Getting return value from program ran in background

dbrazeau · 03-10-2010, 01:07 PM

I think my title pretty much explains it. I am writing a script and I want to start a program in the background, and when that program finishes I want to check the return value to make sure there was no error.

For example normal I would do something like this:
#!/bin/sh
program
if [ ! $? -eq 0 ]; then
echo "There was an error"
exit 1
fi

Now I want to do something like this:
#!/bin/sh
PRTN=`program1 &`
program2
if [ ! $? -eq 0 ]; then
echo "There was an error in program2"
exit 1
fi
if [ ! $PRTN -eq 0 ]; then
echo "There was an error program1"
exit 1
fi

In this case if program2 finishes before program1, I don't think the return value from program1 $PRTN would be valid at the time it is checked. Any suggestions on how to do something like this?

ntubski · 03-10-2010, 06:22 PM

Code:

program1 &
PID1=$!

if ! program2 ; then
   echo "There was an error in program2"
   exit 1
fi

if ! wait $PID1 ; then
   echo "There was an error in program1"
   exit 1
fi

dbrazeau · 03-10-2010, 06:43 PM

Thanks ntubski. I was going to something like this:

Code:

while [ ! -z "$(ps | grep program1)" ]; do
		sleep 3
done

if [ ! $PRTN -eq 0 ]; then
	echo "There was an error in program1"
        exit 1
fi

Your solution seems a little nicer, so I'll give that a try. Thanks.

Oh and how do the put your code in that code box in your reply?

ntubski · 03-10-2010, 07:01 PM

Quote:

Originally Posted by dbrazeau

Oh and how do the put your code in that code box in your reply?

Use code tags.

[code]
your code goes here
[/code]