precommit hook for R package. Adds a 'GitCommit' to the DESCRIPTION field.

pre-commit

#!/bin/sh
#
# This updates the GitCommit field of the DESCRIPTION file with the git commit
#  sha (and branch). You should commit before building to make sure yours line up.
# Then going to that sha will give you that version of the package.
#
# It goes in ~/phd/.git/modules/rphd/hooks (or if not a submodule, in .git/hooks)

#echo $(pwd) ~/phd/rphd
BRANCH=$(git rev-parse --abbrev-ref --verify HEAD )
SHA=$(git rev-parse --short --verify HEAD)

DESC=DESCRIPTION

# replace GitCommit with current git sha.
# so you can `git checkout SHA` and you will get that version of the package.
# (so if you want the newest version of the package, you commit THEN build).
sed -i -r -e 's/^GitCommit:.+$/GitCommit: '$BRANCH'-'$SHA'/' $DESC
git add $DESC

exit 0