Environment variables: Difference between revisions
Environment variables en True BASIC |
Environment variables en Yabasic |
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PATH=\masm6;C:\;C:\CXPL;C:\UTIL;C:\DOS;C:\BORLANDC\BIN |
PATH=\masm6;C:\;C:\CXPL;C:\UTIL;C:\DOS;C:\BORLANDC\BIN |
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</pre> |
</pre> |
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=={{header|Yabasic}}== |
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<code>peek$("env","NAME")</code> Return the environment variable specified by NAME (which may be any string expression). |
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Which kind of environment variables are available on your system depends, as well as their meaning, on your system; however typing env on the command line will produce a list (for Windows and Unix alike). |
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Note, that peek$("env",...) can be written as peek$("environment",...) too. |
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=={{header|zkl}}== |
=={{header|zkl}}== |
Revision as of 19:27, 2 March 2022
![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.
- Task
Show how to get one of your process's environment variables.
The available variables vary by system; some of the common ones available on Unix include:
- PATH
- HOME
- USER
11l
<lang 11l>print(os:getenv(‘HOME’))</lang>
Ada
Print a single environment variable. <lang ada>with Ada.Environment_Variables; use Ada.Environment_Variables; with Ada.Text_Io; use Ada.Text_Io;
procedure Print_Path is begin
Put_Line("Path : " & Value("PATH"));
end Print_Path;</lang> Print all environment variable names and values. <lang ada>with Ada.Environment_Variables; use Ada.Environment_Variables; with Ada.Text_Io; use Ada.Text_Io;
procedure Env_Vars is
procedure Print_Vars(Name, Value : in String) is begin Put_Line(Name & " : " & Value); end Print_Vars;
begin
Iterate(Print_Vars'access);
end Env_Vars;</lang>
Alternative version using Matreshka
Uses Matreshka.
<lang Ada>with Ada.Wide_Wide_Text_IO;
with League.Application; with League.Strings;
procedure Main is
function "+" (Item : Wide_Wide_String) return League.Strings.Universal_String renames League.Strings.To_Universal_String;
begin
Ada.Wide_Wide_Text_IO.Put_Line (League.Application.Environment.Value (+"HOME").To_Wide_Wide_String);
end Main;</lang>
ALGOL 68
<lang algol68>print((getenv("HOME"), new line))</lang>
APL
<lang APL>
⎕ENV 'HOME' HOME /home/russtopia
</lang>
AppleScript
Invoking Finder
<lang AppleScript> tell application "Finder" to get name of home </lang>
Invoking Terminal
<lang AppleScript> "HOME : " & (do shell script "echo $HOME" & ", PATH : " & (do shell script "echo $PATH" & ", USER : " & (do shell script "echo $USER"))) </lang>
Arturo
<lang rebol>print ["path:" env\PATH] print ["user:" env\USER] print ["home:" env\HOME]</lang>
- Output:
path: /Users/drkameleon/.arturo/bin:/opt/local/bin:/opt/local/sbin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin user: drkameleon home: /Users/drkameleon
AutoHotkey
<lang autohotkey>EnvGet, OutputVar, Path MsgBox, %OutputVar%</lang>
AutoIt
<lang AutoIt>ConsoleWrite("# Environment:" & @CRLF)
Local $sEnvVar = EnvGet("LANG") ConsoleWrite("LANG : " & $sEnvVar & @CRLF)
ShowEnv("SystemDrive") ShowEnv("USERNAME")
Func ShowEnv($N)
ConsoleWrite( StringFormat("%-12s : %s\n", $N, EnvGet($N)) )
EndFunc ;==>ShowEnv</lang>
- Output:
# Environment: LANG : DE SystemDrive : C: USERNAME : HaJo
AWK
The ENVIRON array contains the values of the current environment: <lang awk>$ awk 'BEGIN{print "HOME:"ENVIRON["HOME"],"USER:"ENVIRON["USER"]}' </lang>
- Output:
HOME:/home/suchrich USER:SuchRich
Environment variables can also be assigned to awk variables before execution, with (-v) options: <lang awk>$ awk -v h=$HOME -v u=$USER 'BEGIN{print "HOME:"h,"USER:"u}' </lang>
- Output:
HOME:/home/suchrich USER:SuchRich
Listing all the environment variables: <lang awk># http://ideone.com/St5SHF BEGIN { print "# Environment:"
for (e in ENVIRON) { printf( "%10s = %s\n", e, ENVIRON[e] ) }
} END { print "# Done." } </lang>
- Output:
# Environment: AWKPATH = .:/usr/share/awk AWKLIBPATH = /usr/lib/i386-linux-gnu/gawk LANG = en_US.UTF-8 PATH = /usr/local/bin:/usr/bin:/bin HOME = /home/guest PWD = /home/guest SHLVL = 0 TMPDIR = /home/guest # Done.
BASIC
<lang qbasic>x$ = ENVIRON$("path") PRINT x$</lang>
BaCon
Case matters and needs to match <lang freebasic>PRINT GETENVIRON$("PATH")</lang>
IS-BASIC
<lang IS-BASIC>100 ASK BORDER VAR01 110 ASK DEFAULT CHANNEL VAR02 120 ASK EDITOR BUFFER VAR03 130 ASK EDITOR KEY VAR04 140 ASK EDITOR VIDEO VAR05 150 ASK FAST SAVE VAR06 160 ASK INTERRUPT KEY VAR07 170 ASK INTERRUPT NET VAR08 180 ASK INTERRUPT STOP VAR09 190 ASK KEY CLICK VAR10 200 ASK KEY DELAY VAR11 210 ASK KEY RATE VAR12 220 ASK NET CHANNEL VAR13 230 ASK NET MACHINE VAR14 240 ASK REM1 VAR15 250 ASK REM2 VAR16 260 ASK SERIAL BAUD VAR17 270 ASK SERIAL FORMAT VAR18 280 ASK STATUS VAR19 290 ASK SOUND BUFFER VAR20 300 ASK SPEAKER VAR21 310 ASK TAPE LEVEL VAR22 320 ASK TAPE SOUND VAR23 330 ASK TIMER VAR24 340 ASK VIDEO COLOR VAR25 350 ASK VIDEO MODE VAR26 360 ASK VIDEO X VAR27 370 ASK VIDEO Y VAR28</lang>
or
<lang IS-BASIC>ASK machine-option-code var</lang>
ZX Spectrum Basic
The ZX Spectrum does not use environmental variables in a traditional sense. However, it does provide a set of system variables held at a fixed memory address: <lang zxbasic>10 PRINT "The border colour is "; PEEK (23624): REM bordcr 20 PRINT "The ramtop address is "; PEEK (23730) + 256 * PEEK (23731): REM ramtop 30 POKE 23609,50: REM set keyboard pip to 50</lang>
Batch File
Batch files don't have any other kind of variables except environment variables. They can be accessed by enclosing the variable name in percent signs:
<lang dos>echo %Foo%</lang>
For interactive use one can use set
to view all environment variables or all variables starting with a certain string:
<lang dos>set
set Foo</lang>
BBC BASIC
<lang bbcbasic> PRINT FNenvironment("PATH")
PRINT FNenvironment("USERNAME") END DEF FNenvironment(envar$) LOCAL buffer%, size% SYS "GetEnvironmentVariable", envar$, 0, 0 TO size% DIM buffer% LOCAL size% SYS "GetEnvironmentVariable", envar$, buffer%, size%+1 = $$buffer%</lang>
C
<lang c>#include <stdlib.h>
- include <stdio.h>
int main() {
puts(getenv("HOME")); puts(getenv("PATH")); puts(getenv("USER")); return 0;
} </lang>
C#
<lang csharp>using System;
namespace RosettaCode {
class Program { static void Main() { string temp = Environment.GetEnvironmentVariable("TEMP"); Console.WriteLine("TEMP is " + temp); } }
}</lang>
C++
<lang cpp>#include <cstdlib>
- include <cstdio>
int main() {
puts(getenv("HOME")); return 0;
}</lang>
Clojure
<lang lisp>(System/getenv "HOME")</lang>
COBOL
<lang cobol> IDENTIFICATION DIVISION.
PROGRAM-ID. Environment-Vars.
DATA DIVISION. WORKING-STORAGE SECTION. 01 home PIC X(75).
PROCEDURE DIVISION.
- *> Method 1.
ACCEPT home FROM ENVIRONMENT "HOME" DISPLAY home
- *> Method 2.
DISPLAY "HOME" UPON ENVIRONMENT-NAME ACCEPT home FROM ENVIRONMENT-VALUE
GOBACK .</lang>
CoffeeScript
<lang coffeescript>for var_name in ['PATH', 'HOME', 'LANG', 'USER']
console.log var_name, process.env[var_name]</lang>
Common Lisp
Access to environment variables isn't a part of the Common Lisp standard, but most implementations provide some way to do it.
<lang lisp>(lispworks:environment-variable "USER")</lang>
<lang lisp>(sb-ext:posix-getenv "USER")</lang>
<lang lisp>(ccl:getenv "USER")</lang>
<lang lisp>(getenv "HOME")</lang> Ways to do this in some other implementations are listed in the Common Lisp Cookbook.
D
<lang d>import std.stdio, std.process;
void main() {
auto home = getenv("HOME");
}</lang>
<lang d>import tango.sys.Environment;
void main() {
auto home = Environment("HOME");
}</lang>
Delphi /Pascal
<lang Delphi>program EnvironmentVariable;
{$APPTYPE CONSOLE}
uses SysUtils;
begin
WriteLn('Temp = ' + GetEnvironmentVariable('TEMP'));
end.</lang>
E
<lang e><unsafe:java.lang.System>.getenv("HOME")</lang>
Eiffel
The feature get
returns the value of an environment variable. get
is defined in the library class EXECUTION_ENVIRONMENT. So the class APPLICATION inherits from EXECUTION_ENVIRONMENT in order to make get
available.
<lang eiffel >class
APPLICATION
inherit
EXECUTION_ENVIRONMENT
create
make
feature {NONE} -- Initialization
make -- Retrieve and print value for environment variable `USERNAME'. do print (get ("USERNAME")) end
end</lang>
Elixir
<lang elixir>System.get_env("PATH")</lang>
Emacs Lisp
<lang lisp>(getenv "HOME")</lang>
Erlang
<lang Erlang> os:getenv( "HOME" ). </lang>
Euphoria
<lang euphoria>puts(1,getenv("PATH"))</lang>
F#
<lang fsharp>open System
[<EntryPoint>] let main args =
printfn "%A" (Environment.GetEnvironmentVariable("PATH")) 0</lang>
Factor
<lang factor>"HOME" os-env print</lang>
Forth
<lang forth>s" HOME" getenv type</lang>
Fortran
<lang fortran>program show_home implicit none character(len=32) :: home_val ! The string value of the variable HOME integer :: home_len ! The actual length of the value integer :: stat ! The status of the value:
! 0 = ok ! 1 = variable does not exist ! -1 = variable is not long enought to hold the result
call get_environment_variable('HOME', home_val, home_len, stat) if (stat == 0) then
write(*,'(a)') 'HOME = '//trim(home_val)
else
write(*,'(a)') 'No HOME to go to!'
end if end program show_home</lang>
FreeBASIC
<lang freebasic>' FB 1.05.0 Win64
Var v = Environ("SystemRoot") Print v Sleep</lang>
- Output:
C:\WINDOWS
Frink
<lang funl>callJava["java.lang.System", "getenv", ["HOME"]]</lang>
- Output:
/home/frink
FunL
<lang funl>println( System.getenv('PATH') ) println( $home ) println( $user )</lang>
Go
- Simply
<lang go>package main
import (
"fmt" "os"
)
func main() {
fmt.Println(os.Getenv("SHELL"))
}</lang>
- Output:
/bin/bash
- Alternatively
Library function os.Environ returns all environment variables. You're on your own then to parse out the one you want. Example: <lang go>package main
import (
"fmt" "os" "strings"
)
func main() {
s := "SHELL" se := s + "=" for _, v := range os.Environ() { if strings.HasPrefix(v, se) { fmt.Println(s, "has value", v[len(se):]) return } } fmt.Println(s, "not found")
}</lang>
- Output:
SHELL has value /bin/bash
Gri
Command get env
fetches an environment variable into a synonym (a string)
<lang Gri>get env \foo HOME
show "\foo"</lang>
Quotes can be used in the usual way if the environment variable name contains spaces (which is unusual, but possible). <lang Gri>get env \foo "X Y Z"</lang>
Groovy
<lang groovy>System.getenv().each { property, value -> println "$property = $value"}</lang>
Haskell
<lang haskell>import System.Environment main = do getEnv "HOME" >>= print -- get env var
getEnvironment >>= print -- get the entire environment as a list of (key, value) pairs</lang>
hexiscript
<lang hexiscript>println env "HOME" println env "PATH" println env "USER"</lang>
HicEst
<lang HicEst>CHARACTER string*255
string = "PATH=" SYSTEM(GEteNV = string)</lang>
i
<lang i>software { print(load("$HOME")) print(load("$USER")) print(load("$PATH")) }</lang>
Icon and Unicon
<lang Icon>procedure main(arglist)
if *envars = 0 then envars := ["HOME", "TRACE", "BLKSIZE","STRSIZE","COEXPSIZE","MSTKSIZE", "IPATH","LPATH","NOERRBUF"]
every v := !sort(envars) do
write(v," = ",image(getenv(v))|"* not set *")
end</lang>
J
<lang j>2!:5'HOME'</lang>
Java
<lang java>System.getenv("HOME") // get env var System.getenv() // get the entire environment as a Map of keys to values</lang>
JavaScript
The JavaScript language has no facilities to access the computer: it relies on the host environment to provide it.
<lang javascript>var shell = new ActiveXObject("WScript.Shell"); var env = shell.Environment("PROCESS"); WScript.echo('SYSTEMROOT=' + env.item('SYSTEMROOT'));</lang>
Joy
<lang joy>"HOME" getenv.</lang>
jq
<lang jq>env.HOME</lang>If the environment variable name has spaces or special characters, the name must be given as a string, e.g. env."HOME".
jsish
The Jsi Util module provides access to set Util.setenv(name, value) and get Util.getenv(name) process environment variables. Util.getenv(), with no argument will return an object with all available name:value pairs. <lang javascript>/* Environment variables, in Jsi */ puts(Util.getenv("HOME")); var environment = Util.getenv(); puts(environment.PATH);</lang>
Julia
<lang julia>@show ENV["PATH"] @show ENV["HOME"] @show ENV["USER"]</lang>
K
<lang K>_getenv "HOME"</lang>
Kotlin
<lang scala>// version 1.0.6
// tested on Windows 10
fun main(args: Array<String>) {
println(System.getenv("SystemRoot"))
}</lang>
- Output:
C:\WINDOWS
langur
<lang langur>writeln "HOME: ", _env["HOME"] writeln "PATH: ", _env["PATH"] writeln "USER: ", _env["USER"]</lang>
We could also the short-hand form of indexing by string. This is limited to code points used for tokens and does not allow for spaces, nor an index alternate. <lang langur>writeln "HOME: ", _env'HOME writeln "PATH: ", _env'PATH writeln "USER: ", _env'USER</lang>
Lasso
<lang Lasso>#!/usr/bin/lasso9
define getenv(sysvar::string) => { local(regexp = regexp( -find = `(?m)^` + #sysvar + `=(.*?)$`, -input = sys_environ -> join('\n'), -ignorecase )) return #regexp ->find ? #regexp -> matchString(1) }
stdoutnl(getenv('HOME')) stdoutnl(getenv('PATH')) stdoutnl(getenv('USER')) stdoutnl(getenv('WHAT'))</lang>
- Output:
/Users/rosetta /opt/local/bin:/opt/local/sbin:/usr/local/bin/:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/opt/X11/bin rosetta
Liberty BASIC
Built-in variables
<lang lb>print StartupDir$ print DefaultDir$</lang>
Other variables
<lang lb>print GetEnvironmentVariable$("USERNAME")
print GetEnvironmentVariable$("USERPROFILE") ' equivalent to UNIX HOME variable print GetEnvironmentVariable$("PATH") end
function GetEnvironmentVariable$(lpName$)
'get the value of an environment variable nSize = 1024
[Retry]
lpBuffer$ = space$(nSize)
calldll #kernel32, "GetEnvironmentVariableA", _ lpName$ as ptr, _ lpBuffer$ as ptr, _ nSize as ulong, _ result as ulong
select case ' buffer too small case result > nSize nSize = result goto [Retry]
' variable found case result > 0 GetEnvironmentVariable$ = left$(lpBuffer$, result) end select
end function</lang>
LIL
LIL does not ship with a command to retrieve process environment variables. The system command could be used, but here is an extension in C for the lil shell.
<lang c> static LILCALLBACK lil_value_t fnc_env(lil_t lil, size_t argc, lil_value_t* argv) {
if (!argc) return NULL; return lil_alloc_string(getenv(lil_to_string(argv[0])));
}</lang>
Then inside the main functions for repl and nonint (Interactive, Noninteractive): <lang c>lil_register(lil, "env", fnc_env);</lang>
Now lil can get at the environment. That could fairly easily be extended further to return the entire environment array if no arguments are passed to env, this just returns an empty result for that case. Defaults values could also be supported if the named environment variable is empty. Etcetera. Setting variables would be similar, a few lines of lil C to wrap a call to libc setenv in a new command, and registering the command.
- Output:
prompt$ make cc -c -g3 -std=c99 -pedantic -Wall -Wextra -Wno-format -Wno-long-long -Wno-unused-parameter main.c -o main.o cc -g -L. -o lil main.o -llil -lm prompt$ lil Little Interpreted Language Interactive Shell # env TERM xterm-256color
Lingo
<lang lingo>sx = xtra("Shell").new() if the platform contains "win" then
path = sx.shell_cmd("echo %PATH%").line[1]
else
path = sx.shell_cmd("echo $PATH").line[1]
end if</lang>
Logtalk
Using the standard library: <lang logtalk>os::environment_variable('PATH', Path).</lang>
LSL
Rez a box on the ground, and add the following as a New Script. <lang LSL>default { state_entry() { llOwnerSay("llGetTimestamp()="+(string)llGetTimestamp()); llOwnerSay("llGetEnergy()="+(string)llGetEnergy()); llOwnerSay("llGetFreeMemory()="+(string)llGetFreeMemory()); llOwnerSay("llGetMemoryLimit()="+(string)llGetMemoryLimit()); } }</lang>
- Output:
llGetTimestamp()=2012-07-18T01:26:12.133137Z llGetEnergy()=1.230000 llGetFreeMemory()=16000 llGetMemoryLimit()=65536
Lua
<lang lua>print( os.getenv( "PATH" ) )</lang>
M2000 Interpreter
<lang M2000 Interpreter> Module CheckIt {
\\ using read only variablles Print "Platform: ";Platform$ Print "Computer Os: "; Os$ Print "Type of OS: ";OsBit;" bit" Print "Computer Name:"; Computer$ Print "User Name: "; User.Name$ \\ using WScript.Shell Declare objShell "WScript.Shell" With objShell, "Environment" set env ("Process") With env, "item" as Env$() Print Env$("PATH") Print Env$("HOMEPATH") Declare objShell Nothing \\ using internal Information object Declare OsInfo INFORMATION With OsInfo, "build" as build, "NtDllVersion" as NtDllVersion$ Method OsInfo, "GetCurrentProcessSID" as PID$ Method OsInfo, "IsProcessElevated" as isElevated Print "Os build number: ";build Print "Nr Dll version: ";NtDllVersion$ Print "ProcessSID: ";pid$ Print "Is Process Eleveted: ";isElevated Declare OsInfo Nothing
} Checkit </lang>
Make
Make variables are initialized from the environment, so simply <lang Make>TARGET = $(HOME)/some/thing.txt foo: echo $(TARGET)</lang>
The shell code in a rule can use the shell's environment in the usual way (Unix Shell), but remember $
must be doubled $$
to get a literal $
in that code.
<lang Make>bar:
echo "$$HOME"</lang>
If you mistakenly write just $HOME
then it means the makefile $H
followed by characters OME
.
<lang Make>H = oops ... bar: echo $HOME
- prints oops ... OME</lang>
Maple
<lang Maple>getenv("PATH");</lang>
Mathematica / Wolfram Language
<lang Mathematica>Environment["PATH"]</lang>
MATLAB / Octave
<lang MATLAB> getenv('HOME')
getenv('PATH') getenv('USER')</lang>
Mercury
<lang mercury>:- module env_var.
- - interface.
- - import_module io.
- - pred main(io::di, io::uo) is det.
- - implementation.
- - import_module maybe, string.
main(!IO) :-
io.get_environment_var("HOME", MaybeValue, !IO), ( MaybeValue = yes(Value), io.write_string("HOME is " ++ Value ++ "\n", !IO) ; MaybeValue = no, io.write_string("environment variable HOME not set\n", !IO) ).</lang>
min
<lang min>$PATH</lang>
Modula-3
<lang modula3>MODULE EnvVars EXPORTS Main;
IMPORT IO, Env;
VAR
k, v: TEXT;
BEGIN
IO.Put(Env.Get("HOME") & "\n");
FOR i := 0 TO Env.Count - 1 DO Env.GetNth(i, k, v); IO.Put(k & " = " & v & "\n") END
END EnvVars.</lang>
MUMPS
ANSI MUMPS doesn't allow access to the operating system except possibly through the View command and $View function, both of which are implementation specific. Intersystems' Caché does allow you to create processes with the $ZF function, and if the permissions for the Caché process allow it you can perform operating system commands.
In Caché on OpenVMS in an FILES-11 filesystem ODS-5 mode these could work: <lang MUMPS> Set X=$ZF(-1,"show logical")
Set X=$ZF(-1,"show symbol")</lang>
NetRexx
When NetRexx runs under a JVM, system ENVIRONMENT variables are complimented by JVM system properties. This sample shows how to get both. <lang NetRexx>/* NetRexx */ options replace format comments java crossref symbols nobinary
runSample(arg) return
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ method sysEnvironment(vn = ) public static
if vn.length > 0 then do envName = vn envValu = System.getenv(envName) if envValu = null then envValu = say envName '=' envValu end else do envVars = System.getenv() key = String loop key over envVars.keySet() envName = key envValu = String envVars.get(key) say envName '=' envValu end key end return
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ method sysProperties(vn = ) public static
if vn.length > 0 then do propName = vn propValu = System.getProperty(propName) if propValu = null then propValu = say propName '=' propValu end else do sysProps = System.getProperties() key = String loop key over sysProps.keySet() propName = key propValu = sysProps.getProperty(key) say propName '=' propValu end key end return
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ method runSample(arg) public static
parse arg ev pv . if ev = then ev = 'CLASSPATH' if pv = then pv = 'java.class.path' say '-'.left(80, '-').overlay(' Environment "'ev'" ', 5) sysEnvironment(ev) say '-'.left(80, '-').overlay(' Properties "'pv'" ', 5) sysProperties(pv) say say '-'.left(80, '-').overlay(' Environment ', 5) sysEnvironment() say '-'.left(80, '-').overlay(' Properties ', 5) sysProperties() say return
</lang>
- Output:
---- Environment "CLASSPATH" --------------------------------------------------- CLASSPATH = /usr/local/NetRexx/runlib/NetRexxR.jar:. ---- Properties "java.class.path" ---------------------------------------------- java.class.path = /usr/local/NetRexx/runlib/NetRexxR.jar:. ---- Environment --------------------------------------------------------------- HOME = /Users/nrxuser HISTCONTROL = ignoredups USER = nrxuser ZBASHRC = 1 COMMAND_MODE = unix2003 CLASSPATH = /usr/local/NetRexx/runlib/NetRexxR.jar:. SHELL = /bin/bash . . . ---- Properties ---------------------------------------------------------------- java.vm.specification.name = Java Virtual Machine Specification sun.cpu.endian = little sun.io.unicode.encoding = UnicodeBig sun.os.patch.level = unknown file.separator = / java.vendor = Oracle Corporation sun.java.launcher = SUN_STANDARD java.specification.vendor = Oracle Corporation user.home = /Users/nrxuser java.class.path = /usr/local/NetRexx/runlib/NetRexxR.jar:. java.vm.vendor = Oracle Corporation java.runtime.name = Java(TM) SE Runtime Environment . . .
NewLISP
<lang NewLISP>> (env "SHELL") "/bin/zsh" > (env "TERM") "xterm"</lang>
Nim
<lang nim>import os echo getEnv("HOME")</lang>
NSIS
While common environment variables exist as constants within the NSIS script compilation environment (see NSIS documentation), arbitrarily-named environment variables' values may be retrieved using ExpandEnvStrings. <lang nsis>ExpandEnvStrings $0 "%PATH%" ; Retrieve PATH and place it in builtin register 0. ExpandEnvStrings $1 "%USERPROFILE%" ; Retrieve the user's profile location and place it in builtin register 1. ExpandEnvStrings $2 "%USERNAME%" ; Retrieve the user's account name and place it in builtin register 2.</lang>
Objective-C
[[NSProcessInfo processInfo] environment]
returns an NSDictionary of the current environment.
<lang objc>[[[NSProcessInfo processInfo] environment] objectForKey:@"HOME"]</lang>
OCaml
<lang ocaml>Sys.getenv "HOME"</lang>
Oforth
<lang Oforth>System getEnv("PATH") println</lang>
Oz
<lang oz>{System.showInfo "This is where Mozart is installed: "#{OS.getEnv 'OZHOME'}}</lang>
PARI/GP
<lang parigp>getenv("HOME")</lang>
<lang parigp>externstr("echo $HOME")</lang>
In older versions, the command must effectively be triple-quoted: <lang parigp>extern("echo \"\\\"$HOME\\\"\"")</lang> The shell sees <lang bash>echo "\"$HOME\""</lang> which causes it to return
"/home/username"
so that the result is interpreted by GP as a string.
Leaving out the quotation marks allows external commands to return expressions that are then evaluated by GP. For example, <lang parigp>extern("echo Pi")</lang> causes the shell to send Pi back to GP, which interprets the result and returns
%1 = 3.141592653589793238462643383
Perl
The %ENV
hash maps environment variables to their values:
<lang perl>print $ENV{HOME}, "\n";</lang>
The POSIX
module also has getenv()
which is the same thing as a function.
<lang perl>use POSIX 'getenv';
print getenv("HOME"),"\n";</lang>
Phix
without js -- none such in a browser, that I know of ?getenv("PATH")
PHP
The $_ENV associative array maps environmental variable names to their values: <lang php>$_ENV['HOME']</lang>
PicoLisp
<lang PicoLisp>: (sys "TERM") -> "xterm"
- (sys "SHELL")
-> "/bin/bash"</lang>
Pike
<lang Pike>write("%s\n", getenv("SHELL"));</lang>
- Output:
/bin/bash
PowerShell
Environment variables can be found in the Env: drive and are accessed using a special variable syntax: <lang powershell>$Env:Path</lang> To get a complete listing of all environment variables one can simply query the appropriate drive for its contents: <lang powershell>Get-ChildItem Env:</lang>
Prolog
SWI-Prolog has the built in function getenv.
?- getenv('TEMP', Temp).
PureBasic
PureBasic has the built in funtion <lang PureBasic>GetEnvironmentVariable("Name")</lang> Example <lang PureBasic>If OpenConsole()
PrintN("Path:"+#CRLF$ + GetEnvironmentVariable("PATH")) PrintN(#CRLF$+#CRLF$+"NUMBER_OF_PROCESSORS= "+ GetEnvironmentVariable("NUMBER_OF_PROCESSORS"))
PrintN(#CRLF$+#CRLF$+"Press Enter to quit.") Input() CloseConsole()
EndIf</lang>
Python
The os.environ dictionary maps environmental variable names to their values: <lang python>import os os.environ['HOME']</lang>
R
<lang R>Sys.getenv("PATH")</lang>
Racket
<lang racket>
- lang racket
(getenv "HOME") </lang>
Raku
(formerly Perl 6)
The %*ENV
hash maps environment variables to their values:
<lang perl6>say %*ENV<HOME>;</lang>
REBOL
<lang REBOL>print get-env "HOME"</lang>
Retro
<lang Retro>here "HOME" getEnv here puts</lang>
REXX
Each REXX interpreter sets its own rules by what identifies the pool in which the environmental variables are named. In addition, each operation system (OS) has their own definition as well. This makes it problematic in the accessing/acquiring of environmental variables. Most programmers know what REXX interpreter they are using, and furthermore, they also know what operating system they are writing the REXX program for, so most programmers hard-wire (explicitly code) the "access-name" of the system environmental variables into the program.
The following will work for
- Regina
- R4
- ROO
for the DOS shell under Microsoft Windows (any version).
(Also successfully tested with Regina under the bash shell in UNIX.)
<lang rexx>/*REXX program shows how to get an environmental variable under Windows*/
x=value('TEMP',,'SYSTEM')</lang> The following will work for
- PC/REXX
- Personal REXX
- Regina
- Open Object Rexx
for the DOS shell under Microsoft Windows (any version).
(Also successfully tested with Regina and ooRexx under the bash shell in UNIX.)
<lang rexx>/*REXX program shows how to get an environmental variable under Windows*/
x=value('TEMP',,'ENVIRONMENT')</lang>
The brexx interpreter provides a getenv function for accessing environment variables:
<lang rexx>x=getenv("PATH") /* Get the contents of the path environment variable */</lang>
Other REXX interpreters have their own requirements to identify the SYSTEM environment.
VM/CMS has something called GLOBALV (global variables) and are of three types:
- temporary, lasting only for execution of the REXX program
- temporary, lasting only for LOGON or CMS session)
- permanent
As such, CMS has its own command interface for these variables.
Ring
<lang ring> see get("path") </lang>
Ruby
The ENV hash maps environment variable names to their values: <lang ruby>ENV['HOME']</lang>
Run BASIC
<lang runbasic>' ------- Major environment variables ------------------------------------------- 'DefaultDir$ - The folder path where program files are read/written by default 'Platform$ - The operating system on which Run BASIC is being hosted 'UserInfo$ - This is information about the user's web browser 'UrlKeys$ - Contains informational parameters from the URL submitted when the user connected 'UserAddress$ - Contains the IP address of the user 'ProjectsRoot$ - The folder path where Run BASIC keeps programming projects 'ResourcesRoot$ - The folder path where Run BASIC keeps web-servable files 'Err$ - A description of the last runtime error 'Err - A numeric code for the last runtime error (errors that have no code use zero) 'EventKey$ - The id of the object that generated the last user event 'RowIndex - The numeric index of the table or database accessor link that generated the last user event
print "User Info is : ";UserInfo$
print "Platform is : ";Platform$
print "Url Keys is : ";UrlKeys$
print "User Address is: ";UserAddress$
print "Event Key is : ";EventKey$
print "Default Dir is : ";DefaultDir$</lang>
{{out}} User Info is : Mozilla/5.0 (Windows NT 6.1) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.79 Safari/535.11 Platform is : win32 Url Keys is : none User Address is: 127.0.0.1 Event Key is : none Default Dir is : c:\rbp101
Rust
<lang Rust>use std::env;
fn main() {
println!("{:?}", env::var("HOME")); println!(); for (k, v) in env::vars().filter(|(k, _)| k.starts_with('P')) { println!("{}: {}", k, v); }
} </lang>
- Output:
Ok("/root") PATH: /root/.cargo/bin:/root/.cargo/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin PLAYGROUND_EDITION: 2018 PLAYGROUND_TIMEOUT: 10 PWD: /playground
Note that var_os
and vars_os
are also available, which produce OsString
instead of String
, offering compatibility with non-utf8 systems.
Scala
<lang scala>sys.env.get("HOME")</lang>
Seed7
Seed7 provides the function getenv, to get the value of an environment variable. Environment variables are highly operating system dependent. Some variables such as HOME are not always defined and others like PATH use an operating system dependent format (different delimiters). Seed7 provides the functions homeDir and getSearchPath to get the home directory and the search path in an operating system independent manner.
<lang seed7>$ include "seed7_05.s7i";
const proc: main is func
begin writeln(getenv("HOME")); end func;</lang>
Sidef
The ENV hash maps environment variables to their values: <lang ruby>say ENV{'HOME'};</lang>
Slate
<lang slate>Environment variables at: 'PATH'.
"==> '/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games'"</lang>
Smalltalk
Use the OSProcess library to gain access to environment variables:
<lang smalltalk> OSProcess thisOSProcess environment at: #HOME. OSProcess thisOSProcess environment at: #PATH. OSProcess thisOSProcess environment at: #USER. </lang>
SNOBOL4
The host(4) function returns a known environment variable. <lang SNOBOL4> output = host(4,'PATH') end</lang>
Standard ML
<lang sml>OS.Process.getEnv "HOME"</lang> returns an option type which is either SOME value or NONE if variable doesn't exist
Stata
Use the env extended macro function.
<lang stata>display "`:env PATH'" display "`:env USERNAME'" display "`:env USERPROFILE'"</lang>
Swift
<lang swift>print("USER: \(ProcessInfo.processInfo.environment["USER"] ?? "Not set")") print("PATH: \(ProcessInfo.processInfo.environment["PATH"] ?? "Not set")")</lang>
True BASIC
<lang qbasic>ASK #1: ACCESS type$ ASK BACK red ASK COLOR red ASK COLOR MIX (2) red, green, blue ASK CURSOR vble1, vble2 ASK #2: DATUM type$ ASK DIRECTORY dir$ ASK #3: ERASABLE type$ ASK #4: FILESIZE vble09 ASK #5: FILETYPE vble10 ASK FREE MEMORY vble11 ASK #61: MARGIN vble12 ASK MAX COLOR vble13 ASK MAX CURSOR vble1, vble2 ASK MODE vble15$ ASK NAME vble16$ ASK #7: ORGANIZATION vble17$ ASK PIXELS vble1, vble2 ASK #8: POINTER vble19$ ASK #9: RECORD vble20 ASK #1: RECSIZE vble21 ASK #2: RECTYPE vble22$ ASK SCREEN vble1, vble2, vble3, vble4 ASK #3: SETTER vble24$ ASK TEXT JUSTIFY vble1$, vble2$ ASK WINDOW vble1, vble2, vble3, vble4 ASK #4: ZONEWIDTH vble27</lang>
Tcl
The env
global array maps environmental variable names to their values:
<lang tcl>$env(HOME)</lang>
TXR
TXR can treat the environment vector as text stream:
<lang txr>@(next :env)
@(collect)
@VAR=@VAL
@(end)</lang>
A recently added gather
directive is useful for extracting multiple items of data from an unordered stream of this kind (not only the environment vector):
<lang txr>@(next :env)
@(gather)
HOME=@home
USER=@user
PATH=@path
@(end)</lang>
What if some of the variables might not exist? Gather has some discipline for that. The following means that three variables are required (the gather construct fails if they are not found), but shell
is optional with a default value of /bin/sh
if it is not extracted from the data:
<lang txr>@(next :env)
@(gather :vars (home user path (shell "/bin/sh")))
HOME=@home
USER=@user
PATH=@path
SHELL=@shell
@(end)</lang>
From TXR Lisp, the environment is available via the (env)
function, which returns a raw list of "name=value
strings. The (env-hash)
function returns a hash from environment keys to their values.
<lang bash>$ ./txr -p "(mapcar (env-hash) '(\"HOME\" \"USER\" \"PATH\"))" ("/home/kaz" "kaz" "/home/kaz/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/home/kaz/bin"</lang>
Here, the hash is being used as a function to filter several environment keys to their values via mapcar
.
Platform note: On POSIX, environment variables, which are extracted using extern char **environ
are assumed to contain UTF-8. On Windows, the GetEnvironmentStringsW
function is used to obtain the environment vector as wide character data.
UNIX Shell
In the Unix Shell Language, environment variables are available as ordinary variables:
<lang bash>echo "$HOME"</lang>
An ordinary variable can be marked as an environment variable with the export
command:
<lang bash>export VAR</lang>
Now child processes launched by the shell will have an environment variable called VAR
.
The Unix command "env" will print out all of the environment variables as key=value pairs on standard output.
Ursa
<lang ursa>import "system" out (system.getenv "HOME") endl console</lang>
Ursala
The argument to the main program is a record initialized by the run-time system in which one of the fields (environs) contains the environment as a list of key:value pairs. <lang Ursala>#import std
- executable ('parameterized',)
showenv = <.file$[contents: --<>]>+ %smP+ ~&n-={'TERM','SHELL','X11BROWSER'}*~+ ~environs</lang> The rest of this application searches for the three variables named and displays them on standard output.
- Here is a bash session:
$ showenv < 'TERM': 'Eterm', 'SHELL': '/bin/bash', 'X11BROWSER': '/usr/bin/firefox'>
Vlang
<lang vlang>// Environment variables in V // v run environment_variables.v module main
import os
pub fn main() {
print('In the $os.environ().len environment variables, ') println('\$HOME is set to ${os.getenv('HOME')}')
}</lang>
- Output:
prompt$ v run environment-variables.v In the 64 environment variables, $HOME is set to /home/btiffin
Vedit macro language
<lang vedit>Get_Environment(10,"PATH") Message(@10)</lang> Or with short keywords: <lang vedit>GE(10,"PATH") M(@10)</lang>
Visual Basic
<lang vb>Debug.Print Environ$("PATH")</lang>
Wren
Wren CLI doesn't currently expose a way to obtain the value of an environment variable.
However, if Wren is embedded in (say) a suitable Go program, then we can ask the latter to obtain it for us. <lang ecmascript>/* environment_variables.wren */ class Environ {
foreign static variable(name)
}
System.print(Environ.variable("SHELL"))</lang>
which we embed in the following Go program and run it.
<lang go>/* environment_variables.go */ package main
import (
wren "github.com/crazyinfin8/WrenGo" "os"
)
type any = interface{}
func getEnvironVariable(vm *wren.VM, parameters []any) (any, error) {
name := parameters[1].(string) return os.Getenv(name), nil
}
func main() {
vm := wren.NewVM() fileName := "environment_variables.wren" methodMap := wren.MethodMap{"static variable(_)": getEnvironVariable} classMap := wren.ClassMap{"Environ": wren.NewClass(nil, nil, methodMap)} module := wren.NewModule(classMap) vm.SetModule(fileName, module) vm.InterpretFile(fileName) vm.Free()
}</lang>
- Output:
/bin/bash
XPL0
This task was particularly worthwhile because it revealed a discrepancy in the way 32-bit XPL0 accessed the environment block. A small mod to Tran's PMODE.ASM DPMI was required to make the 32-bit protected-mode version work the same as the 16-bit real-mode versions.
<lang XPL0>include c:\cxpl\codes; \intrinsic 'code' declarations string 0; \use zero-terminated strings int CpuReg, PspSeg, EnvSeg, I, J, C; char EnvVar; [CpuReg:= GetReg; \access CPU registers PspSeg:= CpuReg(9); \get segment address of our PSP EnvSeg:= Peek(PspSeg,$2C) + Peek(PspSeg,$2D)<<8; EnvVar:= "PATH"; \environment variable I:= 0; loop [J:= 0;
loop [C:= Peek(EnvSeg,I); I:= I+1; if C = 0 then quit; if C = EnvVar(J) then [J:= J+1; if J = 4 then [Text(0, EnvVar); \show env. var. loop [C:= Peek(EnvSeg,I); \ and rest of I:= I+1; \ its string if C = 0 then exit; ChOut(0, C); ]; ]; ] else J:= 5; \line must start with environment variable ]; if Peek(EnvSeg,I) = 0 then quit; \double 0 = env. var. not found ];
]</lang>
- Output:
PATH=\masm6;C:\;C:\CXPL;C:\UTIL;C:\DOS;C:\BORLANDC\BIN
Yabasic
peek$("env","NAME")
Return the environment variable specified by NAME (which may be any string expression).
Which kind of environment variables are available on your system depends, as well as their meaning, on your system; however typing env on the command line will produce a list (for Windows and Unix alike).
Note, that peek$("env",...) can be written as peek$("environment",...) too.
zkl
<lang zkl>System.getenv("HOME") /home/craigd System.getenv() //--> Dictionary of all env vars</lang>
- Programming Tasks
- Programming environment operations
- Environment variables
- Initialization
- Simple
- M4/Omit
- TI-83 BASIC/Omit
- TI-89 BASIC/Omit
- Unlambda/Omit
- 11l
- Ada
- ALGOL 68
- APL
- AppleScript
- Arturo
- AutoHotkey
- AutoIt
- AWK
- BASIC
- BaCon
- IS-BASIC
- ZX Spectrum Basic
- Batch File
- BBC BASIC
- C
- C sharp
- C++
- Clojure
- COBOL
- CoffeeScript
- Common Lisp
- D
- Phobos
- Tango
- Delphi
- Pascal
- E
- Eiffel
- Elixir
- Emacs Lisp
- Erlang
- Euphoria
- F Sharp
- Factor
- Forth
- Fortran
- FreeBASIC
- Frink
- FunL
- Go
- Gri
- Groovy
- Haskell
- Hexiscript
- HicEst
- I
- Icon
- Unicon
- J
- Java
- JavaScript
- Joy
- Jq
- Jsish
- Julia
- K
- Kotlin
- Langur
- Lasso
- Liberty BASIC
- LIL
- Lingo
- Shell Xtra
- Logtalk
- LSL
- Lua
- M2000 Interpreter
- Make
- Maple
- Mathematica
- Wolfram Language
- MATLAB
- Octave
- Mercury
- Min
- Modula-3
- MUMPS
- NetRexx
- NewLISP
- Nim
- NSIS
- Objective-C
- OCaml
- Oforth
- Oz
- PARI/GP
- Perl
- Phix
- PHP
- PicoLisp
- Pike
- PowerShell
- Prolog
- PureBasic
- Python
- R
- Racket
- Raku
- REBOL
- Retro
- REXX
- Ring
- Ruby
- Run BASIC
- Rust
- Scala
- Seed7
- Sidef
- Slate
- Smalltalk
- SNOBOL4
- Standard ML
- Stata
- Swift
- True BASIC
- Tcl
- TXR
- UNIX Shell
- Ursa
- Ursala
- Vlang
- Vedit macro language
- Visual Basic
- Wren
- WrenGo
- XPL0
- Yabasic
- Zkl