Environment variables: Difference between revisions
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<syntaxhighlight lang="is-basic">ASK machine-option-code var</syntaxhighlight>
==={{header|SmallBASIC}}===
print env("HOME")
print env("PATH")
print env("USER")
</syntaxhighlight>
==={{header|ZX Spectrum Basic}}===
Line 578 ⟶ 585:
=={{header|langur}}==
<syntaxhighlight lang="langur">
writeln "
▲<syntaxhighlight lang="langur">writeln "HOME: ", _env'HOME
writeln "PATH: ", _env'PATH
writeln "USER: ", _env'USER
</syntaxhighlight>
=={{header|Lasso}}==
|
Latest revision as of 13:50, 21 June 2024
![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
print(os:getenv(‘HOME’))
Ada
Print a single environment variable.
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;
Print all environment variable names and values.
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;
Alternative version using Matreshka
Uses Matreshka.
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;
ALGOL 68
print((getenv("HOME"), new line))
APL
⎕ENV 'HOME'
HOME /home/russtopia
AppleScript
Invoking Finder
tell application "Finder" to get name of home
Invoking Terminal
"HOME : " & (do shell script "echo $HOME" & ", PATH : " & (do shell script "echo $PATH" & ", USER : " & (do shell script "echo $USER")))
Arturo
print ["path:" env\PATH]
print ["user:" env\USER]
print ["home:" env\HOME]
- 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
EnvGet, OutputVar, Path
MsgBox, %OutputVar%
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
- Output:
# Environment: LANG : DE SystemDrive : C: USERNAME : HaJo
AWK
The ENVIRON array contains the values of the current environment:
$ awk 'BEGIN{print "HOME:"ENVIRON["HOME"],"USER:"ENVIRON["USER"]}'
- Output:
HOME:/home/suchrich USER:SuchRich
Environment variables can also be assigned to awk variables before execution, with (-v) options:
$ awk -v h=$HOME -v u=$USER 'BEGIN{print "HOME:"h,"USER:"u}'
- Output:
HOME:/home/suchrich USER:SuchRich
Listing all the environment variables:
# http://ideone.com/St5SHF
BEGIN { print "# Environment:"
for (e in ENVIRON) { printf( "%10s = %s\n", e, ENVIRON[e] ) }
}
END { print "# Done." }
- 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
x$ = ENVIRON$("path")
PRINT x$
BaCon
Case matters and needs to match
PRINT GETENVIRON$("PATH")
IS-BASIC
100 ASK BORDER VAR01
110 ASK DEFAULT CHANNEL VAR02
120 ASK EDITOR BUFFER VAR03
130 ASK EDITOR KEY VAR04
140 ASK EDITOR VIDEO VAR05
150 ASK FAST SAVE VAR06
160 ASK INTERRUPT KEY VAR07
170 ASK INTERRUPT NET VAR08
180 ASK INTERRUPT STOP VAR09
190 ASK KEY CLICK VAR10
200 ASK KEY DELAY VAR11
210 ASK KEY RATE VAR12
220 ASK NET CHANNEL VAR13
230 ASK NET MACHINE VAR14
240 ASK REM1 VAR15
250 ASK REM2 VAR16
260 ASK SERIAL BAUD VAR17
270 ASK SERIAL FORMAT VAR18
280 ASK STATUS VAR19
290 ASK SOUND BUFFER VAR20
300 ASK SPEAKER VAR21
310 ASK TAPE LEVEL VAR22
320 ASK TAPE SOUND VAR23
330 ASK TIMER VAR24
340 ASK VIDEO COLOR VAR25
350 ASK VIDEO MODE VAR26
360 ASK VIDEO X VAR27
370 ASK VIDEO Y VAR28
or
ASK machine-option-code var
SmallBASIC
print env("HOME")
print env("PATH")
print env("USER")
ZX Spectrum Basic
The ZX Spectrum does not use environmental variables in a traditional sense. However, it does provide a set of system variables held at a fixed memory address:
10 PRINT "The border colour is "; PEEK (23624): REM bordcr
20 PRINT "The ramtop address is "; PEEK (23730) + 256 * PEEK (23731): REM ramtop
30 POKE 23609,50: REM set keyboard pip to 50
Batch File
Batch files don't have any other kind of variables except environment variables. They can be accessed by enclosing the variable name in percent signs:
echo %Foo%
For interactive use one can use set
to view all environment variables or all variables starting with a certain string:
set
set Foo
BBC BASIC
PRINT FNenvironment("PATH")
PRINT FNenvironment("USERNAME")
END
DEF FNenvironment(envar$)
LOCAL buffer%, size%
SYS "GetEnvironmentVariable", envar$, 0, 0 TO size%
DIM buffer% LOCAL size%
SYS "GetEnvironmentVariable", envar$, buffer%, size%+1
= $$buffer%
C
#include <stdlib.h>
#include <stdio.h>
int main() {
puts(getenv("HOME"));
puts(getenv("PATH"));
puts(getenv("USER"));
return 0;
}
C#
using System;
namespace RosettaCode {
class Program {
static void Main() {
string temp = Environment.GetEnvironmentVariable("TEMP");
Console.WriteLine("TEMP is " + temp);
}
}
}
C++
#include <cstdlib>
#include <cstdio>
int main()
{
puts(getenv("HOME"));
return 0;
}
Clojure
(System/getenv "HOME")
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
.
CoffeeScript
for var_name in ['PATH', 'HOME', 'LANG', 'USER']
console.log var_name, process.env[var_name]
Common Lisp
Access to environment variables isn't a part of the Common Lisp standard, but most implementations provide some way to do it.
(lispworks:environment-variable "USER")
(sb-ext:posix-getenv "USER")
(ccl:getenv "USER")
(getenv "HOME")
Ways to do this in some other implementations are listed in the Common Lisp Cookbook.
D
import std.stdio, std.process;
void main() {
auto home = getenv("HOME");
}
import tango.sys.Environment;
void main() {
auto home = Environment("HOME");
}
Delphi /Pascal
program EnvironmentVariable;
{$APPTYPE CONSOLE}
uses SysUtils;
begin
WriteLn('Temp = ' + GetEnvironmentVariable('TEMP'));
end.
E
<unsafe:java.lang.System>.getenv("HOME")
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.
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
Elixir
System.get_env("PATH")
Emacs Lisp
(getenv "HOME")
EMal
fun showVariable = <text variable|writeLine(variable + ": '" + Runtime.get(variable) + "'")
showVariable("SystemDrive")
showVariable("USERNAME")
# we can get the environment variables as a map
Map variables = Runtime.variables()
writeLine(variables["TEMP"])
- Output:
SystemDrive: 'C:' USERNAME: 'XXXYYY' C:\Users\xxxyyy\AppData\Local\Temp
Erlang
os:getenv( "HOME" ).
Euphoria
puts(1,getenv("PATH"))
F#
open System
[<EntryPoint>]
let main args =
printfn "%A" (Environment.GetEnvironmentVariable("PATH"))
0
Factor
"HOME" os-env print
Forth
s" HOME" getenv type
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
FreeBASIC
' FB 1.05.0 Win64
Var v = Environ("SystemRoot")
Print v
Sleep
- Output:
C:\WINDOWS
Frink
callJava["java.lang.System", "getenv", ["HOME"]]
- Output:
/home/frink
FunL
println( System.getenv('PATH') )
println( $home )
println( $user )
FutureBasic
include "NSLog.incl"
NSLog(@"%@",fn NSUserName)
NSLog(@"%@",fn NSFullUserName)
NSLog(@"%@",fn NSHomeDirectory)
NSLog(@"%@",fn NSTemporaryDirectory)
HandleEvents
Go
- Simply
package main
import (
"fmt"
"os"
)
func main() {
fmt.Println(os.Getenv("SHELL"))
}
- 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:
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")
}
- Output:
SHELL has value /bin/bash
Gri
Command get env
fetches an environment variable into a synonym (a string)
get env \foo HOME
show "\foo"
Quotes can be used in the usual way if the environment variable name contains spaces (which is unusual, but possible).
get env \foo "X Y Z"
Groovy
System.getenv().each { property, value -> println "$property = $value"}
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
hexiscript
println env "HOME"
println env "PATH"
println env "USER"
HicEst
CHARACTER string*255
string = "PATH="
SYSTEM(GEteNV = string)
i
software {
print(load("$HOME"))
print(load("$USER"))
print(load("$PATH"))
}
Icon and Unicon
J
2!:5'HOME'
Java
System.getenv("HOME") // get env var
System.getenv() // get the entire environment as a Map of keys to values
JavaScript
The JavaScript language has no facilities to access the computer: it relies on the host environment to provide it.
var shell = new ActiveXObject("WScript.Shell");
var env = shell.Environment("PROCESS");
WScript.echo('SYSTEMROOT=' + env.item('SYSTEMROOT'));
Joy
"HOME" getenv.
jq
env.HOME
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.
/* Environment variables, in Jsi */
puts(Util.getenv("HOME"));
var environment = Util.getenv();
puts(environment.PATH);
Julia
@show ENV["PATH"]
@show ENV["HOME"]
@show ENV["USER"]
K
_getenv "HOME"
Kotlin
// version 1.0.6
// tested on Windows 10
fun main(args: Array<String>) {
println(System.getenv("SystemRoot"))
}
- Output:
C:\WINDOWS
langur
writeln "HOME: ", _env'HOME
writeln "PATH: ", _env'PATH
writeln "USER: ", _env'USER
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'))
- 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
print StartupDir$
print DefaultDir$
Other variables
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
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.
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])));
}
Then inside the main functions for repl and nonint (Interactive, Noninteractive):
lil_register(lil, "env", fnc_env);
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
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
Logtalk
Using the standard library:
os::environment_variable('PATH', Path).
LSL
Rez a box on the ground, and add the following as a New Script.
default {
state_entry() {
llOwnerSay("llGetTimestamp()="+(string)llGetTimestamp());
llOwnerSay("llGetEnergy()="+(string)llGetEnergy());
llOwnerSay("llGetFreeMemory()="+(string)llGetFreeMemory());
llOwnerSay("llGetMemoryLimit()="+(string)llGetMemoryLimit());
}
}
- Output:
llGetTimestamp()=2012-07-18T01:26:12.133137Z llGetEnergy()=1.230000 llGetFreeMemory()=16000 llGetMemoryLimit()=65536
Lua
print( os.getenv( "PATH" ) )
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
Make
Make variables are initialized from the environment, so simply
TARGET = $(HOME)/some/thing.txt
foo:
echo $(TARGET)
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.
bar:
echo "$$HOME"
If you mistakenly write just $HOME
then it means the makefile $H
followed by characters OME
.
H = oops ...
bar:
echo $HOME
# prints oops ... OME
Maple
getenv("PATH");
Mathematica / Wolfram Language
Environment["PATH"]
MATLAB / Octave
getenv('HOME')
getenv('PATH')
getenv('USER')
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)
).
min
$PATH
Modula-3
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.
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 $ZF function, and if the permissions for the Caché process allow it you can perform operating system commands.
In Caché on OpenVMS in an FILES-11 filesystem ODS-5 mode these could work:
Set X=$ZF(-1,"show logical")
Set X=$ZF(-1,"show symbol")
NetRexx
When NetRexx runs under a JVM, system ENVIRONMENT variables are complimented by JVM system properties. This sample shows how to get both.
/* 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
- 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
> (env "SHELL")
"/bin/zsh"
> (env "TERM")
"xterm"
Nim
import os
echo getEnv("HOME")
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.
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.
Nu
$env.HOME
Objective-C
[[NSProcessInfo processInfo] environment]
returns an NSDictionary of the current environment.
[[[NSProcessInfo processInfo] environment] objectForKey:@"HOME"]
OCaml
Sys.getenv "HOME"
Oforth
System getEnv("PATH") println
Oz
{System.showInfo "This is where Mozart is installed: "#{OS.getEnv 'OZHOME'}}
PARI/GP
getenv("HOME")
externstr("echo $HOME")
In older versions, the command must effectively be triple-quoted:
extern("echo \"\\\"$HOME\\\"\"")
The shell sees
echo "\"$HOME\""
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,
extern("echo Pi")
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:
print $ENV{HOME}, "\n";
The POSIX
module also has getenv()
which is the same thing as a function.
use POSIX 'getenv';
print getenv("HOME"),"\n";
Phix
without js -- none such in a browser, that I know of ?getenv("PATH")
Phixmonti
/# Rosetta Code problem: http://rosettacode.org/wiki/Environment_variables
by Galileo, 10/2022 #/
def getenv
" > output.txt" chain cmd if "Error!" else "output.txt" "r" fopen dup fgets swap fclose endif
enddef
"path" getenv print
PHP
The $_ENV associative array maps environmental variable names to their values:
$_ENV['HOME']
PicoLisp
: (sys "TERM")
-> "xterm"
: (sys "SHELL")
-> "/bin/bash"
Pike
write("%s\n", getenv("SHELL"));
- Output:
/bin/bash
PowerShell
Environment variables can be found in the Env: drive and are accessed using a special variable syntax:
$Env:Path
To get a complete listing of all environment variables one can simply query the appropriate drive for its contents:
Get-ChildItem Env:
Prolog
SWI-Prolog has the built in function getenv.
?- getenv('TEMP', Temp).
PureBasic
PureBasic has the built in funtion
GetEnvironmentVariable("Name")
Example
If OpenConsole()
PrintN("Path:"+#CRLF$ + GetEnvironmentVariable("PATH"))
PrintN(#CRLF$+#CRLF$+"NUMBER_OF_PROCESSORS= "+ GetEnvironmentVariable("NUMBER_OF_PROCESSORS"))
PrintN(#CRLF$+#CRLF$+"Press Enter to quit.")
Input()
CloseConsole()
EndIf
Python
The os.environ dictionary maps environmental variable names to their values:
import os
os.environ['HOME']
R
Sys.getenv("PATH")
Racket
#lang racket
(getenv "HOME")
Raku
(formerly Perl 6)
The %*ENV
hash maps environment variables to their values:
say %*ENV<HOME>;
REBOL
print get-env "HOME"
Retro
here "HOME" getEnv
here puts
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.)
/*REXX program shows how to get an environmental variable under Windows*/
x=value('TEMP',,'SYSTEM')
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.)
/*REXX program shows how to get an environmental variable under Windows*/
x=value('TEMP',,'ENVIRONMENT')
The brexx interpreter provides a getenv function for accessing environment variables:
x=getenv("PATH") /* Get the contents of the path environment variable */
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
see get("path")
Ruby
The ENV hash maps environment variable names to their values:
ENV['HOME']
Run BASIC
' ------- 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$
{{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
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);
}
}
- 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
sys.env.get("HOME")
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.
$ include "seed7_05.s7i";
const proc: main is func
begin
writeln(getenv("HOME"));
end func;
Sidef
The ENV hash maps environment variables to their values:
say ENV{'HOME'};
Slate
Environment variables at: 'PATH'.
"==> '/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games'"
Slope
(env "HOME")
Smalltalk
Use the OSProcess library to gain access to environment variables:
OSProcess thisOSProcess environment at: #HOME.
OSProcess thisOSProcess environment at: #PATH.
OSProcess thisOSProcess environment at: #USER.
SNOBOL4
The host(4) function returns a known environment variable.
output = host(4,'PATH')
end
Standard ML
OS.Process.getEnv "HOME"
returns an option type which is either SOME value or NONE if variable doesn't exist
Stata
Use the env extended macro function.
display "`:env PATH'"
display "`:env USERNAME'"
display "`:env USERPROFILE'"
Swift
print("USER: \(ProcessInfo.processInfo.environment["USER"] ?? "Not set")")
print("PATH: \(ProcessInfo.processInfo.environment["PATH"] ?? "Not set")")
True BASIC
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
Tcl
The env
global array maps environmental variable names to their values:
$env(HOME)
TXR
TXR can treat the environment vector as text stream:
@(next :env)
@(collect)
@VAR=@VAL
@(end)
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):
@(next :env)
@(gather)
HOME=@home
USER=@user
PATH=@path
@(end)
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:
@(next :env)
@(gather :vars (home user path (shell "/bin/sh")))
HOME=@home
USER=@user
PATH=@path
SHELL=@shell
@(end)
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.
$ ./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"
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:
echo "$HOME"
An ordinary variable can be marked as an environment variable with the export
command:
export VAR
Now child processes launched by the shell will have an environment variable called VAR
.
The Unix command "env" will print out all of the environment variables as key=value pairs on standard output.
Ursa
import "system"
out (system.getenv "HOME") endl console
Ursala
The argument to the main program is a record initialized by the run-time system in which one of the fields (environs) contains the environment as a list of key:value pairs.
#import std
#executable ('parameterized','')
showenv = <.file$[contents: --<''>]>+ %smP+ ~&n-={'TERM','SHELL','X11BROWSER'}*~+ ~environs
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'>
V (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 ${os.getenv('HOME')}')
}
- Output:
prompt$ v run environment-variables.v In the 64 environment variables, $HOME is set to /home/btiffin
Vedit macro language
Get_Environment(10,"PATH")
Message(@10)
Or with short keywords:
GE(10,"PATH") M(@10)
Visual Basic
Debug.Print Environ$("PATH")
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.
/* Environment_variables.wren */
class Environ {
foreign static variable(name)
}
System.print(Environ.variable("SHELL"))
which we embed in the following Go program and run it.
/* 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()
}
- 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.
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,$2D)<<8;
EnvVar:= "PATH"; \environment variable
I:= 0;
loop [J:= 0;
loop [C:= Peek(EnvSeg,I); I:= I+1;
if C = 0 then quit;
if C = EnvVar(J) then
[J:= J+1;
if J = 4 then
[Text(0, EnvVar); \show env. var.
loop [C:= Peek(EnvSeg,I); \ and rest of
I:= I+1; \ its string
if C = 0 then exit;
ChOut(0, C);
];
];
]
else J:= 5; \line must start with environment variable
];
if Peek(EnvSeg,I) = 0 then quit; \double 0 = env. var. not found
];
]
- Output:
PATH=\masm6;C:\;C:\CXPL;C:\UTIL;C:\DOS;C:\BORLANDC\BIN
Yabasic
peek$("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
System.getenv("HOME")
/home/craigd
System.getenv() //--> Dictionary of all env vars
- 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
- SmallBASIC
- 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
- EMal
- Erlang
- Euphoria
- F Sharp
- Factor
- Forth
- Fortran
- FreeBASIC
- Frink
- FunL
- FutureBasic
- 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
- Nu
- Objective-C
- OCaml
- Oforth
- Oz
- PARI/GP
- Perl
- Phix
- Phixmonti
- PHP
- PicoLisp
- Pike
- PowerShell
- Prolog
- PureBasic
- Python
- R
- Racket
- Raku
- REBOL
- Retro
- REXX
- Ring
- Ruby
- Run BASIC
- Rust
- Scala
- Seed7
- Sidef
- Slate
- Slope
- Smalltalk
- SNOBOL4
- Standard ML
- Stata
- Swift
- True BASIC
- Tcl
- TXR
- UNIX Shell
- Ursa
- Ursala
- V (Vlang)
- Vedit macro language
- Visual Basic
- Wren
- WrenGo
- XPL0
- Yabasic
- Zkl
- Pages with too many expensive parser function calls