BASH export command

galalleni · 09-03-2003, 12:40 AM

Howdy,
My shell script enviroment variables are not exported (yes, I used export) to the parent shell. This is true of root and user accounts. Although, /etc/profile script env. vars export correctly. This occured after I upgraded to Slackware 9.0.

Here is the sample script I am debugging:

Code:

#!/bin/bash
# sample.sh Foobar script
#
FOOBAR="Hello World"
export FOOBAR

Then I try,

Code:

somebody@network:~# ./sample.sh
somebody@network:~# echo $FOOBAR

somebody@network:~#

, but this works:

Code:

somebody@network:~# FOOBAR="Hello World"; export FOOBAR
somebody@network:~# echo $FOOBAR
Hello World
somebody@network:~#

Yes, my script has exec permission. I am hoping I don't have to recompile bash (like I did for ISC dhclient, because something is broken in the package - I had to use the source tarball from ISC). And many hours/google searches later I ended up here. Any Ideas?

Thanks in adv. for any help (/sympathy)!!

arakno · 09-03-2003, 02:29 AM

I may be wrong but I think enviroment variables in bash scripts are supposed to be used within the script.

Here, to setup 'global' bash variables, I use ~/.bash_profile

Example:

Code:

export CHARSET=ISO8859-1

yuray · 09-03-2003, 05:08 AM

Run:
. ./sample.sh

dot first !

eric.r.turner · 09-06-2003, 11:20 PM

The export command makes the value of a variable available to the current process and to subprocesses, but not to parent processes!

When you create a shell script and execute it, a new shell process is started to execute the contents of that script. Any exported variable values are available to the new shell, or to any subprocesses the new shell creates. When the script ends, none of the exported variable values are available to the parent process (your login shell).

When you log in, the first thing that the login shell does is runs your login script (e.g. ~/.bash_profile), which is why any exported variable values in that script are available to you from that point on.

Adding the . before you execute sample.sh (for example: . ./sample.sh) will work. The . is a shell builtin command that causes the script to be read and executed in the current shell process rather than starting a new shell process to do that. That is why exported variable values are available to your login shell. You can do the same thing with "source ./sample.sh" since source and . mean the same thing.

galalleni · 09-08-2003, 12:44 AM

Thank you! I forgot about the source command (I need to brush up on my BASH scripting).