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Use export Command in Linux / Unix

How do I use export command under a Linux or Unix-like operating systems to set variables on a bash shell?

You can export shell variables using the export command.

Syntax

The syntax is as follows:

export VAR

You can assign value before exporting using the following syntax:
export VAR=value

OR

VAR=value
export VAR

The export command will marks each VAR for automatic export to the environment of subsequently executed commands i.e. make the local shell variable VAR global.

Examples

To make the local shell variable called PATH type the following:

### export PATH ###
export PATH=$PATH:/usr/local/bin
echo "$PATH"

Set a new EDITOR variable:

export EDITOR=/usr/bin/vim

You need to add export statements to ~/.bash_profile or ~/.profile or /etc/profile file. This will export variables permanently:
$ vi ~/.bash_profile
Sample file

PATH=$PATH:$HOME/bin
export PATH
 
# set vim as a text editor
export EDITOR=/usr/bin/vim
 
# set colorful prompt 
export PS1='\[\e[1;32m\][\u@\h \W]\$\[\e[0m\] '
 
# set java_home
export JAVA_HOME=/usr/local/jdk

To see all a list of all exported variables and functions, enter:

export -p

Sample outputs:

declare -x COLORTERM="gnome-terminal"
declare -x DBUS_SESSION_BUS_ADDRESS="unix:abstract=/tmp/dbus-pODhldZ1lj,guid=6cfbd17d02f210f6de5e630b00000165"
declare -x DESKTOP_SESSION="gnome"
declare -x DISPLAY=":0.0"
declare -x GDMSESSION="gnome"
declare -x GDM_KEYBOARD_LAYOUT="us"
declare -x GDM_LANG="en_IN"
declare -x GNOME_DESKTOP_SESSION_ID="this-is-deprecated"
declare -x GNOME_KEYRING_CONTROL="/tmp/keyring-oDL07q"
declare -x GNOME_KEYRING_PID="2708"
declare -x GPG_AGENT_INFO="/tmp/seahorse-PBDijt/S.gpg-agent:2777:1"
declare -x GTK_MODULES="canberra-gtk-module"
declare -x GTK_RC_FILES="/etc/gtk/gtkrc:/home/vivek/.gtkrc-1.2-gnome2"
declare -x HOME="/home/vivek"
declare -x LANG="en_IN"
declare -x LANGUAGE="en_IN:en"
declare -x LOGNAME="vivek"
declare -x LS_COLORS="rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arj=01;31:*.taz=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.dz=01;31:*.gz=01;31:*.lz=01;31:*.xz=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.rar=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.jpg=01;35:*.jpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.axv=01;35:*.anx=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.axa=00;36:*.oga=00;36:*.spx=00;36:*.xspf=00;36:"
declare -x OLDPWD
declare -x ORBIT_SOCKETDIR="/tmp/orbit-vivek"
declare -x PATH="/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games"
declare -x PWD="/tmp/n"
declare -x SESSION_MANAGER="local/wks01:@/tmp/.ICE-unix/2727,unix/wks01:/tmp/.ICE-unix/2727"
declare -x SHELL="/bin/bash"
declare -x SHLVL="1"
declare -x SSH_AGENT_PID="2763"
declare -x SSH_AUTH_SOCK="/tmp/keyring-oDL07q/ssh"
declare -x TERM="xterm"
declare -x USER="vivek"
declare -x USERNAME="vivek"
declare -x WINDOWID="73400323"
declare -x WINDOWPATH="7"
declare -x XAUTHORITY="/var/run/gdm3/auth-for-vivek-DSw31c/database"
declare -x XDG_DATA_DIRS="/usr/share/gnome:/usr/share/gdm/:/usr/local/share/:/usr/share/"
declare -x XDG_SESSION_COOKIE="6cff67927ad82fca095a44640000001f-1336294442.327911-838315070"

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{ 5 comments… add one }
  • M P September 28, 2012, 2:17 pm

    Could you comment on the following unexpected (to me) behavior of the export command in bash and dash. Note the punctuation or lack thereof.
    ($ = prompt, # = output)

    standard/normal cases:
    $ echo -$bar -$foo
    # – –
    $ export bar=foo; echo -$bar
    # -foo
    $ echo -$bar
    # -foo
    $ bar=fu; export bar; echo -$bar
    # -fu
    $ echo -$bar
    # -fu
    $ bar=foo; echo -$bar
    # -foo
    $ echo -$bar
    # -foo

    And now for something different:
    $ foo=bar echo -$foo
    # –
    $ foo\=bar ; echo -$foo
    # fu=bar: command not found
    # –
    $ echo -$foo
    # –
    $ foo=bar export foo; echo -$foo
    # -bar
    $ foo=bear; export foo; echo -$foo
    # -bear
    $ `foo=bar` echo -$foo
    # -bar

    My question is basically, why does the shell appear to be automatically expanding a variable assignment (or “silently executing an assignment”) prior to an export, but not prior to another command like echo? Is export “special”? What other circumstances have behavior like export?

    The reason this came up is because I’ve seen a couple of example scripts that have a line similar to
    /bin/sh -c ‘DISPLAY=:0 some_GUI_program’
    Should this do anything in general? If so, why?

    (I’ve been using linux on and off for about 15 years now, including at one point administering a production linux box, but still feel like a complete n00b)

  • jack September 29, 2015, 10:54 pm

    in samples file

    “# set vim as a text editor
    export EDITOR=/usr/bin/bin”

    you mean /usr/bin/vim

  • Bhargavi January 21, 2016, 10:55 am

    Hi,
    Am porting my code base to run with a different toolchain. This new toolchain has the standard libraries defined in /usr/. When I export this path as “export PATH=$PATH:/usr/bin”, this path is added to the existing variable PATH. The output looked like,
    declare -x PATH=”/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/bin”
    So my understanding is that, the compiler still searches in /usr/local/sbin or /usr/local/bin first and uses libraries from there.
    But I want my compiler to look into toolchain_path for all standard libraries.
    How do I achieve it..??
    Thanks,
    Bhargavi

    • AndrewS March 7, 2016, 5:43 pm

      Simply swap it round to “export PATH=/usr/bin:$PATH”

      But if you’re specifically talking about the *compiler* search path, rather than the *shell* search path, then this is something different and you’ll have to check your compiler’s manual.

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