Run `git commit` from another directory

You can also use the environment variables $GIT_DIR and $GIT_WORK_TREE to the same effect as --git-dir and --work-tree

These are the steps to commit a file when you are in another directory:

git --git-dir=/path/to/my/directory/.git/ --work-tree=/path/to/my/directory/ add myFile
git --git-dir=/path/to/my/directory/.git/ --work-tree=/path/to/my/directory/ commit -m 'something'

You can use git -C <path>. From https://git-scm.com/docs/git/2.4.4

git -C <path>: Run as if git was started in <path> instead of the current working directory.