I have a program which returns always zero exit code, even in case of an internal error. In case of an error there is additional output to standard output like:
# always-zero-exit
Error: Line: 1, Column: 1
some further scary error description....
Can someone please advice how to make a short bash workaround like the one below:
# always-zero-exit > search-for-string-'Error'-and-returns-non-zero-if-found
As Biffen suggested in the comment, use ! grep ERROR_PATTERN.
Example:
# Tiny test command that exit with status 0 and
# prints errors into STDOUT:
echo 'Error: Line: 1, Column: 1' > out.log
! grep -q 'Error' out.log
echo $?
# Prints: 1
# Same, no errors:
echo 'Line: 1, Column: 1' > out.log
! grep -q 'Error' out.log
echo $?
# Prints: 0
You may want to use more complex error message processing, for example:
! grep -Pqi '(error|fail|exception)' out.log
Here, grep uses the following options:
-P : Use Perl regexes.
-i : Use case-insensitive matching.
-q : Quiet; do not write anything to standard output. Exit immediately with zero status if any match is found.
SEE ALSO:
grep manual