" "/bin/bash" )
swap
"passwd.txt" var file
file "w" fopen var f ltos 10 chain f fputs ltos 10 chain f fputs f fclose
( "xyz" "x" 1003 1000 ( "X Yz" "Room 1003" "(234)555-8913" "(234)555-0033" "xyz@rosettacode.org" ) "/home/xyz" "/bin/bash" )
file "a" fopen var f ltos 10 chain f fputs f fclose
file "r" fopen var f true while
f fgets number? if drop false else stol ? true endif
endwhile f fclose</lang>
- Output:
["jsmith", "x", "1001", "1000", ["Joe Smith", "Room 1007", "(234)555-8917", "(234)555-0077", "jsmith@rosettacode.org"], "/home/jsmith", "/bin/bash"] ["jdoe", "x", "1002", "1000", ["Jane Doe", "Room 1004", "(234)555-8914", "(234)555-0044", "jdoe@rosettacode.org"], "/home/jdoe", "/bin/bash"] ["xyz", "x", "1003", "1000", ["X Yz", "Room 1003", "(234)555-8913", "(234)555-0033", "xyz@rosettacode.org"], "/home/xyz", "/bin/bash"] === Press any key to exit ===
PHP
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
String, array or stream resource | Nearly anything | built-in | ☑ | ☐ | ☑ |
<lang PHP><?php
$filename = '/tmp/passwd';
$data = array(
'account:password:UID:GID:fullname,office,extension,homephone,email:directory:shell' . PHP_EOL, 'jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash' . PHP_EOL, 'jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash' . PHP_EOL,
); file_put_contents($filename, $data, LOCK_EX);
echo 'File contents before new record added:', PHP_EOL, file_get_contents($filename), PHP_EOL;
$data = array(
'xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash' . PHP_EOL
); file_put_contents($filename, $data, FILE_APPEND | LOCK_EX);
echo 'File contents after new record added:', PHP_EOL, file_get_contents($filename), PHP_EOL; </lang>
- Output:
File contents before new record added: account:password:UID:GID:fullname,office,extension,homephone,email:directory:shell jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash File contents after new record added: account:password:UID:GID:fullname,office,extension,homephone,email:directory:shell jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
PicoLisp
<lang PicoLisp>(setq L '((jsmith x 1001 1000
"Joe Smith,Room 1007,(234)555-8917,\ (234)555-0077,jsmith@rosettacode.org" /home/jsmith /bin/bash ) (jdoe x 1002 1000 "Jane Doe,Room 1004,(234)555-8914,\ (234)555-0044,jdoe@rosettacode.org" /home/jsmith /bin/bash ) ) )
(setq A '(xyz x 1003 1000
"X Yz,Room 1003,(234)555-8913,\ (234)555-0033,xyz@rosettacode.org" /home/xyz /bin/bash ) )
(out "mythical"
(for I L (prinl (glue ': I)) ) )
(out "+mythical"
(prinl (glue ': A)) )
(in "mythical"
(do 2 (line)) (println (and (= "xyz" (pack (till ':))) (= 3 (lines "mythical") ) ) ) )
(bye)</lang>
PowerShell
I treated the file as a CSV file without header information. File testing is minimal.
Since PowerShell loves to deal in objects I wrote extra code to better manipilate and display data. <lang PowerShell> function Test-FileLock {
Param ( [parameter(Mandatory=$true)] [string] $Path )
$outFile = New-Object System.IO.FileInfo $Path
if (-not(Test-Path -Path $Path)) { return $false }
try { $outStream = $outFile.Open([System.IO.FileMode]::Open, [System.IO.FileAccess]::ReadWrite, [System.IO.FileShare]::None)
if ($outStream) { $outStream.Close() }
return $false } catch { # File is locked by a process. return $true }
}
function New-Record {
Param ( [string]$Account, [string]$Password, [int]$UID, [int]$GID, [string]$FullName, [string]$Office, [string]$Extension, [string]$HomePhone, [string]$Email, [string]$Directory, [string]$Shell )
$GECOS = [PSCustomObject]@{ FullName = $FullName Office = $Office Extension = $Extension HomePhone = $HomePhone Email = $Email }
[PSCustomObject]@{ Account = $Account Password = $Password UID = $UID GID = $GID GECOS = $GECOS Directory = $Directory Shell = $Shell }
}
function Import-File
{
Param ( [Parameter(Mandatory=$false, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)] [string] $Path = ".\passwd.txt" )
if (-not(Test-Path $Path)) { throw [System.IO.FileNotFoundException] }
$header = "Account","Password","UID","GID","GECOS","Directory","Shell"
$csv = Import-Csv -Path $Path -Delimiter ":" -Header $header -Encoding ASCII $csv | ForEach-Object { New-Record -Account $_.Account ` -Password $_.Password ` -UID $_.UID ` -GID $_.GID ` -FullName $_.GECOS.Split(",")[0] ` -Office $_.GECOS.Split(",")[1] ` -Extension $_.GECOS.Split(",")[2] ` -HomePhone $_.GECOS.Split(",")[3] ` -Email $_.GECOS.Split(",")[4] ` -Directory $_.Directory ` -Shell $_.Shell }
}
function Export-File
{
[CmdletBinding()] Param ( [Parameter(Mandatory=$true, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)] $InputObject,
[Parameter(Mandatory=$false, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)] [string] $Path = ".\passwd.txt" )
Begin { if (-not(Test-Path $Path)) { New-Item -Path . -Name $Path -ItemType File | Out-Null }
[string]$recordString = "{0}:{1}:{2}:{3}:{4}:{5}:{6}" [string]$gecosString = "{0},{1},{2},{3},{4}" [string[]]$lines = @() [string[]]$file = Get-Content $Path } Process { foreach ($object in $InputObject) { $lines += $recordString -f $object.Account, $object.Password, $object.UID, $object.GID, $($gecosString -f $object.GECOS.FullName, $object.GECOS.Office, $object.GECOS.Extension, $object.GECOS.HomePhone, $object.GECOS.Email), $object.Directory, $object.Shell } } End { foreach ($line in $lines) { if (-not ($line -in $file)) { $line | Out-File -FilePath $Path -Encoding ASCII -Append } } }
} </lang> Create record objects. <lang PowerShell> $records = @()
$records+= New-Record -Account 'jsmith' `
-Password 'x' ` -UID 1001 ` -GID 1000 ` -FullName 'Joe Smith' ` -Office 'Room 1007' ` -Extension '(234)555-8917' ` -HomePhone '(234)555-0077' ` -Email 'jsmith@rosettacode.org' ` -Directory '/home/jsmith' ` -Shell '/bin/bash'
$records+= New-Record -Account 'jdoe' `
-Password 'x' ` -UID 1002 ` -GID 1000 ` -FullName 'Jane Doe' ` -Office 'Room 1004' ` -Extension '(234)555-8914' ` -HomePhone '(234)555-0044' ` -Email 'jdoe@rosettacode.org' ` -Directory '/home/jdoe' ` -Shell '/bin/bash'
</lang> Display record objects. <lang PowerShell> $records | Format-Table -AutoSize </lang>
- Output:
Account Password UID GID GECOS Directory Shell ------- -------- --- --- ----- --------- ----- jsmith x 1001 1000 @{FullName=Joe Smith; Office=Room 1007; Extension=(234)555-8917; HomePhone=(234)555-0077; Email=jsmith@rosettacode.org} /home/jsmith /bin/bash jdoe x 1002 1000 @{FullName=Jane Doe; Office=Room 1004; Extension=(234)555-8914; HomePhone=(234)555-0044; Email=jdoe@rosettacode.org} /home/jdoe /bin/bash
Export records to file. <lang PowerShell> if (-not(Test-FileLock -Path ".\passwd.txt")) {
$records | Export-File -Path ".\passwd.txt"
} </lang> This is the file. <lang PowerShell> Get-Content -Path ".\passwd.txt" </lang>
- Output:
jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash
Add a record to the record set. <lang PowerShell> $records+= New-Record -Account 'xyz' `
-Password 'x' ` -UID 1003 ` -GID 1000 ` -FullName 'X Yz' ` -Office 'Room 1003' ` -Extension '(234)555-8913' ` -HomePhone '(234)555-0033' ` -Email 'xyz@rosettacode.org' ` -Directory '/home/xyz' ` -Shell '/bin/bash'
</lang> Display record objects, sorted on last name; and display them. <lang PowerShell> $records | Sort-Object { $_.GECOS.FullName.Split(" ")[1] } | Format-Table -AutoSize </lang>
- Output:
Account Password UID GID GECOS Directory Shell ------- -------- --- --- ----- --------- ----- jdoe x 1002 1000 @{FullName=Jane Doe; Office=Room 1004; Extension=(234)555-8914; HomePhone=(234)555-0044; Email=jdoe@rosettacode.org} /home/jdoe /bin/bash jsmith x 1001 1000 @{FullName=Joe Smith; Office=Room 1007; Extension=(234)555-8917; HomePhone=(234)555-0077; Email=jsmith@rosettacode.org} /home/jsmith /bin/bash xyz x 1003 1000 @{FullName=X Yz; Office=Room 1003; Extension=(234)555-8913; HomePhone=(234)555-0033; Email=xyz@rosettacode.org} /home/xyz /bin/bash
Export records to file. <lang PowerShell> if (-not(Test-FileLock -Path ".\passwd.txt")) {
$records | Export-File -Path ".\passwd.txt"
} </lang> This is the file. <lang PowerShell> Get-Content -Path ".\passwd.txt" </lang>
- Output:
jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
PSCustomObject | (CSV?) text file | Built-in (.NET) | ☑ | ☑ | ☑ (High probability) |
Python
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
dict | CSV text file | builtin | ☑ | ☑ | ☒ |
instance | CSV text file | builtin | To do. |
From a "dict" to a CSV File <lang python>#############################
- Create a passwd text file
- note that UID & gid are of type "text"
passwd_list=[
dict(account='jsmith', password='x', UID=1001, GID=1000, # UID and GID are type int GECOS=dict(fullname='Joe Smith', office='Room 1007', extension='(234)555-8917', homephone='(234)555-0077', email='jsmith@rosettacode.org'), directory='/home/jsmith', shell='/bin/bash'), dict(account='jdoe', password='x', UID=1002, GID=1000, GECOS=dict(fullname='Jane Doe', office='Room 1004', extension='(234)555-8914', homephone='(234)555-0044', email='jdoe@rosettacode.org'), directory='/home/jdoe', shell='/bin/bash')
]
passwd_fields="account password UID GID GECOS directory shell".split() GECOS_fields="fullname office extension homephone email".split()
def passwd_text_repr(passwd_rec):
- convert individual fields to string type
passwd_rec["GECOS"]=",".join([ passwd_rec["GECOS"][field] for field in GECOS_fields]) for field in passwd_rec: # convert "int" fields if not isinstance(passwd_rec[field], str): passwd_rec[field]=`passwd_rec[field]` return ":".join([ passwd_rec[field] for field in passwd_fields ])
passwd_text=open("passwd.txt","w") for passwd_rec in passwd_list:
print >> passwd_text,passwd_text_repr(passwd_rec)
passwd_text.close()
- Load text ready for appending
passwd_text=open("passwd.txt","a+") new_rec=dict(account='xyz', password='x', UID=1003, GID=1000,
GECOS=dict(fullname='X Yz', office='Room 1003', extension='(234)555-8913', homephone='(234)555-0033', email='xyz@rosettacode.org'), directory='/home/xyz', shell='/bin/bash')
print >> passwd_text, passwd_text_repr(new_rec) passwd_text.close()
- Finally reopen and check record was appended
passwd_list=list(open("passwd.txt","r")) if "xyz" in passwd_list[-1]:
print "Appended record:",passwd_list[-1][:-1]</lang>
- Output:
Appended record: xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Racket
The simplest format for such data in plain text is S-expression.
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
S-exprs | text file | builtin | ☑ | ☑ | ☑ |
<lang racket>
- lang racket
(define sample1
'("jsmith" "x" 1001 1000 ("Joe Smith" "Room 1007" "(234)555-8917" "(234)555-0077" "jsmith@rosettacode.org") "/home/jsmith" "/bin/bash"))
(define sample2
'("jdoe" "x" 1002 1000 ("Jane Doe" "Room 1004" "(234)555-8914" "(234)555-0044" "jdoe@rosettacode.org") "/home/jdoe" "/bin/bash"))
(define sample3
'("xyz" "x" 1003 1000 ("X Yz" "Room 1003" "(234)555-8913" "(234)555-0033" "xyz@rosettacode.org") "/home/xyz" "/bin/bash"))
(define passwd-file "sexpr-passwd")
(define (write-passwds mode . ps)
(with-output-to-file passwd-file #:exists mode (λ() (for ([p (in-list ps)]) (printf "~s\n" p)))))
(define (lookup username)
(with-input-from-file passwd-file (λ() (for/first ([p (in-producer read eof)] #:when (equal? username (car p))) p))))
(printf "Creating file with two sample records.\n") (write-passwds 'replace sample1 sample2)
(printf "Appending third sample.\n") (write-passwds 'append sample3)
(printf "Looking up xyz in current file:\n=> ~s\n" (lookup "xyz")) </lang>
- Output:
Creating file with two sample records. Appending third sample. Looking up xyz in current file: => ("xyz" "x" 1003 1000 ("X Yz" "Room 1003" "(234)555-8913" "(234)555-0033" "xyz@rosettacode.org") "/home/xyz" "/bin/bash")
Raku
(formerly Perl 6)
This is kind of silly as it takes a string, converts it to a record, and then instantly converts it back to a string to write out to a file. Most of the "record handling" code is just demonstrating a possible way to store records in memory. It really has nothing to do with appending a string to a file.
<lang perl6>class record {
has $.name; has $.password; has $.UID; has $.GID; has $.fullname; has $.office; has $.extension; has $.homephone; has $.email; has $.directory; has $.shell;
method gecos { join ',', $.fullname, $.office, $.extension, $.homephone, $.email }
method gist { join ':', $.name, $.password, $.UID, $.GID, self.gecos, $.directory, $.shell; }
};
my $fname = 'foo.fil';
given $fname.IO.open(:w) { .close }; # clear file
sub append ($file, $line){
my $fh = $file.IO.open(:a) or fail "Unable to open $file"; given $fh { # Get a lock on the file, waits until lock is active .lock; # seek to the end in case some other process wrote to # the file while we were waiting for the lock .seek(0, SeekType::SeekFromEnd); # write the record .say: $line; .close; }
}
sub str-to-record ($str) {
my %rec = <name password UID GID fullname office extension homephone email directory shell> Z=> $str.split(/<[:,]>/); my $user = record.new(|%rec);
}
for
'jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash', 'jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash'
-> $line {
my $thisuser = str-to-record $line; $fname.&append: $thisuser.gist;
}
put "Last line of $fname before append:"; put $fname.IO.lines.tail;
$fname.&append: str-to-record('xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash').gist;
put "Last line of $fname after append:"; put $fname.IO.lines.tail; </lang>
- Output:
Last line of foo.fil before append: jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash Last line of foo.fil after append: xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
Class | Text file | Whichever is provided by the underlying VM |
☑ | ☑ | ☑ Advisory lock Depends on OS and VM |
Note that advisory locks do not prevent some other program (if it doesn't use flock) from unexpectedly writing to the file.
RapidQ
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
QObject | CSV text file | Standard lib | ☑ | ☑ | ☑ |
The easy short solution <lang vb> 'Short solution: Append record and read last record $Include "Rapidq.inc"
dim file as qfilestream dim filename as string dim LogRec as string
'First create our logfile filename = "C:\Logfile2.txt" file.open(filename, fmCreate) file.writeline "jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash" file.writeline "jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jsmith:/bin/bash" file.close
'Append record file.open(filename, fmOpenWrite) file.position = File.size file.writeline "xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash" file.close
'Read last record file.open (filename, fmOpenRead) while not file.EOF
LogRec = File.Readline
wend file.close
showmessage "Appended record: " + LogRec </lang>
- Output:
Appended record: xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Full solution: create an object to handle all functions <lang vb> 'Full solution: Create an object with all required fields and 'build-in functions to append a record and to read the last record $include "Rapidq.inc"
Type TLogFile extends QObject
Private: file as qfilestream Public: account as string password as string UID as integer GID as integer GECOS.fullname as string GECOS.office as string GECOS.extension as string GECOS.homephone as string GECOS.email as string directory as string shell as string RSep as string GSep as string function AppendRecord(LogFile as string) as integer with This if fileexists(LogFile) then Result = .file.open(LogFile, fmOpenWrite) else Result = .file.open(LogFile, fmCreate) end if .file.position = .file.size .file.writeline .account + .RSep + .password + .RSep + str$(.UID) + .RSep + str$(.GID) + .RSep +_ .GECOS.fullname + .GSep + .GECOS.office + .GSep + .GECOS.extension +_ .GSep + .GECOS.homephone + .GSep + .GECOS.email + .RSep +_ .directory + .RSep + .shell .file.close end with end function Function ReadLastRecord(LogFile as string) as string dim x as integer dim LogRec as string dim GECOSRec as string With This if fileexists(LogFile) then .file.open(LogFile, fmOpenRead) While not .file.eof LogRec = .file.readline Wend .file.close .account = field$(LogRec, .RSep, 1) .password = field$(LogRec, .RSep, 2) .UID = val(field$(LogRec, .RSep, 3)) .GID = val(field$(LogRec, .RSep, 4)) GECOSRec = field$(LogRec, .RSep, 5) .directory = field$(LogRec, .RSep, 6) .shell = field$(LogRec, .RSep, 7) .GECOS.fullname = field$(GECOSRec, .GSep, 1) .GECOS.office = field$(GECOSRec, .GSep, 2) .GECOS.extension = field$(GECOSRec, .GSep, 3) .GECOS.homephone = field$(GECOSRec, .GSep, 4) .GECOS.email = field$(GECOSRec, .GSep, 5) else showmessage "Can't read file " + Logfile
end if end with End function Constructor RSep = ":" GSep = "," End Constructor
end type
'--- Now we can use our LogFile object: dim LogFile as TLogFile
'--- Let's save a record: Set field values Logfile.account = "jsmith" Logfile.password = "X" Logfile.UID = 1001 Logfile.GID = 1000 Logfile.directory = "/home/jsmith" Logfile.shell = "/bin/bash" Logfile.GECOS.fullname = "Joe Smith" Logfile.GECOS.office = "Room 1007" Logfile.GECOS.extension = "(234)555-8917" Logfile.GECOS.homephone = "(234)555-0077" Logfile.GECOS.email = "jsmith@rosettacode.org" '--- And save it to our logfile Logfile.appendrecord("c:\A test.txt")
'--- Let's save the second one: Set field values Logfile.account = "jdoe" Logfile.password = "X" Logfile.UID = 1002 Logfile.GID = 1000 Logfile.directory = "/home/jsmith" Logfile.shell = "/bin/bash" Logfile.GECOS.fullname = "Jane Doe" Logfile.GECOS.office = "Room 1004" Logfile.GECOS.extension = "(234)555-8914" Logfile.GECOS.homephone = "(234)555-0044" Logfile.GECOS.email = "jdoe@rosettacode.org" '--- And save it to our logfile Logfile.appendrecord("c:\A test.txt")
'--- And append the last one: Set field values Logfile.account = "xyz" Logfile.password = "X" Logfile.UID = 1003 Logfile.GID = 1000 Logfile.directory = "/home/xyz" Logfile.shell = "/bin/bash" Logfile.GECOS.fullname = "X Yz" Logfile.GECOS.office = "Room 1003" Logfile.GECOS.extension = "(234)555-8913" Logfile.GECOS.homephone = "(234)555-0033" Logfile.GECOS.email = "xyz@rosettacode.org" '--- And save it to our logfile Logfile.appendrecord("c:\A test.txt")
'--- Read last record: load all CSV fields in our LogFile object props
Logfile.ReadLastRecord("c:\A test.txt")
'--- And simply Read values from the objects properties
Print Logfile.account
Print Logfile.password
Print Logfile.UID
Print Logfile.GID
Print Logfile.directory
Print Logfile.shell
Print Logfile.GECOS.fullname
Print Logfile.GECOS.office
Print Logfile.GECOS.extension
Print Logfile.GECOS.homephone
Print Logfile.GECOS.email
Print ""
input "Press enter to exit:";a$
</lang>
REXX
data representation | I/O library |
append |
automatic append |
multi-tasking safe | |
---|---|---|---|---|---|
in memory | on disk | ||||
strings | text file | builtin | yes | yes | yes |
The data fields for the three records were coded on two statements instead of
continuing them on separate statements for brevity.
<lang rexx>/*REXX program writes (appends) two records, closes the file, appends another record.*/
tFID= 'PASSWD.TXT' /*define the name of the output file.*/
call lineout tFID /*close the output file, just in case,*/
/* it could be open from calling pgm.*/
call writeRec tFID,, /*append the 1st record to the file. */
'jsmith',"x", 1001, 1000, 'Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org', "/home/jsmith", '/bin/bash'
call writeRec tFID,, /*append the 2nd record to the file. */
'jdoe', "x", 1002, 1000, 'Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org', "/home/jsmith", '/bin/bash'
call lineout fid /*close the outfile (just to be tidy).*/
call writeRec tFID,, /*append the 3rd record to the file. */
'xyz', "x", 1003, 1000, 'X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org', "/home/xyz", '/bin/bash'
/*─account─pw────uid───gid──────────────fullname,office,extension,homephone,Email────────────────────────directory───────shell──*/
call lineout fid /*"be safe" programming: close the file*/ exit /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ s: if arg(1)==1 then return arg(3); return word(arg(2) 's', 1) /*pluralizer*/ /*──────────────────────────────────────────────────────────────────────────────────────*/ writeRec: parse arg fid,_ /*get the fileID, and also the 1st arg.*/
sep=':' /*field delimiter used in file, it ··· */ /* ··· can be unique and any size.*/ do i=3 to arg() /*get each argument and append it to */ _=_ || sep || arg(i) /* the previous arg, with a : sep.*/ end /*i*/
do tries=0 for 11 /*keep trying for 66 seconds. */ r=lineout(fid, _) /*write (append) the new record. */ if r==0 then return /*Zero? Then record was written. */ call sleep tries /*Error? So try again after a delay. */ end /*tries*/ /*Note: not all REXXes have SLEEP. */
say '***error***'; say r 'record's(r) "not written to file" fid; exit 13 /*some error causes: no write access, disk is full, file lockout, no authority*/</lang>
PASSWD.TXT file before the REXX program ran:
:::::::::::::::::::::::::::::::::::::::: Hopefully, this will be considered a comment.
PASSWD.TXT file after the REXX program ran:
:::::::::::::::::::::::::::::::::::::::: Hopefully, this will be considered a comment. jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jsmith:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Ruby
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
objects (subclass of Struct builtin) | text file | builtin | ☑ | ☑ | ☒ |
<lang ruby>Gecos = Struct.new :fullname, :office, :extension, :homephone, :email class Gecos
def to_s "%s,%s,%s,%s,%s" % to_a end
end
- Another way define 'to_s' method
Passwd = Struct.new(:account, :password, :uid, :gid, :gecos, :directory, :shell) do
def to_s to_a.join(':') end
end
jsmith = Passwd.new('jsmith','x',1001, 1000, Gecos.new('Joe Smith', 'Room 1007', '(234)555-8917', '(234)555-0077', 'jsmith@rosettacode.org'), '/home/jsmith', '/bin/bash') jdoe = Passwd.new('jdoe','x',1002, 1000, Gecos.new('Jane Doe', 'Room 1004', '(234)555-8914', '(234)555-0044', 'jdoe@rosettacode.org'), '/home/jdoe', '/bin/bash') xyz = Passwd.new('xyz','x',1003, 1000, Gecos.new('X Yz', 'Room 1003', '(234)555-8913', '(234)555-0033', 'xyz@rosettacode.org'), '/home/xyz', '/bin/bash')
filename = 'append.records.test'
- create the passwd file with two records
File.open(filename, 'w') do |io|
io.puts jsmith io.puts jdoe
end
puts "before appending:" puts File.readlines(filename)
- append the third record
File.open(filename, 'a') do |io|
io.puts xyz
end
puts "after appending:" puts File.readlines(filename)</lang>
- Output:
before appending: jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash after appending: jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Rust
<lang rust> use std::fs::File; use std::fs::OpenOptions; use std::io::BufRead; use std::io::BufReader; use std::io::BufWriter; use std::io::Result; use std::io::Write; use std::path::Path;
/// Password record with all fields
- [derive(Eq, PartialEq, Debug)]
pub struct PasswordRecord {
pub account: String, pub password: String, pub uid: u64, pub gid: u64, pub gecos: Vec<String>, pub directory: String, pub shell: String,
}
impl PasswordRecord {
/// new instance, cloning all fields pub fn new( account: &str, password: &str, uid: u64, gid: u64, gecos: Vec<&str>, directory: &str, shell: &str, ) -> PasswordRecord { PasswordRecord { account: account.to_string(), password: password.to_string(), uid, gid, gecos: gecos.iter().map(|s| s.to_string()).collect(), directory: directory.to_string(), shell: shell.to_string(), } }
/// convert to one line string pub fn to_line(&self) -> String { let gecos = self.gecos.join(","); format!( "{}:{}:{}:{}:{}:{}:{}", self.account, self.password, self.uid, self.gid, gecos, self.directory, self.shell ) }
/// read record from line pub fn from_line(line: &str) -> PasswordRecord { let sp: Vec<&str> = line.split(":").collect(); if sp.len() < 7 { panic!("Less than 7 fields found"); } else { let uid = sp[2].parse().expect("Cannot parse uid"); let gid = sp[3].parse().expect("Cannot parse gid"); let gecos = sp[4].split(",").collect(); PasswordRecord::new(sp[0], sp[1], uid, gid, gecos, sp[5], sp[6]) } }
}
/// read all records from file pub fn read_password_file(file_name: &str) -> Result<Vec<PasswordRecord>> {
let p = Path::new(file_name); if !p.exists() { Ok(vec![]) } else { let f = OpenOptions::new().read(true).open(p)?; Ok(BufReader::new(&f) .lines() .map(|l| PasswordRecord::from_line(&l.unwrap())) .collect()) }
}
/// overwrite file with records pub fn overwrite_password_file(file_name: &str, recs: &Vec<PasswordRecord>) -> Result<()> {
let f = OpenOptions::new() .create(true) .write(true) .open(file_name)?; write_records(f, recs)
}
/// append records to file pub fn append_password_file(file_name: &str, recs: &Vec<PasswordRecord>) -> Result<()> {
let f = OpenOptions::new() .create(true) .append(true) .open(file_name)?; write_records(f, recs)
}
/// internal, write records line by line fn write_records(f: File, recs: &Vec<PasswordRecord>) -> Result<()> {
let mut writer = BufWriter::new(f); for rec in recs { write!(writer, "{}\n", rec.to_line())?; } Ok(())
}
fn main(){
let recs1 = vec![ PasswordRecord::new( "jsmith", "x", 1001, 1000, vec![ "Joe Smith", "Room 1007", "(234)555-8917", "(234)555-0077", "jsmith@rosettacode.org", ], "/home/jsmith", "/bin/bash", ), PasswordRecord::new( "jdoe", "x", 1002, 1000, vec![ "Jane Doe", "Room 1004", "(234)555-8914", "(234)555-0044", "jdoe@rosettacode.org", ], "/home/jdoe", "/bin/bash", ), ];
overwrite_password_file("passwd", &recs1).expect("cannot write file"); let recs2 = read_password_file("passwd").expect("cannot read file"); println!("Original file:"); for r in recs2 { println!("{}",r.to_line()); } let append0 = vec![PasswordRecord::new( "xyz", "x", 1003, 1000, vec![ "X Yz", "Room 1003", "(234)555-8913", "(234)555-0033", "xyz@rosettacode.org", ], "/home/xyz", "/bin/bash", )]; append_password_file("passwd", &append0).expect("cannot append to file"); let recs2 = read_password_file("passwd").expect("cannot read file"); println!(""); println!("Appended file:"); for r in recs2 { println!("{}",r.to_line()); }
} </lang>
- Output:
Original file: jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash Appended file: jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Scala
<lang scala>import java.io.{File, FileWriter, IOException}
import scala.io.Source
object RecordAppender extends App {
val rawDataIt = Source.fromString(rawData).getLines()
def writeStringToFile(file: File, data: String, appending: Boolean = false) = using(new FileWriter(file, appending))(_.write(data))
def using[A <: {def close() : Unit}, B](resource: A)(f: A => B): B = try f(resource) finally resource.close()
def rawData = """jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash |jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash |xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash""".stripMargin
case class Record(account: String, password: String, uid: Int, gid: Int, gecos: Array[String], directory: String, shell: String) { def asLine: String = s"$account:$password:$uid:$gid:${gecos.mkString(",")}:$directory:$shell\n" }
object Record { def apply(line: String): Record = { val token = line.trim.split(":") require((token != null) || (token.length == 7)) this(token(0).trim, token(1).trim, Integer.parseInt(token(2).trim), Integer.parseInt(token(3).trim), token(4).split(","), token(5).trim, token(6).trim) } }
try { val file = File.createTempFile("_rosetta", ".passwd") using(new FileWriter(file))(writer => rawDataIt.take(2).foreach(line => writer.write(Record(line).asLine)))
writeStringToFile(file, Record(rawDataIt.next()).asLine, appending = true) // Append a record
Source.fromFile(file).getLines().foreach(line => { if (line startsWith """xyz""") print(s"Selected record: ${Record(line).asLine}") }) scala.compat.Platform.collectGarbage() // JVM Windows related bug workaround JDK-4715154 file.deleteOnExit() } catch { case e: IOException => println(s"Running Example failed: ${e.getMessage}") }
} // 57 lines</lang>
Sidef
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
Hash table | Text file | built-in | ☑ | ☑ | Advisory lock |
<lang ruby>define (
RECORD_FIELDS = %w(account password UID GID GECOS directory shell), GECOS_FIELDS = %w(fullname office extension homephone email), RECORD_SEP = ':', GECOS_SEP = ',', PASSWD_FILE = 'passwd.txt',
)
- here's our three records
var records_to_write = [
Hash( account => 'jsmith', password => 'x', UID => 1001, GID => 1000, GECOS => Hash( fullname => 'John Smith', office => 'Room 1007', extension => '(234)555-8917', homephone => '(234)555-0077', email => 'jsmith@rosettacode.org', ), directory => '/home/jsmith', shell => '/bin/bash', ), Hash( account => 'jdoe', password => 'x', UID => 1002, GID => 1000, GECOS => Hash( fullname => 'Jane Doe', office => 'Room 1004', extension => '(234)555-8914', homephone => '(234)555-0044', email => 'jdoe@rosettacode.org', ), directory => '/home/jdoe', shell => '/bin/bash', ),
];
var record_to_append = Hash(
account => 'xyz', password => 'x', UID => 1003, GID => 1000, GECOS => Hash( fullname => 'X Yz', office => 'Room 1003', extension => '(234)555-8913', homephone => '(234)555-0033', email => 'xyz@rosettacode.org', ), directory => '/home/xyz', shell => '/bin/bash',
);
func record_to_string(rec, sep = RECORD_SEP, fields = RECORD_FIELDS) {
gather { fields.each { |field| var r = rec{field} \\ die "Field #{field} not found" take(field == 'GECOS' ? record_to_string(r, GECOS_SEP, GECOS_FIELDS) : r) } }.join(sep)
}
func write_records_to_file(records, filename = PASSWD_FILE, append = false) {
File(filename).(append ? :open_a : :open_w)(\var fh, \var err) err && die "Can't open #{filename}: #{err}"; fh.flock(File.LOCK_EX) || die "Can't lock #{filename}: $!" fh.seek(0, File.SEEK_END) || die "Can't seek #{filename}: $!" records.each { |record| fh.say(record_to_string(record)) } fh.flock(File.LOCK_UN) || die "Can't unlock #{filename}: $!" fh.close
}
- write two records to file
write_records_to_file(records: records_to_write);
- append one more record to file
write_records_to_file(records: [record_to_append], append: true);
- test
File(PASSWD_FILE).open_r(\var fh, \var err) err && die "Can't open file #{PASSWD_FILE}: #{err}" var lines = fh.lines
- There should be more than one line
assert(lines.len > 1)
- Check the last line
assert_eq(lines[-1], 'xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,' +
'(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash')
say "** Test passed!"</lang>
Note that flock uses advisory lock; some other program (if it doesn't use flock) can still unexpectedly write to the file.
Tcl
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
nested lists | Colon/Comma-separated text file | builtin | ☑ | ☑ | ☑ |
Note that appending is only safe on POSIX OSes where the data is written in “small enough” amounts to a local disk. This is a limitation of the OS APIs. <lang tcl># Model the data as nested lists, as that is a natural fit for Tcl set basicRecords {
{
jsmith x 1001 1000 { {Joe Smith} {Room 1007} (234)555-8917 (234)555-0077 jsmith@rosettacode.org } /home/jsmith /bin/bash
} {
jdoe x 1002 1000 { {Jane Doe} {Room 1004} (234)555-8914 (234)555-0044 jdoe@rosettacode.org } /home/jsmith /bin/bash
}
} set addedRecords {
{
xyz x 1003 1000 { {X Yz} {Room 1003} (234)555-8913 (234)555-0033 xyz@rosettacode.org } /home/xyz /bin/bash
}
}
proc printRecords {records fd} {
fconfigure $fd -buffering none foreach record $records {
lset record 4 [join [lindex $record 4] ","] puts -nonewline $fd [join $record ":"]\n
}
} proc readRecords fd {
set result {} foreach line [split [read $fd] "\n"] {
if {$line eq ""} continue set record [split $line ":"] # Special handling for GECOS lset record 4 [split [lindex $record 4] ","] lappend result $record
} return $result
}
- Write basic set
set f [open ./passwd w] printRecords $basicRecords $f close $f
- Append the extra ones
- Use {WRONLY APPEND} on Tcl 8.4
set f [open ./passwd a] printRecords $addedRecords $f close $f
set f [open ./passwd] set recs [readRecords $f] close $f
puts "last record is for [lindex $recs end 0], named [lindex $recs end 4 0]"</lang>
- Output:
last record is for xyz, named X Yz
The file will have this content:
jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jsmith:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
UNIX Shell
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
one-dimensional arrays (indexed or associative) | text file | builtin (shell redirections) | ☑ | ☑ | OS defined |
<lang bash>rec1=(
jsmith x 1001 1000 "Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org" /home/jsmith /bin/bash
)
rec2=(
jdoe x 1002 1000 "Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org" /home/jdoe /bin/bash
)
rec3=(
xyz x 1003 1000 "X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org" /home/xyz /bin/bash
)
filename=./passwd-ish
- use parentheses to run the commands in a subshell, so the
- current shell's IFS variable is not changed
(
IFS=: echo "${rec1[*]}" echo "${rec2[*]}"
) > "$filename"
echo before appending: cat "$filename"
- appending, use the ">>" redirection symbol
IFS=: echo "${rec3[*]}" >> "$filename"
echo after appending: cat "$filename"</lang>
- Output:
before appending: jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash after appending: jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Ursa
<lang ursa># ursa appends to files by default when the out function is used
- create new passwd in working directory
decl file f f.create "passwd" f.open "passwd" out "account:password:UID:GID:fullname,office,extension,homephone,email:directory:shell" endl f out "jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash" endl f out "jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash" endl f f.close
- display the created file
f.open "passwd" out "initial file:" endl console while (f.hasline) out (in string f) endl console end while
- append the new record
out "xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash" endl f f.close
- output the new file contents
f.open "passwd" out endl endl "file after append:" endl console while (f.hasline) out (in string f) endl console end while</lang>
Visual Basic .NET
<lang vbnet>Imports System.IO
Module Module1
Class PasswordRecord Public account As String Public password As String Public fullname As String Public office As String Public extension As String Public homephone As String Public email As String Public directory As String Public shell As String Public UID As Integer Public GID As Integer
Public Sub New(account As String, password As String, UID As Integer, GID As Integer, fullname As String, office As String, extension As String, homephone As String, email As String, directory As String, shell As String) Me.account = account Me.password = password Me.UID = UID Me.GID = GID Me.fullname = fullname Me.office = office Me.extension = extension Me.homephone = homephone Me.email = email Me.directory = directory Me.shell = shell End Sub
Public Overrides Function ToString() As String Dim gecos = String.Join(",", New String() {fullname, office, extension, homephone, email}) Return String.Join(":", New String() {account, password, UID.ToString(), GID.ToString(), gecos, directory, shell}) End Function End Class
Sub Main() Dim jsmith As New PasswordRecord("jsmith", "x", 1001, 1000, "Joe Smith", "Room 1007", "(234)555-8917", "(234)555-0077", "jsmith@rosettacode.org", "/home/jsmith", "/bin/bash") Dim jdoe As New PasswordRecord("jdoe", "x", 1002, 1000, "Jane Doe", "Room 1004", "(234)555-8914", "(234)555-0044", "jdoe@rosettacode.org", "/home/jdoe", "/bin/bash") Dim xyz As New PasswordRecord("xyz", "x", 1003, 1000, "X Yz", "Room 1003", "(234)555-8913", "(234)555-0033", "xyz@rosettacode.org", "/home/xyz", "/bin/bash")
' Write these records out in the typical system format. File.WriteAllLines("passwd.txt", New String() {jsmith.ToString(), jdoe.ToString()})
' Append a new record to the file and close the file again. File.AppendAllText("passwd.txt", xyz.ToString())
' Open the file and demonstrate the new record has indeed been written to the end. Dim lines = File.ReadAllLines("passwd.txt") Console.WriteLine("Appended record: {0}", lines(2)) End Sub
End Module</lang>
- Output:
Appended record: xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
Wren
Although Wren has basic classes to work with the file system, these are only available when creating standalone scripts using the command line interpreter (CLI) and not when Wren is being embedded. In the latter case it relies on the host application for such support.
To append a record to an existing file in a CLI script, a little digging is required as the method to do this (File.openWithFlags) is currently undocumented. However, the following works fine. <lang ecmascript>import "io" for File, FileFlags
var records = [
"jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,[email protected]:/home/jsmith:/bin/bash", "jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,[email protected]:/home/jdoe:/bin/bash"
]
// Write records to a new file called "passwd.csv" and close it. var fileName = "passwd.csv" File.create(fileName) {|file|
records.each { |r| file.writeBytes(r + "\n") }
}
// Check file has been created correctly. var contents = File.read(fileName) System.print("Initial records:\n") System.print(contents)
var newRec = "xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,[email protected]:/home/xyz:/bin/bash"
// Append the new record to the file and close it. File.openWithFlags(fileName, FileFlags.writeOnly) { |file|
file.writeBytes(newRec + "\n")
}
// Check the new record has been appended correctly. contents = File.read(fileName) System.print("Records after appending new one:\n") System.print(contents)</lang>
- Output:
Initial records: jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,[email protected]:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,[email protected]:/home/jdoe:/bin/bash Records after appending new one: jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,[email protected]:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,[email protected]:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,[email protected]:/home/xyz:/bin/bash
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
Wren string / class | CSV text file | Wren io module / libuv | ☑ | ☒ | ☑ (AFAIK) |
Yabasic
<lang Yabasic>a = open("passwd", "a") // Open the file for appending, i.e. what you write to the file will be appended after its initial contents.
// If the file does not exist, it will be created.
print #a "account:password:UID:GID:fullname,office,extension,homephone,email:directory:shell" print #a "jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash" print #a "jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash"
close #a
a = open("passwd", "a")
if not a error "Could not open 'passwd' for appending"
print #a "xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash"
close #a
if (not open(a,"passwd")) error "Could not open 'passwd' for reading"
dim nameField$(1), contentField$(1)
line input #a a$
n = token(a$, nameField$(), ":,") for i = 1 to n
if nameField$(i) = "account" field1 = i if nameField$(i) = "homephone" field2 = i
next
print upper$(nameField$(field1)), "\t", upper$(nameField$(field2)) print
while(not eof(#a))
line input #a a$ n = token(a$, contentField$(), ":,") print contentField$(field1), "\t", contentField$(field2)
wend
close #a</lang>
zkl
Data Representation | IO Library |
Append Possible |
Automatic Append |
Multi-tasking Safe | |
---|---|---|---|---|---|
In core | On disk | ||||
classes | text file | libc | ☑ | ☑ | OS defined |
<lang zkl>var [const]
gnames=T("fullname","office","extension","homephone","email"), pnames=T("account","password","uid","gid","gecos","directory","shell");
class Gecos{
var fullname, office, extension, homephone, email; fcn init(str){ gnames.zipWith(setVar,vm.arglist) } fcn toString { gnames.apply(setVar).concat(",") }
} class Passwd{
var account,password,uid,gid,gecos,directory,shell; fcn init(str){ pnames.zipWith(setVar,vm.arglist) } fcn toString { pnames.apply(setVar).concat(":") }
}</lang> The class setVar method takes one or two parameters. With two, it sets the named class variable to a value; with one, it gets the var. If there aren't enough parameters, the missing ones with be set to Void (yeah, poor error checking). <lang zkl>fcn strToPasswd(str){ // blow apart file line to class
p:=str.strip().split(":"); g:=Gecos(p[4].split(",").xplode()); Passwd(p[0,4].xplode(),g,p[5,*].xplode());
}</lang> The List xplode method pushes the list contents to the parameter list. <lang zkl>jsmith:=Passwd("jsmith","x",1001, 1000, Gecos("Joe Smith", "Room 1007", "(234)555-8917", "(234)555-0077", "jsmith@rosettacode.org"), "/home/jsmith", "/bin/bash"); jdoe:=strToPasswd("jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,"
"jdoe@rosettacode.org:/home/jdoe:/bin/bash");
xyz:=strToPasswd("xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,"
"xyz@rosettacode.org:/home/xyz:/bin/bash");
filename:="append.records.test"; f:=File(filename,"w"); // create file with 2 records f.writeln(jsmith,"\n",jdoe); f.close();
f:=File(filename,"a+"); // append a third record f.writeln(xyz); f.close();
File(filename).read().text.print(); // print file</lang>
- Output:
jsmith:x:1001:1000:Joe Smith,Room 1007,(234)555-8917,(234)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash jdoe:x:1002:1000:Jane Doe,Room 1004,(234)555-8914,(234)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash xyz:x:1003:1000:X Yz,Room 1003,(234)555-8913,(234)555-0033,xyz@rosettacode.org:/home/xyz:/bin/bash
- Programming Tasks
- File handling
- AWK
- Batch File
- C
- C sharp
- C++
- COBOL
- Common Lisp
- D
- Elixir
- Fortran
- FreeBASIC
- Go
- Groovy
- Haskell
- Icon
- Unicon
- J
- Java
- Julia
- Kotlin
- Lua
- M2000 Interpreter
- Mathematica
- Wolfram Language
- MATLAB
- Octave
- Nim
- Perl
- Phix
- Phixmonti
- PHP
- PicoLisp
- PowerShell
- Python
- Racket
- Raku
- RapidQ
- REXX
- Ruby
- Rust
- Scala
- Sidef
- Tcl
- UNIX Shell
- Ursa
- Visual Basic .NET
- Wren
- Yabasic
- Zkl