user/bkdatediff

   1 #!/usr/bin/env bash
   2 # Desc: Get time difference two between date-parsable strings in seconds
   3 # Usage: bkdatediff [STRING] [STRING]
   4 # Example: bkdatediff "2023-01-10T08:36:42+00" "2023-01-10T12:30:13+00"
   5 # Version 0.0.1
   6
   7 yell() { echo "$0: $*" >&2; } # print script path and all args to stderr
   8 die() { yell "$*"; exit 111; } # same as yell() but non-zero exit status
   9 must() { "$@" || die "cannot $*"; } # runs args as command, reports args if command fails
  10 check_depends() {
  11     if ! command -v date 1>/dev/random 2>&1; then die "FATAL:Missing:date"; fi;
  12     return 0;
  13 }; # check dependencies
  14 show_usage() {
  15     cat <<'EOF'
  16   USAGE:
  17     bkdatediff [STRING1] [STRING2]
  18
  19   STRING1, STRING2
  20     `date` parsable strings. (i.e. variable STR in `date --date='$STR'`)
  21
  22   EXAMPLE:
  23     bkdatediff "2023-01-10T08:36:42+00" "2023-01-10T12:30:13+00"
  24 EOF
  25 };
  26 main() {
  27     local t1 t2;
  28     check_depends;
  29     # check args
  30     if [[ ! $# -eq 2 ]]; then show_usage; die "FATAL:Wrong number of args:$#"; fi;
  31
  32     # get unix epoch
  33     t1="$(must date --date="$1" +%s)";
  34     t2="$(must date --date="$2" +%s)";
  35
  36     # print diff in seconds
  37     printf "%s\n" "$((t2 - t1))";
  38 }; # main program
  39
  40 main "$@";