Bash implementation of versions manipulations based on semver compatible git tags

version

#!/bin/bash
# ISC License
#
# Copyright (c) 2019-present, Mykhailo Stadnyk <mikhus@gmail.com>
#
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

# Bash implementation of versions manipulations based on semver compatible git tags
# Usage:
# - print current version
#   $ ./version
# - print next prerelease version
#   $ ./version prerelease
# - print next patch version
#   $ ./version patch
# - print next minor version
#   $ ./version minor
# - print next major version
#   $ ./version major

VERSION=`git describe --tags`
RX_VERSION="^v([0-9]+)\.([0-9]+)\.([0-9]+)(-([^-+]+))?([-+](.+))?"

if [[ ${VERSION} =~ $RX_VERSION ]]; then
    major=${BASH_REMATCH[1]}
    minor=${BASH_REMATCH[2]}
    patch=${BASH_REMATCH[3]}
    prerelease=${BASH_REMATCH[5]}
    build=${BASH_REMATCH[8]}

    case $1 in
        major)
            major=$(( $major + 1 ))
            minor=0
            patch=0
            prerelease=""
            ;;
        minor)
            minor=$(( $minor + 1 ))
            patch=0
            prerelease=""
            ;;
        patch)
            patch=$(( $patch + 1 ))
            prerelease=""
            ;;
        prerelease)
    	    if [[ ${prerelease} = "" ]]; then
    	        prerelease=-0
    	    else
                prerelease=-$(( $prerelease + 1 ))
            fi
            ;;
        *) # Print version and exit
            echo ${VERSION}
            exit 0
            ;;
    esac

    VERSION="v${major}.${minor}.${patch}${prerelease}"
fi

echo ${VERSION}