Environment variable seems not set while it is in a shell script

Question

I have a shell script file ./bin/postactivate with following content:

#!/bin/sh

export STATIC_ROOT="/webapps/tsango/static/"
export MEDIA_ROOT="/webapps/tsango/media/"
export DATABASE_NAME="tsango"
export DJANGO_SETTINGS_MODULE="tsango.settings.vagrant"
export DATABASE_PASSWORD="password"
export BROKER_URL="amqp://tsango:password@localhost/tsango"
export DATABASE_USER="tsango"

I execute it with sudo sh ./bin/postactivate command. The command seems to run properly, i.e. no output from the command line.

However, when I use printenv to see the list of environment variables, none of the variables of the script is set.

I'm probably missing something... Can you tell me what?

why use sh to run it? You have a hash bash slash bin slash sh? Now set the execute bit, and you don't need to run it with sh. — ctrl-alt-delor, Feb 20 '20 at 19:47
Do you mean in the script like you have put in the title (but not shown in your code), or after the script (as would cause this problem)? — ctrl-alt-delor, Feb 20 '20 at 19:48
@ctrl-alt-delor Thanks for your answer. In fact I learnt that environment variables are linked to a process. That was the root cause of the issue. — mathcounterexamples.net, Feb 20 '20 at 19:56
I did not provide an answer. Just two comments: one a side note, and one a question. — ctrl-alt-delor, Feb 20 '20 at 20:01

icarus · Answer 1 · 2020-02-20T17:18:13.623

0

You should invoke the script as

source bin/postactivate

A process has environment variables. Let us assume your shell has a process id of 1003. You invoke sudo sh ./bin/postactivate. PID 1003 forks to create a new process, say 1108. process 1108 calls exec to change itself into sudo. sudo then changes itself into sh to process your script. So PID 1108 sets the environment variables for itself such as STATIC_ROOT. It then exits. Your shell (PID 1003) which was waiting for 1108 prints a new prompt, but nothing has changed in the environment for PID 1003.

edited Feb 20 '20 at 17:18

answered Feb 20 '20 at 17:11

icarus

17,920

Thanks for the answer. I'm a real dummy to linux... and wasn't even suspecting that environment variables are linked to processes. – mathcounterexamples.net Feb 20 '20 at 17:24

Environment variable seems not set while it is in a shell script

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