Simple way to convert HH:MM:SS (hours:minutes:seconds.split seconds) to seconds

Question

What\'s an easy way to convert 00:20:40.28 (HH:MM:SS) to seconds with a Bash script?

Split seconds can be cut out, it’s not essential.

Answer 1

I have this old shell function (/bin/sh compatible in the sense of POSIX shell, not bash) which does this conversion in integer math (no fractions in the seconds):

tim2sec() {
    mult=1
    arg="$1"
    res=0
    while [ ${#arg} -gt 0 ]; do
        prev="${arg%:*}"
        if [ "$prev" = "$arg" ]; then
            curr="${arg#0}"  # avoid interpreting as octal
            prev=""
        else
            curr="${arg##*:}"
            curr="${curr#0}"  # avoid interpreting as octal
        fi
        curr="${curr%%.*}"  # remove any fractional parts
        res=$((res+curr*mult))
        mult=$((mult*60))
        arg="$prev"
    done
    echo "$res"
}

Outputs:

$ tim2sec 1:23:45.243
5025

It works with SS, MM:SS and HH:MM:SS only :)