How to determine if Git merge is in process

Question

Is there a Git command that can be used to determine if a merge is in-process (i.e. uncommitted)? I know I can simply check for .git/MERGE_HEAD, but is this pr

Answer 1

One trick is to use a Git command that will fail if a merge is in progress. You can then check the return code of the command. You'll also want to make sure that the command will not affect your working copy or index in the event that it succeeds. While there are many commands that fall into this category, one that seems appropriate is

git merge HEAD

which returns a 128 code if a merge is in progress, but 0 otherwise. Note that when a merge is not in-process, this command will simply print Already up-to-date since you are just merging with yourself. So, for scripting purposes, you can do this (in BASH)

git merge HEAD &> /dev/null
result=$?
if [ $result -ne 0 ]
then
    echo "Merge in progress."
else
    echo "Merge not in progress."
fi

Note that even with the --quiet flag of git merge, an in-process merge will still cause this command to print to the error stream. This is why I redirect its output to /dev/null.