It's not POSIX, but both bash & zsh have real time queries built-in (of course, $(date) is an even older school substitute): t1=$((EPOCHSECONDS + 60))

It's not POSIX, but both bash & zsh have real time queries built-in (of course, $(date) is an even older school substitute): t1=$((EPOCHSECONDS + 60)) while [ $EPOCHSECONDS -lt $t1 ] do # curl ... && break # or whatnot done There is also EPOCHREALTIME which gives you a floating point to micro or nanoseconds (for bash/zsh), but only Zsh provides FP arithmetic. There are string-manipulation workarounds, of course. And, yes, with Zsh you might need a `zmodload zsh/datetime` in there. These variables seem "under known". EDIT: For example, you can get a quickie wall time measurement from a Zsh shell function like this: dt () { t0=$EPOCHREALTIME "$@" printf "%.7f wallSec\n" "$((EPOCHREALTIME-t0))" >&2 } And then you can actually run in your shell dt echo hi, moon without even a single fork/clone. (which you can confirm with an off to the side `strace -fv -o/dev/shm/dt.st -p WHATEVER_PID`, although I guess the culture these days is often to have even prompt printing launch a zoo of activity)