til/git/programmatically-grab-sha-for-head-commit.md

Programmatically Grab SHA For Head Commit

When I use gh browse path/to/some-file.txt, it opens the browser to that file in GitHub. However, it targets the default branch (main) by default which is not very useful as a permalink because what that file looks like on main is liable to change.

There is a --commit flag you can use to have it instead open to that file at a specific commit SHA.

So what SHA do I pass as an argument to that flag?

Often what I would like to grab is a reference to the current version of the file which is whatever it looks like for the HEAD commit. But HEAD is another moving target reference. The git rev-parse command can translate HEAD into a specific SHA though.

❯ git rev-parse --short HEAD
3402428

❯ git rev-parse HEAD
3402428aadc02cfdc9825c8feb593443e72f50cd

Either of those will work. I can use a bash command substitution then to tie it all together into a single command:

❯ gh browse path/to/some-file.txt --commit=$(git rev-parse --short HEAD)

See man git-rev-parse for more details.