Extract the full contents of the files changed during a given commit

extractor-git.sh

#!/bin/bash

### Extract the changed files of a commit Usage:help
#
# Given a commit, extract the full file contents of that commit, and write them to the destination directory (outside the repo)
#
# 	extractor-git.sh {copy|cat} COMMIT DESTDIR
#
# 'cat' simply cats the data, but no file metadata is preserved. No change is made to the repo state
#
# 'copy' switches to the target branch/commit and copies files over to the destination, then switches back
#
###/doc

do_cat() {
	# +++++++++++++++++++++++++++++++++++++++
	# Cat each to destination
	echo "$files" | while read targetfile; do
		mkdir -p "$dest/$(dirname "$targetfile")"

		git show "$commit":"$targetfile" > "$dest/$targetfile"
	done
}

do_copy() {
	# +++++++++++++++++++++++++++++++++++++++
	# Checkout, copyover

	curbranch="$(git status|grep -oP "On branch .+"|sed 's/On branch //')"
	git checkout "$commit" || {
		echo "Could not switch to target commit - try stashing, or use 'cat' mode"
		exit 1
	}

	echo "$files" | while read targetfile; do
		mkdir -p "$dest/$(dirname "$targetfile")"
		cp "$targetfile" "$dest/$targetfile"
	done
	git checkout "$curbranch"
}

if [[ ! -d ./.git ]]; then
	echo "You must run this script from the root of the repo"
	exit 2
fi

action="$1"
commit="$2"
dest="$3"

# All files changed in the commit
files="$( git log -n 1 "$commit" --name-only |tail -n +2 | grep -vP '^(\s|[a-zA-Z]+:|$)' )"

"do_$action" "$commit" "$dest"