How to use npm version to increment the counter behind the prepatch / preid suffix - npm

Question

I'm trying to find out how to correctly use npm version with prepatch (also premajor or preminor) / preid options to increment the counter behind the suffix.
e.g.:
I have a v.0.5.22 and want to append -rc
I used the command npm version prepatch --preid rc
then I get v.0.5.23-rc.0, fine so far.
but the next time I'm using the same command I end up with v.0.5.24-rc.0,
what I want is to get v.0.5.23-rc.1 instead
How can I only increment the counter behind -rc. and keep the patch number?
Or am I misunderstanding the purpose of prepatch / preid?

Answer 1

Alright, I'll answer my own question for future reference.
After having v.0.5.23-rc.0 the command to only bump the number behind the . has to be:
npm version prerelease
Then I would get v.0.5.23-rc.1.

Answer 2

An alternative to npm version would be to write a bash script.
Ended up with this, fetching the version from the package.json
#!/usr/bin/env bash
set -e
packageJsonLocation="../package.json"
current_version=$(grep '"version":' $packageJsonLocation | cut -d\" -f4)
pre=0
if [ -z "${current_version}" ]; then
echo "No version found in package.json"
exit 1
fi
if [[ $current_version =~ ^.*-.* ]]; then
# increment prerelease version
IFS='-' read -ra array_pre <<< "$current_version"
IFS='.' read -ra array <<< "${array_pre[0]}"
pre=$(( ${array_pre[1]} + 1))
else
IFS='.' read -ra array <<< "${current_version}"
fi
new_version="${array[0]}.${array[1]}.${array[2]}-${pre}"
echo "Pre version: ${current_version} -> ${new_version}"
# Output
2.9.3 -> 2.9.3-0
and
2.9.3-1 -> 2.9.3-2