Re: time command with shell builtins

[Dominik Vogt <dominik.vogt@xxxxxx>]

On Tue, Jan 24, 2023 at 10:32:35AM +0100, Mikael Magnusson wrote:
> On 1/23/23, Dominik Vogt <dominik.vogt@xxxxxx> wrote:
> > On Mon, Jan 23, 2023 at 07:31:12PM +0100, Mikael Magnusson wrote:
> >> On 1/23/23, Dominik Vogt <dominik.vogt@xxxxxx> wrote:
> >> > On Mon, Jan 23, 2023 at 02:42:05PM +0100, Roman Perepelitsa wrote:
> >> >> On Mon, Jan 23, 2023 at 2:40 PM Dominik Vogt <dominik.vogt@xxxxxx>
> >> >> wrote:
> >> >> >
> >> >> > Is it possible to get timing statistics of shell builtins too?
> >> >> > Timing "echo" isn't very interesting, but timing loop constructs
> >> >> > would be:
> >> >> >
> >> >> >   $ time while foo; do bar done
> >> >>
> >> >> This:
> >> >>
> >> >>     % time ( while foo; do bar; done )
> >> >
> >> > That wasn't really the question.  Of course I can time a loop by
> >> > writing a different command, or by putting it in a pipe or file.
> >> >
> >> >   $ time echo foo | true
> >> >
> >> > I just want to get timing statistics of loops either explicitly by
> >> > prepending "time" or implicitly with REPORTTIME.
> >>
> >> As Bart already mentioned, the answer to your question is "no", but
> >> you can avoid some downsides of the subshell (eg, if your loop has
> >> side effects that are relevant to the rest of the script etc), by
> >> using SECONDS:
> >> % () { typeset -F4 SECONDS=0; sleep 1; () { typeset -F3 SECONDS=0;
> >> sleep 0.43; echo $SECONDS }; sleep 1; echo $SECONDS }
> >> 0.431
> >> 2.4329
> >> (the downside here is obviously that it doesn't split out cpu/system
> >> time for you, only elapsed time).
> >
> > Well, the worst downside for me is that REPORTTIME does not work.
> > The use case is "oh, that command ran a long time, I'd really
> > like to know how long it took".  I see no solution for that if
> > re-running the command is no optiuon because it takes too long.
> >
> > At the moment I'm writing some automation scripts that run for
> > hours and print their progress.  I might want to kill them after a
> > few hours and see how many seconds they ran and compare it to the
> > progress output.
>
> What you can do at the moment is a) put the time in your prompt (and
> reset the prompt on accept-line), b) save the current time in preexec
> and compare it against the current time in precmd and print it out if
> it exceeds some threshold(, c) or both).

Good idea.  This is what I use now:

-- snip --
autoload -Uz add-zsh-hook
zmodload zsh/datetime

function preexec_recordtime() {
	typeset -g _zsh_time
	_zsh_time="$EPOCHSECONDS"
}
add-zsh-hook preexec preexec_recordtime

function __prompt_get_displaytime () {
	if ! (( ${+_zsh_time} )); then return 0; fi
	if ! (( ${+REPORTTIME} )); then return 0; fi
	if (( $EPOCHSECONDS - $_zsh_time > $REPORTTIME )); then
		printf " $[EPOCHSECONDS - _zsh_time]s"
	fi
	unset _zsh_time
}

PS1="<...>$(__prompt_get_displaytime)<...>"
-- snip --

The measurement is good enough at the moment.  Putting the result
in the prompt has the advantage of not polluting the terminal.

Ciao

Dominik ^_^  ^_^

--

Dominik Vogt