Bash function to record duration, with concurrent timer support

timer.sh

#!/bin/bash
# Record time duration, concurrent timers

timer() {
    [[ $1 =~ ^[0-9]+$ ]] && {
        [[ $n -gt $1 ]] || n=$1; local i=$1; shift; }
    [[ $1 == -n ]] && { n=$(( n + 1 )); shift; }
    [[ $1 == -p ]] && { n=$(( n - 1 )); shift; }
    [[ $1 == -c ]] && { local i=$n; shift; }
    [[ -n $1 ]] || say -n err 'No timer action specified.'
    [[ $1 == start ]] && tstart[$i]=$SECONDS
    [[ $1 == stop  ]] && {
        [[ -n ${tstart[$i]} ]] || say -n err 'Timer %s not started.' "$i"
        tstop[$i]=$SECONDS; duration[$i]=$(( tstop[i] - tstart[i] )); }
    [[ $1 == show ]] && {
        [[ -n ${tstop[$i]} ]] || duration[$i]=$(( SECONDS - tstart[i] ))
        echo ${duration[$i]}; }
    return 0
}

This uses my say function from before, but those lines could be changed to use printf instead.

Updated version in my utility functions module.