Git: check if a commit exists on a given branch

git merge-base --is-ancestor

For a low-level query about commit existence, use git merge-base with its --is-ancestor option. This command only returns the result through its exit status, so it’s most useful for scripting.

$ git merge-base --is-ancestor <commit> <branch>

This command will exit with a status of 0 (success) if the commit is found on the branch, 1 (failure) if it is not, or 128 if either the commit or the branch don’t exist.

For example, if the commit exists:

$ git merge-base --is-ancestor a4ca614 origin/main

$ echo $?
0

…and if it does not:

$ git merge-base --is-ancestor a4ca614 upstream/main

$ echo $?
1

git branch --contains

For a higher-level query that can check multiple branches, use git branch with its --contains option to list all branches that contain the commit.

$ git branch --contains <commit>

For example:

$ git branch --contains a4ca614
  delicious-jams
* main

The result here that the only local branches with that commit are delicious-jams and main.

Add -a (--all) to include remote-tracking branches in the output:

$ git branch -a --contains a4ca614
  delicious-jams
* main
  remotes/origin/HEAD -> origin/main
  remotes/origin/main

To query only certain branches, add their names. For example, to check only origin/main and upstream/main:

$ git branch -r --contains a4ca614 origin/main upstream/main
  remotes/origin/main

This result tells us that the commit appears in origin/main but not in upstream/main.

You can also use shell wildcard patterns to match branch names. For example, to check all upstream branches:

$ git branch -r --contains a4ca614 'upstream/*'

No output here means that no matching branches contain the commit.

Fin

May you find the commits you’re looking for!

—Adam