Bash - Integer Expression Expected

Answer :

The test command, also named [, has separate operators for string comparisons and integer comparisons:

INTEGER1 -eq INTEGER2

INTEGER1 is equal to INTEGER2

vs

STRING1 = STRING2

the strings are equal

and

STRING1 != STRING2

the strings are not equal

Since your data is not strictly an integer, your test needs to use the string comparison operator. The last realization in the comments was that the "-eq" logic did not match the sense of the if/else echo statements, so the new snippet should be:

... if [ "$x" != "$y" ] then        echo There is version $y update else        echo Version $x is the latest version fi 

BTW, if you have two version strings (e.g. in $x and $y) you can use printf and GNU sort to find which is newer.

$ x=4.1.1 $ y=4.2.2 $ printf "%s\n" "$x" "$y" | sort -V -r 4.2.2 4.1.1  $ if [ $(printf "%s\n" "$x" "$y" | sort -V -r | head -1) = "$x" ] ; then   if [ "$x" = "$y" ] ; then     echo "$x is equal to $y"   else     echo "$x is newer than $y"   fi else   echo "$x is older than $y" fi 4.1.1 is older than 4.2.2