Git SemVer release savant

release.sh

#!/bin/bash

# Git Tag SemVer helpers
# Usage : !release <repo> <strategy>
#         !release some_repo patch|minor|major

# Get arguments of repository and release strategy...
REPO=$1
if [ "" == "$2" ]
	then
	STRATEGY="patch"
else
	STRATEGY=$2
fi
case "$STRATEGY" in
"patch")  echo "Preparing $REPO patch release."
    ;;
"minor")  echo "Preparing $REPO minor release."
    ;;
"major")  echo "Preparing $REPO major release."
    ;;
*) echo "Invalid strategy : $2, using patch strategy as failover. Preparing $REPO patch release."
	STRATEGY="patch"
   ;;
esac

# Initialization
ROOT_DIR=$(eval echo $HOME)
REPO_DIR="$ROOT_DIR/$REPO"
if [ ! -d "$REPO_DIR" ]; then
	# Attempt to fetch
    echo "Attempt to fetch $REPO"
	cd $ROOT_DIR;git clone git@github.com:your-github-username/$REPO.git --quiet
	if [ $? -eq 0 ]
	then
	    echo "Caching new repo : $REPO"
	else
	    echo "Invalid repo ($REPO), aborted."
		exit
	fi
else
	# Update
	echo "Updating to latest revision"
	{
		cd $REPO_DIR
		git checkout master
		git reset --hard
		git fetch origin
		git rebase origin/master
	} &> /dev/null
fi
cd $REPO_DIR

# Get necessary information
CURRENT_VERSION_STRING=(`git describe --tags $(git rev-list --tags --max-count=1)`)
CURRENT_VERSION=(`echo $CURRENT_VERSION_STRING | tr '.' ' '`) 
V_MAJOR_STRING=${CURRENT_VERSION[0]}

# Determine semver comps
V_MAJOR=`echo $V_MAJOR_STRING | sed 's/v//'`
V_MINOR=${CURRENT_VERSION[1]}
V_PATCH=${CURRENT_VERSION[2]}
OLD_VERSION="$V_MAJOR_STRING.$V_MINOR.$V_PATCH"

# Validating old version against latest head hash
OLD_VERSION_HASH=(`git rev-list $OLD_VERSION | head -n 1`)
HEAD_HASH=(`git log --pretty=format:"%H" -n 1`)
DIFF=(`git log --pretty=format:"* %s %h" $OLD_VERSION_HASH..$HEAD_HASH`)
if [ "" == "$DIFF" ]; then
	# No new changes yet
	echo "There are no new commits since $OLD_VERSION"
	exit
fi

case "$STRATEGY" in
"patch")
	V_NEW_MAJOR="$V_MAJOR"
	V_NEW_MINOR="$V_MINOR" 
	V_NEW_PATCH=$((V_PATCH + 1)) 
    ;;
"minor")
	V_NEW_MAJOR="$V_MAJOR" 
	V_NEW_MINOR=$((V_MINOR + 1)) 
	V_NEW_PATCH="0"
    ;;
"major")
	V_NEW_MAJOR=$((V_MAJOR + 1)) 
	V_NEW_MINOR="0"
	V_NEW_PATCH="0"
    ;;
esac
NEW_VERSION="v$V_NEW_MAJOR.$V_NEW_MINOR.$V_NEW_PATCH"

echo "Current Version: $OLD_VERSION"
echo "Target Version: $NEW_VERSION"

# Creating the tag
{
git tag $NEW_VERSION
git push origin --tags
} &> /dev/null
echo "Tag $NEW_VERSION created."

echo "All Done! "