Using Floating Points In Bash Script

Question

I have this Bash script that has a basic if...else operator but the script doesn't seem to recognise the values correctly, and just continues the script, when it should stop and show an error.

I believe it's because I am using a float number, and bash can't tell. Here's the script:

Note: the error function is just a customer function

while getopts ":mh" opt; do
    case $opt in
        m)
            version="${OPTARG}"
            ;;
        \?)
            error "-$OPTARG is not a valid option. Use '-h' for more options" 'warn'
            ;;
        *|h)
            usage
            ;;
    esac
done
echo ${version} # here for debugging - this is either blank, or '0'
shift $((OPTIND-1))

[[ -z ${version} ]] && version=5.7

[[ "${version}" -lt "5.5" || "${version}" -gt "5.7" ]] &&
    error "Valid MySQL versions: 5.5 - 5.6 - 5.7" 'error'
echo ${version} # this then becomes '5.7' further down the script

So obviously I want the script to exit if the value of -m is less than 5.5 or greater than 5.7. Again I think it's to do with the value being a float.

Any help is appreciated.

Note that version numbers are rarely decimal numbers. 1.2 < 1.10, etc. — Biffen, Jan 28 '16 at 08:45

Joao Morais · Answer 1 · 2016-01-28T09:15:32.170

0

You can use bash expansion to take a default version and regex to validate them. It is better to validate with regex instead -le and -ge because you can specify a list of valid options.

version=${version:-5.7}
[[ "$version" =~ ^(5\.5|5\.6|5\.7)$ ]] || error "Valid MySQL versions: 5.5 - 5.6 - 5.7"

edited Jan 28 '16 at 09:15

answered Jan 28 '16 at 09:09

Joao Morais

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1

Or `^5\.[567]$`. (At least escape the `.`.) – Biffen Jan 28 '16 at 09:12
@Biffen perfect, forgot to escape de dots, thanks. – Joao Morais Jan 28 '16 at 09:16

Using Floating Points In Bash Script

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