Shell script to assist with branch management for tasks in git

Question

I found nvie's git branching model simple enough to grasp and suitable for my projects - but the frontend supplied at GitHub was far too complex for me to understand. Hence, I wrote this script to start and finish tasks, automatically running the related commands to speed it all up a bit (without it becoming too abstract/complex).

I've read a handful of tutorials on writing shell scripts but found it difficult to find one that emphasized on portability/POSIX compliancy. I'd like the script to run just fine in sh, dash, bash and zsh. Any feedback is appreciated - for one thing, I'm a bit unsure about where to use $variable and ${variable}...

Intended usage

When I want to create a new branch for a task I run this:

gittask.sh new feature name_of_feature

When I'm done:

gittask.sh done

Finishing a task has it automatically deduce by the branch name prefix (feature/release/hotfix) what to do next.

• Features are merged back into the development branch.
• Releases are continuously merged back into the development branch (bugfixes) and, once the release branch is considered stable enough (decided upon by the user), merged into master (with a tag), ending the release branch.
• Hotfixes are merged back into both the master (with a tag) and the development branch.

Branch model

I use two persistent/remote branches, master and development, as well as three temporary/local branches, feature, release and hotfix.

Master branch

• Persistent
• Remote branch
• Each merge into master equals a new tag

Development branch

• Persistent
• Remote branch

Feature branches

• Temporary
• Branch off from development
• Merge back into development
• Naming: "subject" or "issue#" if on issue tracker ("feature/" is prepended)

Release branches

• Temporary
• Branch off from development
• Merge back into development (continuously) and master (when done)
• Naming: "major.minor.z", e.g. "1.2.0" (z is defined by hotfix, "release/" is prepended)
• Signed tag needed when merging with master

Hotfix branches

• Temporary
• Branch off from master
• Merge back into development and master
• Naming: "x.y.fix", e.g. "1.2.1" (x, y is defined by release, "hotfix/" is prepended)
• Signed tag needed when merging with master

Script

#!/bin/sh
# gittask.sh: taskbased git branching utility
# This script requires that git has been installed and properly configured,
# that the remote "master" and "development" branches exist (locally too) 
# and that a network connection to the "origin" repository is established.
set -o errexit
usage()
{
 echo
 echo "Usage:"
 echo " gittask.sh new feature name_of_feature"
 echo " - Creates a new branch off from 'development' named"
 echo " 'feature/name_of_feature'."
 echo " gittask.sh new release name_of_release"
 echo " - Creates a new branch off from 'development' named"
 echo " 'release/name_of_release'."
 echo " gittask.sh new hotfix name_of_hotfix"
 echo " - Creates a new branch off from 'master' named"
 echo " 'hotfix/name_of_hotfix'."
 echo " gittask.sh done"
 echo " - Merges current branch into master and/or development"
 echo " depending on if it's a feature, release or hotfix."
}
delete_branch()
{
 # Infinite loop, only way out (except for Ctrl+C) is to answer yes or no.
 while true; do
 echo "Delete $current branch? "
 read yn
 case $yn in
 [Yy]* ) 
 git branch -d ${current}
 break
 ;;
 [Nn]* )
 echo "Leaving $current branch as it is."
 break
 ;;
 * )
 echo "Error: Please answer (y)es or (n)o."
 ;;
 esac
 done
}
define_tag()
{
 # Don't proceed until both variables have been set.
 while [ -z ${version_number} ] && [ -z ${version_note} ]; do
 echo "Enter version number (major.minor.fix): "
 read version_number
 echo "Enter version number note: "
 read version_note
 done
}
# Confirm that user is in a git repository, abort otherwise.
git status >/dev/null 2>&1 || { echo "Error: You're not in a git repository."; exit 1; }
# If "new", confirm that the required arguments were provided.
if [ "1ドル" == "new" ] && [ -n "2ドル" ] && [ -n "3ドル" ]; then
 
 # Validate 3,ドル only allow a-z (lower case), 0-9 and _ (underscore) in branch names.
 [ "${3//[0-9a-z_]/}" = "" ] || { echo "Error: Branch names may only consist of a-z, 0-9 and underscore."; exit 1; }
 case 2ドル in
 feature )
 git checkout development
 git checkout -b "feature/3ドル"
 exit 0
 ;;
 release )
 git checkout development
 git checkout -b "release/3ドル"
 exit 0
 ;;
 hotfix )
 git checkout master
 git checkout -b "hotfix/3ドル"
 exit 0
 ;;
 * )
 echo "Error: You didn't specify feature, release or hotfix."
 exit 1
 ;;
 esac
# If "done", proceed to determine current branch and by that what to do next.
elif [ "1ドル" == "done" ]; then
 current=`git branch | awk '/\*/{print 2ドル}'`
 case ${current} in
 feature* )
 echo "Merging into development branch..."
 git checkout development
 git merge ${current}
 git push origin development
 delete_branch
 exit 0
 ;;
 release* )
 echo "Merging into development branch..."
 git checkout development
 git merge ${current}
 git push origin development
 # Infinite loop, only way out (except for Ctrl+C) is to answer yes or no.
 while true; do
 echo "Merge into master (make a release)? "
 read yn
 case $yn in
 [Yy]* )
 echo "Merging into master branch..."
 git checkout master
 git merge ${current}
 define_tag
 git tag -s ${version_number} -m ${version_note}
 git push --tags origin master
 delete_branch
 break
 ;;
 [Nn]* )
 echo "Leaving branch master as it is."
 break
 ;;
 * )
 echo "Error: Please answer (y)es or (n)o."
 ;;
 esac
 done
 exit 0
 ;;
 hotfix* )
 git checkout master
 git merge ${current}
 define_tag
 git tag -s ${version_number} -m ${version_note}
 git push --tags origin master
 git checkout development
 git merge ${current}
 git push origin development
 delete_branch
 exit 0
 ;;
 * )
 echo "Error: You're not on a feature, release or hotfix branch."
 exit 1
 ;;
 esac
else
 echo "Error: You didn't provide the needed arguments."
 usage
 exit 1
fi

• totte: I've revised this post and script several times, only to discover a new shortcoming each time it has been submitted. I don't expect myself to write a perfect piece of text or code at the first attempt - but it's odd how some things only become apparent once spoken out aloud.

Answer 1

The following is one of my favorite "rosetta stone" like references:

Unix Shells

Answer 2

It seems fine for me. Just three minor things:

1. I'd consider calling the define_tag before the git merge or any other command which changes the current state of the repository. If a user press Ctrl+C they will find the repository in a different state than the beginning of the script.

2. In the define_tag I'd print the existing tags (or the last five or ten tags). It could help users to choose the next one.

3. There are same requirements in the comments:

   # This script requires that git has been installed and properly configured,
   # that the remote "master" and "development" branches exist (locally too) 
   # and that a network connection to the "origin" repository is established.
   

   You could check that git is installed properly and the required branches are exist at the beginning of the script.