Git update hook to deploy files of a pushed branch into a corresponding worktree if it exists. The id of the worktree should match the branch name (rename/move if necessary). See https://git-scm.com/docs/git-worktree

update

#!/bin/sh

# Exit if any unhandled command fails
set -e

# --- Command line
refname="$1"
oldrev="$2"
newrev="$3"

# --- Safety check
if [ -z "$GIT_DIR" ]; then
        echo "Don't run this script from the command line." >&2
        echo " (if you want, you could supply GIT_DIR then run" >&2
        echo "  $0 <ref> <oldrev> <newrev>)" >&2
        exit 1
fi

if [ -z "$refname" -o -z "$oldrev" -o -z "$newrev" ]; then
        echo "usage: $0 <ref> <oldrev> <newrev>" >&2
        exit 1
fi

# if $newrev is 0000...0000, it's a commit to delete a ref.
zero="0000000000000000000000000000000000000000"

branch=${refname#refs/heads/}

#echo "oldrev=${oldrev} newrev=${newrev} refname=${refname} branch=${branch}"

[ "$refname" = "refs/heads/${branch}" ] || exit 0

case "$branch" in
    ""|"__empty__")
        echo "Invalid branch name '$branch'" >&2
        exit 1
        ;;
esac

branch_git_dir="${GIT_DIR}/worktrees/${branch}"
unset GIT_DIR

if [ ! -d ${branch_git_dir} ]; then
    echo "No worktree found for branch $branch. Skipping deploy."
    exit 0
fi

target="$(dirname "$(cat $branch_git_dir/gitdir)")"
folder="$(basename "$target")"

if [ ! -d ${target} ]; then
    echo "Worktree $target for branch $branch is unavailable. Abording." >&2
    exit 1
fi

currev="$(git -C "$target" rev-parse HEAD 2>/dev/null)" || currev=$zero

if [ "$oldrev" != "$currev" ]; then
    echo "Warning! The current checked out revision $currev differs from the expected revision $oldrev."
fi

echo "Deploying branch '$branch' to '$target'"

if [ "$currev" != "$zero" ]; then
    oldstash="$(git -C "$target" rev-parse -q --verify refs/stash)" || oldstash=$zero
    git -C "$target" stash save -q "In worktree $folder: On commit $currev: Local changes"
    newstash="$(git -C "$target" rev-parse -q --verify refs/stash)" || newstash=$zero
    [ "$oldstash" == "$newstash" ] || echo "Warning! Saved local changes to stash."
fi

untracked_files=$(git -C "$target" ls-files --other --directory --exclude-standard)

if [ -n "$untracked_files" ]; then
    echo "Warning! Untracked files exist in folder $folder:"
    echo "$untracked_files"
fi

if [ "$newrev" != "$zero" ]; then
    echo "Checking out $newrev"
    git -C "$target" checkout -q --detach $newrev
else
    echo "Removing all files"
    git -C "$target" checkout -q --orphan __empty__
    git -C "$target" rm -rf --ignore-unmatch .
fi

echo "Success! Revision $newrev is now deployed to '$folder'"

# --- Finished
exit 0