How to set environment variables : linux, environment, set, variable

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02.24.2004 at 01:51AM PST, ID: 20895782

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7.8

How to set environment variables

Zones: Linux, Linux Distributions

Tags: linux, environment, set, variable

How do you set the PATH, JAVA_HOME or CLASSPATH in Redhat Linux?

I want to know how to set it such that when the OS is booted up, these variables are set. In Windows, this is done in the Control Panel -> System -> Advance -> Environment Variables.

I also want to know how you override the default variables in a particular shell. In Windows, we can do SET PATH=%PATH%;c:\newpath to override the default PATH.

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Question Stats

Zone: OS

Question Asked By: yongsing

Solution Provided By: majorwoo

Participating Experts: 5

Solution Grade: A

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02.24.2004 at 02:24AM PST, ID: 10439635

Rank: Master

da99rmd:

if you are using bash
export JAVA_HOME="/usr/java/jdk1.3.1_01"

and if you are using tcsh
setenv JAVA_HOME /usr/java/jdk1.3.1_01

to Add a extra path do this in bash
export PATH=$PATH:/hejsan

Assisted Solution

02.24.2004 at 02:27AM PST, ID: 10439654

Rank: Master

da99rmd:

sry didnt read the the middle questione

put that in /etc/bashrc if bash

and /etc/csh.login for tcsh

this applays to all users if you just want i to your self put only in

%HOME%/.bashrc or
%HOME%/.tcshrc

02.24.2004 at 02:29AM PST, ID: 10439661

Rank: Master

da99rmd:

type
env
to see what your env settings are and what shell you are using under SHELL

/Rob

02.24.2004 at 08:03AM PST, ID: 10441949

Rank: Master

majorwoo:

da99rmd is right, another way is if you are setting this up for multiple users it can set in /etc/profile and it will be set for all system users at bootup

02.24.2004 at 05:23PM PST, ID: 10446773

yongsing:

I am using bash. Should I edit /etc/bashrc or etc/profile?

How do I add the settings in the file? This is how /etc/bashrc looks like:

# /etc/bashrc

# System wide functions and aliases
# Environment stuff goes in /etc/profile

# by default, we want this to get set.
# Even for non-interactive, non-login shells.
if [ "`id -gn`" = "`id -un`" -a `id -u` -gt 99 ]; then
      umask 002
else
      umask 022
fi

# are we an interactive shell?
if [ "$PS1" ]; then
if [ -x /usr/bin/tput ]; then
if [ "x`tput kbs`" != "x" ]; then # We can't do this with "dumb" terminal
stty erase `tput kbs`
elif [ -x /usr/bin/wc ]; then
if [ "`tput kbs|wc -c `" -gt 0 ]; then # We can't do this with "dumb" terminal
stty erase `tput kbs`
fi
fi
fi
case $TERM in
      xterm*)
            if [ -e /etc/sysconfig/bash-prompt-xterm ]; then
                  PROMPT_COMMAND=/etc/sysconfig/bash-prompt-xterm
            else
            PROMPT_COMMAND='echo -ne "\033]0;${USER}@${HOSTNAME%%.*}:${PWD/#$HOME/~}\007"'
            fi
            ;;
      screen)
            if [ -e /etc/sysconfig/bash-prompt-screen ]; then
                  PROMPT_COMMAND=/etc/sysconfig/bash-prompt-screen
            else
            PROMPT_COMMAND='echo -ne "\033_${USER}@${HOSTNAME%%.*}:${PWD/#$HOME/~}\033\\"'
            fi
            ;;
      *)
            [ -e /etc/sysconfig/bash-prompt-default ] && PROMPT_COMMAND=/etc/sysconfig/bash-prompt-default
       ;;
esac
# Turn on checkwinsize
shopt -s checkwinsize
[ "$PS1" = "\\s-\\v\\\$ " ] && PS1="[\u@\h \W]\\$ "

if [ "x$SHLVL" != "x1" ]; then # We're not a login shell
for i in /etc/profile.d/*.sh; do
       if [ -r "$i" ]; then
       . $i
       fi
      done
fi
fi
# vim:ts=4:sw=4

02.24.2004 at 06:06PM PST, ID: 10446991

Rank: Master

jdfox:

The global /etc/profile and your own local ~/.bash_profile are read when the shell is invoked as an interactive login shell, for example when you open a remote terminal session to someone else's machine, or when you log into your own machine without X Windows running, or when you hit ctrl-alt-F1 from X Windows to start a virtual terminal session.

The global /etc/bashrc (if it exists) and your own local ~/.bashrc is read when the shell is invoked as an interactive non-login shell, for example when you open up a terminal window in Gnome or KDE.

So it sounds like you'll be wanting it in your /etc/bashrc if you want to set it for all users, or in your ~/.bashrc if it's just for you.

Assisted Solution

02.24.2004 at 07:09PM PST, ID: 10447344

yongsing:

This sounds really confusing. I just need to know the Linux's equivalent to Windows setting via Control Panel -> System -> Advance -> Environment Variables.

It would be good if you can show me what to add to the relevant file.

02.24.2004 at 07:37PM PST, ID: 10447439

Rank: Master

jdfox:

edit your ~/.bashrc with your favourite editor
add those export commands to the end of the file, that da99rmd told you about up in his first post.
save, exit the editor.
log out, log back in.

02.24.2004 at 08:09PM PST, ID: 10447573

Rank: Master

majorwoo:

/etc/profile
would be more akin to env variables in windows (as /etc/profile is independent of shell choices)

to set something in /etc/profile you simply do:

VARIABLE_NAME=VALUE_YOU_WANT_IT_TO_BE

and then add to the export line the variable name giving you something like:

export PATH USER VARIABLE_NAME

if you don't want to reboot (or log in/out) you can then type:
source /etc/profile

for all practical purposes though, for a one user system ~/.bashrc is the same

Accepted Solution

02.24.2004 at 08:28PM PST, ID: 10447639

Rank: Master

paullamhkg:

majorwoo all show you the way, only that you have to login/get into a console mode (dos mode like) and use your editor to edit the file /etc/profile as majorwoo suggested.

and you have to login as root (the super user of linux/unix)

02.24.2004 at 11:57PM PST, ID: 10448410

Rank: Master

da99rmd:

Im not realy in to windows but if the settings you are talking about in control pannel apply to all users or you want it to work that way put it in

/etc/bashrc

And if you just want the settings to the user you are using put it in your home directory in the file

.bashrc

/Rob

02.25.2004 at 06:54AM PST, ID: 10450833

Rank: Master

jdfox:

In Windows you open up a graphical dialogue, & click the "environment variables" button. In there you can set variables for all users (known in MS Windows as "system variables") or just for the currently logged-in user ("user variables" in Windows)

There's only one right way to do it in MS Windows. It doesn't always work, but at least you know you tried the right thing. :-)

With Linux you gain the freedom to do it different ways, but at the price of reading lots of turgid manuals, and learning the several ways to configure things. It might seem like a pain at first to learn this stuff, yongsing, but it's definitely worth it in the end.

02.25.2004 at 07:54AM PST, ID: 10451429

Rank: Master

majorwoo:

da99rmd,

/etc/bashrc woud apply to all users using the bash shell (which is indeed the default for many linux systems) however if a user is using a different shell /etc/bashrc would be ignored. Take a look at your /etc/passwd file, you will see something like:
guest:x:509:500::/home/guest:/bin/bash
indicating the user guest, uses the bash shell. If this here changed (if the user used a different shell such as /bin/csh, or alternatively if they launched their own new shell once logging in anythign entered in /etc/bashrc would not be read by that shell)

/etc/profile on the other hand is read by all user shells regardless of what the user has set

02.26.2004 at 12:52AM PST, ID: 10458270

Rank: Master

da99rmd:

jdfox, but then you end up lerning somthing on the way when you are using linux :)

majorwoo, thats correct but most users dont chsh :/

02.26.2004 at 04:56AM PST, ID: 10459685

Rank: Master

majorwoo:

for sure, I'm just arguing principle now. It "is" closer to the windows way ;-)

02.27.2004 at 12:26AM PST, ID: 10467428

yongsing:

Thanks guys!

06.25.2004 at 11:41AM PDT, ID: 11401329

dcrawford999:

Modify the file /etc/csh.login

something like this:

setenv PATH ".:/bin:/usr/bin:/usr/local/bin" <--note the . which sets up local dir in path

setenv JAVA_HOME "/opt/myjava"

to edit that path later use the following:

setenv PATH ".:${PATH}:/somewhere/new"

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