semver increment in shell script - sh

Question

I am trying to implement a solution to increment a version. Here's what I have come up with:
#!/bin/sh -x
VAR=1.0.1 # retrieved from Gitlab API
case $1 in
patch)
TAG=${VAR%.*}.$((${VAR##*.} + 1))
;;
major)
TAG=$((${VAR%%.*} + 1)).0.0
;;
*)
tmp=${VAR%.*}
minor=${tmp#*.}
TAG=${VAR%%.*}.$((minor + 1)).0
;;
esac
echo $TAG
major & patch work as expected; however, I'm facing problems incrementing minor.
When bumping 1.0.1, the minor should be 1.1.0; however, my code produces 1.2.0. What am I doing wrong?
Some more info, the script is executed inside a GitlabCI pipeline.
Edit: Updated the code with the suggested answer from #jhnc

Answer 1

I would just:
#!/bin/sh
var=1.0.1
IFS=. read -r version minor patch <<EOF
$var
EOF
case "$1" in
patch) tag="$version.$minor.$((patch+1))"; ;;
major) tag="$((version+1)).0.0"; ;;
*) tag="$version.$((minor+1)).0"; ;;
esac
echo $tag
Works on alpine with ash.

Answer 2

Your computation for incrementing minor is:
TAG=${VAR%%.*}.$((${VAR##*.} + 1)).0
However, ${VAR##*.} gives the patch value, not the minor value, and thus your incorrect result.
To extract minor, you can use a temporary variable:
tmp=${VAR%.*}
minor=${tmp#*.}
TAG=${VAR%%.*}.$((minor + 1)).0
Alternatively, it may be more readable to set IFS and split the string on dots:
TAG=$(
echo "$VAR" | while IFS=. read major minor patch; do
# add sanity-checks here
case "$1" in
patch)
echo "$major.$minor.$((patch+1))"
;;
major)
echo "$((major+1).0.0"
;;
minor|*)
echo "$major.$((minor+1)).0"
;;
esac
done
)
You should probably add sanity-checks to ensure VAR is actually of form "digits dot digits dot digits".