Bumping version tags with git

December 27th, 2023 at 17:17

It is common to use git tags to manage software version numbers. Such tags are often done with a “v” followed by the version, eg “v1.2.3”. I decided I wanted to make managing these a little easier, so I made a git alias to make a new tag with the next version for me.

I looked at various Stackoverflow and other posts for ways to manage this. I found some nice looking git alias options that seemed to make a lot of sense. They mostly did what I wanted, but I had to tweak them a bit to get something that I liked well and to handle the multiple parts of the version with one command.

My alias can be called as git bump followed by one, two or three dots, or string patch, minor, or major to tell it which part of the version string to bump. With version 1.2.3:

. or patch will make the version 1.2.4
.. or minor will make the version 1.3.0
... or major will make the version 2.0.0

The naming and version format follows Semantic Versioning conventions. I’m not supporting extension like “rc” and “beta” because those would be hard, it’s much less obvious what to do, and I don’t use them on the small projects I work on anyway.

Git aliases can be put in ~/.gitconfig (create it if it doesn’t exist). For this functionality, I added something like:

[alias]
    versionbump = !"cd -- ${GIT_PREFIX:-.} && V=$(git tag --sort=-version:refname --list \"v[0-9]*\" | head -n 1) \
        && if [ -z \"$V\" ]; then V='v0.0.0'; fi \
        && if [ \"$1\" == '.' ] || [ \"$1\" == 'patch' ]; then \
                awkV='{OFS=\".\"; $NF+=1; print $0}'; \
            elif [ \"$1\" == '..' ] || [ \"$1\" == 'minor' ]; then \
                awkV='{OFS=\".\"; $2+=1; $3=0; print $0}'; \
            elif [ \"$1\" == '...' ] || [ \"$1\" == 'major' ]; then \
                awkV='{OFS=\".\"; $1+=1; $2=0; $3=0; print \"v\"$0}'; \
            else echo 'No version specified.  Specify one of patch, minor, or major.'; exit 1; \
        fi \
        && if [ -z \"$awkV\" ]; then exit 1; else newV=$(echo $V | awk -F. \"$awkV\"); fi \
        && read -r -p \"Do you want to tag with version ${newV}?: \" tmp \
        && ([[ $tmp =~ ^[Yy] ]] && git tag \"${newV}\" \"${@:2}\") && echo \"Tagged version ${newV}\" \
        || exit 1 #"
    bump = !git versionbump
    vb = !git versionbump

I did versionbump as the full name to be explicit, plus some shorter aliases to make it quick to type. I use the ! to run a full shell command, as I have too much going on for a straight alias. Note my implementation depends on running in bash / zsh, and requires some common POSIX utilities such as head and awk.

The GIT_PREFIX part ensures this works even when specifying a different git repo. The git tag part gives a list of version formatted tags and sorts them by version (the version:refname part ensures they are properly sorted as version strings). The head -n 1 gives us the first one only. The first if sets the version to 0.0.0 if there isn’t a version set yet. The nested if structure that follows uses the argument to determine which version piece to bump, and sets the appropriate awk command in a variable. awk does the actual string manipulation on the current version. The next couple lines run that and then verify with the user that the version string looks right (typing anything but a “y” or “Y” cancels the bump. If yes, then a git tag command is run to actually do the tagging. The trailing # is needed to prevent arguments from being appended.

I like it. Makes managing versions a lot easier for me.

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