topic Re: How to return variable to parent shell? in Operating System - HP-UX

How to return variable to parent shell?

Igor Sovin — Fri, 22 Apr 2005 00:13:15 GMT

Hi!

My problem is the following
For example I do
#sh
#a=1
#echo $a
1
#exit
#echo $a

#

How to get value of variable "a" in my parent shell?

thanx

Re: How to return variable to parent shell?

Biswajit Tripathy — Fri, 22 Apr 2005 00:17:52 GMT

exit $a

- Biswajit

Re: How to return variable to parent shell?

Igor Sovin — Fri, 22 Apr 2005 00:21:36 GMT

I tried that
it doesn't work

Re: How to return variable to parent shell?

Biswajit Tripathy — Fri, 22 Apr 2005 00:22:19 GMT

My last post will basically return value of $a to the
parent shell, so "echo $?" in parent shell after
execution would give the value of a (i.e 1 in your
example).

I'm not sure if that what you asked. If you want to
set the variable a in the parent shell, then that can't
be done. You can't set a parameter to some value
automatically in the parent shell. You can only set a
variable to a value in a child shell by using "export a".

- Biswajit

Re: How to return variable to parent shell?

Igor Sovin — Fri, 22 Apr 2005 00:26:08 GMT

sorry, I've mistaken
everything works
thank you!

Re: How to return variable to parent shell?

Biswajit Tripathy — Fri, 22 Apr 2005 00:26:35 GMT

See the following thread on the topic:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=14148

- Biswajit

Re: How to return variable to parent shell?

Bob_Vance — Sun, 24 Apr 2005 09:05:45 GMT

The thread mentioned only discusses using a temp file to store the value. This is a tried and true and good way to do it. However, you then have the little temp file housekeeping to contend with -- delete it , etc.

For simple cases and depending on what you're doing, you don't need a file. Simply use Command Substitution.

In the following, in the local shell, we're setting xx to the standard output of the execution of a child shell. The child shell does some testing and then echoes (to standard out) various values depending on the results of his tests. The parent shell (our shell) can then check the value of xx:

Pine3 ## touch /tmp/foo ;\
xx=$(
if [ -f /tmp/foo ]
then echo 'foo_exists'
else echo 'foo_gone'
fi
);\
if [ "$xx" = 'foo_exists' ]
then echo "\n**it's all good!**"
else echo "\n**crap! where's foo?**"
fi

**it's all good!**

Pine3 ## rm /tmp/foo ;\
xx=$(
if [ -f /tmp/foo ]
then echo 'foo_exists'
else echo 'foo_gone'
fi
);\
if [ "$xx" = 'foo_exists' ]
then echo "\n**it's all good!**"
else echo "\n**crap! where's foo?**"
fi

**where's foo?**

HTH
bv