Convert seconds to hours, minutes, seconds

Use date, converted to UTC:

$ date -d@36 -u +%H:%M:%S
00:00:36
$ date -d@1036 -u +%H:%M:%S
00:17:16
$ date -d@12345 -u +%H:%M:%S
03:25:45

The limitation is the hours will loop at 23, but that doesn't matter for most use cases where you want a one-liner.

On macOS, run brew install coreutils and replace date with gdate

Simple one-liner

$ secs=236521
$ printf '%dh:%dm:%ds\n' $((secs/3600)) $((secs%3600/60)) $((secs%60))
65h:42m:1s

With leading zeroes

$ secs=236521
$ printf '%02dh:%02dm:%02ds\n' $((secs/3600)) $((secs%3600/60)) $((secs%60))
65h:42m:01s

With days

$ secs=236521
$ printf '%dd:%dh:%dm:%ds\n' $((secs/86400)) $((secs%86400/3600)) $((secs%3600/60)) \
  $((secs%60))
2d:17h:42m:1s

With nanoseconds

$ secs=21218.6474912
$ printf '%02dh:%02dm:%02fs\n' $(echo -e "$secs/3600\n$secs%3600/60\n$secs%60"| bc)
05h:53m:38.647491s

Based on https://stackoverflow.com/a/28451379/188159 but edit got rejected.

#!/bin/sh

convertsecs() {
 ((h=${1}/3600))
 ((m=(${1}%3600)/60))
 ((s=${1}%60))
 printf "%02d:%02d:%02d\n" $h $m $s
}
TIME1="36"
TIME2="1036"
TIME3="91925"

echo $(convertsecs $TIME1)
echo $(convertsecs $TIME2)
echo $(convertsecs $TIME3)

For float seconds:

convertsecs() {
 h=$(bc <<< "${1}/3600")
 m=$(bc <<< "(${1}%3600)/60")
 s=$(bc <<< "${1}%60")
 printf "%02d:%02d:%05.2f\n" $h $m $s
}