How to exit a git hook script if a git command fails?

Question

I have a post-receive git hook:

#!/bin/bash

while read oldrev newrev refname
do
    branch=$(git rev-parse --symbolic --abbrev-ref $refname)
    if [ -n "$branch" ] && [ "master" == "$branch" ]; then
       working_tree="/path/to/working/dir"
       GIT_WORK_TREE=$working_tree git checkout $branch -f
       GIT_WORK_TREE=$working_tree git pull
       <more instructions>
    fi
done

How can I check the status of a git command and stop the script from continuing if it fails?

Something like the following:

#!/bin/bash

while read oldrev newrev refname
do
    branch=$(git rev-parse --symbolic --abbrev-ref $refname)
    if [ -n "$branch" ] && [ "master" == "$branch" ]; then
       working_tree="/path/to/working/dir"
       GIT_WORK_TREE=$working_tree git checkout $branch -f
       GIT_WORK_TREE=$working_tree git pull
       if [ <error conditional> ]
           echo "error message"
           exit 1
       fi
    fi
done

Run it with /bin/bash -e (or set -e == set -o errexit) and the shell will do it automatically for you whenever an unchecked command fails. — Petr Skocik
– Petr Skocik, Commented Aug 3, 2017 at 22:05
@PSkocik -e is generally discouraged because of its unintuitive semantics. See Why does set -e not work inside () ||. — user743382
– user743382, Commented Aug 3, 2017 at 22:11
@hvd Yeah, that absolutely sucks about set -e, but I still think simple shell scripts should be set -e by default. Too bad one can't rely on it in libraryish shell functions, exactly because of the behavior you mention. :( — Petr Skocik
– Petr Skocik, Commented Aug 3, 2017 at 22:15
It's worth noting here that exiting the post-receive function has no effect on the push, and error messages from post-receive may also be entirely invisible. A post-receive script usually has to use something that smells like syslog to capture problems. — torek
– torek, Commented Aug 4, 2017 at 0:35

larsks · Accepted Answer · 2017-08-03 22:01:29Z

3

How can I check the status of a git command and stop the script from continuing if it fails?

The same way you check the status of any shell command: by looking at the return code. You can inspect the value of the shell variable $? after the command exits, as in:

GIT_WORK_TREE=$working_tree git pull
if [ $? -ne 0 ]; then
  exit 1
fi

Or by using the command itself as part of a conditional, as in:

if ! GIT_WORK_TREE=$working_tree git pull; then
  exit 1
fi

answered Aug 3, 2017 at 22:01

larsks

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3 Comments

user743382 Over a year ago

This seems needlessly verbose. || exit 1 is enough.

larsks Over a year ago

Not if you want to emit some sort of useful error message (which the OP is doing in the question).

user743382 Over a year ago

And which you aren't doing in your answer. If you want to emit a useful error message, I'd go with ||, but in combination with a shell function myself: something along the lines of || fail "command failed", with fail() { echo "error: $1" >&2; exit 1; }. This doesn't distract as much when you're reading the script later.

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