update bash variable everytime it is called

Question

In my .bashrc I'm setting a bash variable to the output of a script

export FOO=`/home/jist/tools/lookup1.pl`

This works great except that the output of that script can change during the day (mainly depending on if I'm on the company's VPN or not). So when I do something with the variable, I want it to re-execute the script and get the updated value. I have no idea how to do this? Can someone please help?

Thanks in advance.

A cronjob isn't ideal since the value might change and the variable might be used before the job is run. — Jistanidiot, Apr 12 '13 at 15:25
Make it a function emitting a refreshed value on stdout instead of a variable and always access it as `$(FOO)`? — William, Apr 12 '13 at 16:24
Never knew you could do functions with bash. Thanks! That really seems to be the easiest. — Jistanidiot, Apr 12 '13 at 19:19
@fedorqui: A cron job wouldn't work at all; it runs outside your `bash` shell process, so it can't update shell or environment variables. — Keith Thompson, Aug 27 '13 at 15:15

score 2 · Answer 1 · edited Sep 29 '20 at 16:37

As described in a comment by William:

Make it a function emitting a refreshed value on stdout instead of a variable and always access it as $(FOO)

That means:

# create the function: put this in your .bashrc
FOO() { /home/jist/tools/lookup1.pl "$@"; }

# use the function and store its output: do this whenever you want the current result
currentFooResult=$(FOO)

# or, to just print the result to stdout:
FOO

update bash variable everytime it is called

1 Answers1