Keep all Git repositories in $HOME up-to-date

gitup.sh

#!/opt/schily/bin/bosh
# Update all Git repositories in/below $HOME.

# ---- VARIABLES

# Contains a list of (substrings of) directories to skip.
# It makes sense to not interfere with Go's own version control,
# and on macOS the ~/Library folder should not be traversed
# either.
BLACKLIST="$HOME/go/ $HOME/Library"

# Contains a list of Git repository directories.
# Currently, this is collected automatically, but it can be a
# manual list as well. Note that "find" on non-Schily shells
# usually does not have a "-call" parameter.
GITDIRS=`find $HOME -maxdepth 3 -name '.?*' -prune -o -type d -call '[ -e "$1/.git" ]' {} \; -prune -print`

# ---- CODE

repocount=0
for DIR in ${GITDIRS}; do
	# Blacklist check:
	allowed=1
	for BAN in ${BLACKLIST}; do
		substrings=`expr "$DIR" : "$BAN"`
		if [ $substrings -ne 0 ] ; then
			# This directory is in/below a blacklisted one.
			allowed=0
			break
		fi
	done

	if [ $allowed -eq 0 ]; then
		continue
	fi

	# This directory is promised to be not blacklisted.
	# Process it.
	repocount=`expr $repocount + 1`
	cd $DIR

	# Check the remote state:
	git fetch -q

	UPSTREAM=${1:-'@{u}'}
	LOCAL=`git rev-parse @`
	REMOTE=`git rev-parse "$UPSTREAM"`
	BASE=`git merge-base @ "$UPSTREAM"`

	if [ $LOCAL = $REMOTE ]; then
		# This repository is up-to-date.
		# Do nothing with it.
		continue
	elif [ $LOCAL = $BASE ]; then
		# The remote version is newer.
		echo "Updating Git repository: $DIR"
		git pull -q
		git log $LOCAL..$REMOTE --date=short --pretty=format:"     - New [%ad] : %s"
	else
		# Something is different.
		echo "The Git repository in $1 needs to be merged."
		echo "This cannot be done automatically."
	fi
done

if [ $repocount -gt 0 ]; then
	echo "Successfully processed $repocount repositories."
fi