On Sun, Dec 17, 2023 at 10:12:11AM +0000, Albretch Mueller wrote:
> dt00=$(date +%Y%m%d%H%M%S)
> echo "// __ \$dt00: |${dt00}|"
>
> ... after some long processing for which seconds would be exact
> enough, then I would like to get the seconds elapsed since dt00, like
> this:
>
> dt02=$(date +%Y%m%d%H%M%S)
> echo "// __ \$dt02: |${dt02}|"[...] > because bash Arithmetic is 10-based. You wouldn't expect bash to intuit such a crooky arithmetic as Gregorian datetime (and then, based on what? The number beginning with 2023? Sounds kind of exciting). If you could live with a datetime format which date can understand (instead of your cobbled-up pseudo numeric monster above), you might harness date to do the work for you. To wit date -I => 2023-12-17 (alternatively, if you want a finer resolution): date -Iseconds => 2023-12-17T11:48:28+01:00 Now date can "read" those (option -d): date -d $(date -Iseconds) => Sun Dec 17 11:49:46 CET 2023 With all of this, you can do: d1=$(date -Iseconds) ; sleep 5 ; d2=$(date -Iseconds) echo "$d1 $d2" => 2023-12-17T11:51:43+01:00 2023-12-17T11:51:48+01:0 and now: echo $(( $(date -d"$d2" +"%s") - $(date -d"$d1" +"%s") )) => 5 ... the "%s" format indicator telling date to print "seconds since 1970-01-01". Instead of -Iseconds you can do -Ins. See the date man page for all the gory details. Me? I'd keep internal results always as "seconds since 1970-01-01" and only transform on display. Cheers -- t
signature.asc
Description: PGP signature
