How to compare two strings in dot separated versio

Question

Is there any way to compare such strings on bash, e.g.: 2.4.5 and 2.8 and 2.4.5.1?

Answer 1

You can recursively split on . and compare as shown in the following algorithm, taken from here. It returns 10 if the versions are the same, 11 if version 1 is greater than version 2 and 9 otherwise.

#!/bin/bash
do_version_check() {

   [ "$1" == "$2" ] && return 10

   ver1front=`echo $1 | cut -d "." -f -1`
   ver1back=`echo $1 | cut -d "." -f 2-`

   ver2front=`echo $2 | cut -d "." -f -1`
   ver2back=`echo $2 | cut -d "." -f 2-`

   if [ "$ver1front" != "$1" ] || [ "$ver2front" != "$2" ]; then
       [ "$ver1front" -gt "$ver2front" ] && return 11
       [ "$ver1front" -lt "$ver2front" ] && return 9

       [ "$ver1front" == "$1" ] || [ -z "$ver1back" ] && ver1back=0
       [ "$ver2front" == "$2" ] || [ -z "$ver2back" ] && ver2back=0
       do_version_check "$ver1back" "$ver2back"
       return $?
   else
           [ "$1" -gt "$2" ] && return 11 || return 9
   fi
}    

do_version_check "$1" "$2"

Source

Answer 2

For old version/busybox sort. Simple form provide roughly result and often works.

sort -n

This is escpecial useful on version which contains alpha symbols like

10.c.3
10.a.4
2.b.5

Answer 3

This is also a pure bash solution, as printf is a bash builtin.

function ver()
# Description: use for comparisons of version strings.
# $1  : a version string of form 1.2.3.4
# use: (( $(ver 1.2.3.4) >= $(ver 1.2.3.3) )) && echo "yes" || echo "no"
{
    printf "%02d%02d%02d%02d" ${1//./ }
}