Parse a semantic version string to a 32 bit integer and reverse

semver2number.sh

#!/bin/bash
# NOTE this works only with bash, not dash
# Based on:
#   https://gist.github.com/dislick/914e67444f8f71df3900bd77ccec6091
# NOTE: first digit is MSB contrary to the Javascript version linked above.
# This does not work for non-numerical strings but this should be easy to remedy
#   https://semver.org/#semantic-versioning-specification-semver

# Semantic Version string to numerical version
semver2num() {
  IN="$1"
  C=2
  NUMVER=0
  while IFS='.' read -ra ADDR; do
    for i in "${ADDR[@]}"; do
      N=$(($i<<10*$C))
      let NUMVER=$NUMVER+$N
      let C=$C-1
      if [ $C -eq -1 ]; then
        break;
      fi
    done
  done <<< "$IN"
  echo $NUMVER
}

# Numerical version to Semabtic Version string
num2semver() {
  NUMVER=$1
  S2=$(($NUMVER & 1023))
  S1=$(($NUMVER >>10 & 1023))
  S0=$(($NUMVER >>20 & 1023))

  echo "$S0.$S1.$S2"
}



VSTRING="3.2.4"
echo Original version string: $VSTRING

NUMERICAL=$(semver2num "$VSTRING")
echo Numerical version: $NUMERICAL

SEMVER=$(num2semver $NUMERICAL)
echo Semver: $SEMVER