How can I have my shell script echo to me that the script that it calls has failed?
#!/bin/sh
test="/Applications/test.sh"
sh $test
exit 0
exit 1
3 Answers
#!/bin/sh
if sh /Applications/test.sh; then
echo "Well done $USER"
exit 0
else
echo "script failed with code [$?]" >&2
exit 1
fi
The /Applications/test.sh script should be well coded to exit with conventional status. 0 if it's ok and > 0 if it fails.
Like you can see, no need to test the special variable $?, we use boolean expression directly.
Comments
I usually take the following approach:
#!/usr/bin/env bash
test="/Applications/test.sh"
sh "${test}"
exit_status=$?
if [[ ${exit_status} ]] ; then
echo "Error: ${test} failed with status ${exit_status}." >&2
else
echo "Success!"
fi
5 Comments
William Pursell
+1, but using
[[ will fail if /bin/sh is a primitive shell (eg, not bash). Safer to do: if ! test $exit_status = 0; then. Also, the failure message should probably be directed to stderr.
Gilles Quénot
$? is often used like in this post by noobs because they don't understands if true; then ...; else ...; fi
johnsyweb
@sputnick: …or by people who want to first test and then report the value.!
William Pursell
You can report the value with:
if $test; then echo Success; else echo "Error: $test failed with status $?" >&2; fi There's no need to for the exit_status variable.johnsyweb
@WilliamPursell: You can. I find my format more readable. Also, if another command gets added into the
then block, it will still work.In terms of best practice, you should not. If a script fails, it should emit an error message before it terminates so that its parent doesn't have to. The main reason for this is that the process knows why it is failing, while the parent can only guess. In other words, you should just write:
#!/bin/sh
test="/Applications/test.sh"
sh $test
Although really, it would be more typical to just write:
#!/bin/sh
/Applications/test.sh
test.sh will emit the necessary error message, and your script will return the same value as did test.sh. Also, in its current form your script will always be successful, even if test.sh actually failed because exit 0; exit 1 is pretty pointless: the exit 1 will never be called.
1 Comment
johnsyweb
Unfortunately, not all third-party scripts are so well behaved and sometimes it's necessary to wrap them.
test.shfollow the convention of returning 0 on success and non-zero otherwise?exitwould do anything in your example; the second is never reached, because you've already exited with the first.