A lean approach to managing git subtrees manually

README.md

Manage subtrees manually

A lean approach to managing git subtrees manually. Because git-subtree clutters the history graph and git-stree still does too much for me.

I wanted the simplest possible solution that does not require anything special and that does not modify a repository beyond what's required for the most basic approach.

So you may use this script to manage a subtree. But your repository won't depend on it.

Samples

Adding a subtree:

$ git sub add https://github.com/you/component.git

This clones the repository "component" into the directory "component". The directory is now in the staging area and ready to be committed. git-sub won't make any commits.

Later, when you want to update the "component" subtree do:

$ git sub update component

The updated files are now in the staging area and can be committed.

Usage

usage: git sub add    <repository> <prefix>
   or: git sub update <remote>

Use the optional prefix argument to put the repository into a subfolder. By default, repositories are put into the parent repository's root folder.

Cloning

Remotes don't get cloned. So you can't run

$ git sub update component

on a fresh copy. Instead, if you want to add or update a component with one command only use

$ git sub add https://github.com/you/component.git

because add also updates a component if it's already a remote.

Installation

Just put git-sub somewhere in your path and make it executable.

git-sub

#!/usr/bin/env bash

# Update subtree from remote name
#
# @param 1 - name of remote
update()
{
	[ "$1" ] || return $?

	git fetch --no-tags "$1" &&
		git merge -s subtree --squash "$1/master"
}

# Add (or update) a subtree from a repository URL
#
# @param 1 - URL of repository
# @param 2 - prefix for repository directory (optional)
add()
{
	local NAME=${1##*/}
	NAME=${NAME%.*}

	[ "$NAME" ] || return $?

	if git remote | fgrep "$NAME" &>/dev/null
	then
		update "$NAME"
	else
		git remote add "$NAME" "$1" &&
			git fetch --no-tags "$NAME" &&
			git read-tree --prefix="$2$NAME/" -u "$NAME/master"
	fi
}

# Print help
help()
{
	cat <<EOF
usage: git sub add    <repository> <prefix>
   or: git sub update <remote>
EOF
}

if [ "$0" == "${BASH_SOURCE[0]}" ]
then
	"${@:-help}"
fi