I use this to tag commits when I'm ready to deploy to production. I made this so I don't have to remember what the last version was, and so I don't have to type the command either. To use as a git command (git nexttag) save it as git-nexttag somewhere on the path, like /usr/local/bin.

git nexttag

#!/bin/bash

lasttag=$(git describe --abbrev=0 --tags)

tagparts=(${lasttag//./ })

if [ ! -z $1 ]  && [ $1 == "--hotfix" ]
 then
	declare -i hotfix
	hotfix=1
	if [ ${tagparts[2]} ]
	 then
	 	hotfix=${tagparts[2]}+1
	fi

	newVersion=${tagparts[0]}.${tagparts[1]}.$hotfix
	message="Version 1.$stringMinorVersion Hotfix #$hotfix"
else
	declare -i newMinorVersion
	newMinorVersion=${tagparts[1]}+1
	stringMinorVersion="$(printf "%02d" $newMinorVersion)"
	newVersion=${tagparts[0]}.$stringMinorVersion
	message="Version 1.$stringMinorVersion"
fi

git tag -a $newVersion -m "$message"