README.md

This function automatically grabs the latest git tag and, based on keyword (major, minor, patch), adds a new tag. (e.g. git_tag patch for v1.2.0 would create v1.2.1)

Drop this into your ~/.bash_profile and run source ~/.bash_profile to use it.

You can find all of my dotfiles here: https://github.com/drewbarontini/dotfiles

bash_profile

## ----- Tag ----- ##
## Automatically set a git tag based on Semantic Versioning keyword
## Note: This assumes you prefix your git tags with 'v' (e.g 'v1.2.0')
##
## $1 - 'major', 'minor', 'patch'
##
## Usage: `git_tag major`
##

function git_tag() {
  local tag=$(git describe --abbrev=0 --tags)
  local prefix=$(echo $tag | grep -o --color=never "^[A-z]\+")
  local major=$(echo $tag | cut -d '.' -f1 | sed "s/^$prefix//")
  local minor=$(echo $tag | cut -d '.' -f2)
  local patch=$(echo $tag | cut -d '.' -f3)

  case "$1" in
    'major')
      local nmajor=$(($major+1))
      local version="$nmajor.0.0"
      ;;
    'minor')
      local nminor=$(($minor+1))
      local version="$major.$nminor.0"
      ;;
    'patch')
      local npatch=$(($patch+1))
      local version="$major.$minor.$npatch"
      ;;
    *)
      echo "Automatically set a git tag based on Semantic Versioning keyword"
      echo
      echo "Usage: git_tag <major|minor|patch>"
      echo
      echo "Example:"
      echo "  git_tag major"
  esac

  if [[ "$version" ]]
  then
    git tag -a "$prefix$version" -m "Version $version"
    echo "$prefix$version created!"
  fi
}

Differs from original in that: don't leak as globals, v tag prefix is optional, and it prints usage text if you don't give it one of the SemVer keywords.