unitproc/bktemp-timeEpochNS

   1 #!/bin/bash
   2 # Desc: Get timestamp in nanoseconds
   3
   4 yell() { echo "$0: $*" >&2; }      #o Yell, Die, Try Three-Fingered Claw technique
   5 die() { yell "$*"; exit 111; }     #o Ref/Attrib: https://stackoverflow.com/a/25515370
   6 try() { "$@" || die "cannot $*"; } #o
   7 timeEpochNS() {
   8     # Desc: Get epoch nanoseconds
   9     # Usage: timeEpochNS
  10     # Version 0.2.3
  11     # Input: arg1: 'date'-parsable timestamp string (optional)
  12     # Output: Nanoseconds since 1970-01-01
  13     # Depends: date 8, cut 8, yell()
  14     # Ref/Attrib: Force base 10 Bash arith with '10#'. https://stackoverflow.com/a/24777667
  15     local argTime timeCurrent timeInput timeEpochFloat timeEpochInt
  16     local timeEpochNsFrac timeEpochNs
  17
  18     argTime="$1";
  19
  20     # Get Current Time
  21     timeCurrent="$(date --iso-8601=ns)"; # Produce `date`-parsable current timestamp with resolution of 1 nanosecond.
  22
  23     # Decide to parse current or supplied time
  24     ## Check if time argument empty
  25     if [[ -z "$argTime" ]]; then
  26         ## T: Time argument empty, use current time
  27         timeInput="$timeCurrent";
  28     else
  29         ## F: Time argument exists, validate time
  30         if date --date="$argTime" 1>/dev/null 2>&1; then
  31             ### T: Time argument is valid; use it
  32             timeInput="$argTime";
  33         else
  34             ### F: Time argument not valid; exit
  35             yell "ERROR:Invalid time argument supplied. Exiting."; exit 1;
  36         fi;
  37     fi;
  38     # Construct and deliver nanoseconds since 1970-01-01
  39     timeEpochFloat="$(date --date="$timeInput" +%s.%N)"; # Save ssss.NNNNNNNNN
  40     timeEpochInt="$(echo "$timeEpochFloat" | cut -d. -f1)"; # Get ssss
  41     timeEpochNsFrac="$(echo "$timeEpochFloat" | cut -d. -f2)"; # Get NNNNNNNNN
  42     timeEpochNs="$(( (10#"$timeEpochInt" * 10**9) + (10#"$timeEpochNsFrac") ))";
  43     echo "$timeEpochNs";
  44 } # Nanoseconds since 1970-01-01
  45
  46 #==BEGIN sample code==
  47 echo "It's been $(timeEpochNS) nanoseconds since 1970-01-01.";
  48 echo "It's been $(timeEpochNS "10 years ago") nanoseconds since 10 years ago.";
  49 echo "It's been $(timeEpochNS "2003-02-01T08:59:15-05:00") nanoseconds since contact lost with STS-107.";
  50 #==END sample code==
  51
  52 # Author: Steven Baltakatei Sandoval
  53 # License: GPLv3+