export environment variable from a bash script

February 1st, 2011 mysurface Posted in Bash, source | Hits: 204462 | 14 Comments »

You may want to create a bash script that export some environment variable for your shell, but infect every execution of bash script is a unique session, where the variable export within it can’t be carry backward back to the bash shell.

For example you have a env.sh which contains some environment variables

export HELLO=hello
export HELLO2=world

And you trying to execute the env.sh, then try to echo $HELLO $HELLO2 at your shell, you will get nothing.

The proper way to export environment variable from your script to your shell is using command source.

source env.sh
$ hello world

You can put your env.sh into /usr/bin, and you can do source env.sh at any location and it will still works. Just that you have to educate your users to use source instead of direct execute the script. But I realized that not much users aware of the source command.

There is always an alternative way to do the same thing in Linux world. You can create a new bash session from your bash script and make it stay there until user type ‘exit’. Bash support an interactive option for that.

bash -i

Ok, how to make use of it?

Let me gives you a case and explain why I wanna make use of bash -i instead of source.

As an embedded Linux programmer, sometimes I may need to compile some apps by using different set of toolchain based on the embedded device ‘s processor architecture. The common environment variable for toolchain are ARCH and CROSS_COMPILE. Besides that, I also want to remind the user regarding that particular shell is meant for building apps for embedded device, therefore I would like to change the color and format of existing bash prompt, which i can make use of PS1 variable.


export ARCH=arm
export CROSS_COMPILE=arm-none-linux-gnueabi-
export PS1="\e[31mBUILD_ARM \w \e[m\n\$"

bash -i

When execute build_arm.sh, the bash prompt will turn red, and environment variable for ARCH and CROSS_COMPILE will be set, until user type ‘exit’, everything will resume back to normal. Why? because bash -i interactively wait for user inputs.


More PS1 tips? checkout this Angelina Jolie.

14 Responses to “export environment variable from a bash script”

  1. Heya i’m for the first time here. I came across this board and I find It really useful & it helped me out a lot. I hope to offer one thing again and aid others like you helped me.

  2. The full pathname to the shell is kept in this environment variable. If it is not set when the shell starts, Bash assigns to it the full pathname of the current user’s login shell.

  3. Moreover Syn-flex Liquid Glucosamine and other Syn-flex
    ( Synflex ) Glucosamine supplements come in liquid form providing faster,
    more complete absorption compared to pills, and results in arthritic pain relief in as little as
    7 to 10 days. Complications of Skin Asscociated with Rheaumatoid Arthritis.
    Swimming is a very good overall exercise for arthritis suffers as the water takes the pressure off
    of your painful joints.

  4. Is your water safe? Unedited excerpts from local and national articles are available at http://www.midtennwaterproblem.com these articles will help you better understand what’s hidden in your most precious resource.

  5. Qui sait, cuando ca sony ericsson trouve, Il tiendrons encore quelques matchs signifiant gala. Et même cuando Vienne realised un terme à l’Ultraball, Collin restera le assistant.Nous publions le classement mondial des nation’s sur roots des matchs internationaux.put rappel, la technique se ‘vrrle rrtre assez straight forward, Permettez nous environnant les vous are generally présenter.les matchs (m) Rapporterons, Comme durante championnat, 3, 1 ou 0 ; durante cas environnant les v

  6. Although maximum site owners are familiar with these concepts,
    but they may lack the expertise to do it the correctly.

    Then consider yourself one of the few, true internet
    marketers. A internet marketing business, in a nutshell,
    a business that’s designed to run on the internet
    via a website.

  7. very good

  8. kar???k scriptler,hosting paketleri,kurumsal scriptler,e-ticaret scriptleri,ilan scriptleri,arkada?l?k scriptleri,emlak scriptleri,rent a car scriptleri,sosyal ag scriptleri,muhasebe scriptleri,haber scriptleri,dernek scriptleri,rehber scriptleri,otel scriptleri,mobilyac? scriptleri,turizm tatil scriptleri,ki?isel scriptler,firma scriptleri

  9. Seriously, such a invaluable web site

  10. You’ve great info listed here

  11. In Mobile Strike, t?ere a?e ? gre?t deal ?f different t?ings th?t you can build; each different building serves an comp?etely d?fferent purpose t??n the fol?owing.

  12. Sustain the amazing job !! Lovin’ it!

  13. I am genuinely delighted to read this web site posts which carries tons of useful data, thanks for providing these information.

Leave a Reply