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 submodule sync -q
        git pull -q
        git submodule update --init --recursive
        git log $LOCAL..$REMOTE --date=short --pretty=format:"     - New [%ad] : %s"
    else
        # Something is different.
        echo "The Git repository in $DIR needs to be merged."
        echo "This cannot be done automatically."
    fi
done