Find the hash of a file in Git history

Question

I try to find the hash of a file at a given point in the history.

git ls-files $REVISION $PATH | \
  sed -n 's/^.\{6\} .\+ \([0-9a-f]\{40\}\)\t.*$/\1/p'

works, but it looks rather inelegant. It displays mode, type, hash and path to then use sed to filter out only the hash. Is there some command that only prints the hash to begin with?

I imagine to have overlooked something more straightforward like git show --pretty=%hash $REVISION:$PATH. Does a Git command like this exist?

Answer 1

Git provides the rev-parse command for printing the SHAs of various items. Unlike many Git commands (pretty much everything but git show) it uses a colon as a separator between revisions and paths.

git rev-parse $REVISION:$PATH