| 1 | #!/bin/bash |
| 2 | # Desc: Template to report seconds until beginning of next day |
| 3 | # Author: Steven Baltaktei Sandoval; License: GPLv3+ |
| 4 | |
| 5 | #==BEGIN Define script parameters== |
| 6 | #===BEGIN Declare local script functions=== |
| 7 | yell() { echo "$0: $*" >&2; } # Yell, Die, Try Three-Fingered Claw technique; # Ref/Attrib: https://stackoverflow.com/a/25515370 |
| 8 | die() { yell "$*"; exit 111; } |
| 9 | try() { "$@" || die "cannot $*"; } |
| 10 | timeUntilNextDay(){ |
| 11 | # Desc: Report seconds until next day. |
| 12 | # Output: stdout: integer seconds until next day |
| 13 | # Output: exit code 0 if stdout > 0; 1 if stdout = 0; 2 if stdout < 0 |
| 14 | # Usage: timeUntilNextDay |
| 15 | # Usage: if ! myTTL="$(timeUntilNextDay)"; then yell "ERROR in if statement"; exit 1; fi |
| 16 | local returnState TIME_CURRENT TIME_NEXT_DAY SECONDS_UNTIL_NEXT_DAY |
| 17 | TIME_CURRENT="$(date --iso-8601=seconds)" ; # Produce `date`-parsable current timestamp with resolution of 1 second. |
| 18 | TIME_NEXT_DAY="$(date -d "$TIME_CURRENT next day" --iso-8601=date)"; # Produce timestamp of beginning of tomorrow with resolution of 1 second. |
| 19 | SECONDS_UNTIL_NEXT_DAY="$(( $(date +%s -d "$TIME_NEXT_DAY") - $(date +%s -d "$TIME_CURRENT") ))" ; # Calculate seconds until closest future midnight (res. 1 second). |
| 20 | if [[ "$SECONDS_UNTIL_NEXT_DAY" -gt 0 ]]; then |
| 21 | returnState="true"; |
| 22 | elif [[ "$SECONDS_UNTIL_NEXT_DAY" -eq 0 ]]; then |
| 23 | returnState="WARNING_ZERO"; |
| 24 | yell "WARNING:Reported time until next day exactly zero."; |
| 25 | elif [[ "$SECONDS_UNTIL_NEXT_DAY" -lt 0 ]]; then |
| 26 | returnState="WARNING_NEGATIVE"; |
| 27 | yell "WARNING:Reported time until next day is negative."; |
| 28 | fi |
| 29 | |
| 30 | try echo "$SECONDS_UNTIL_NEXT_DAY"; # Report |
| 31 | |
| 32 | #===Determine function return code=== |
| 33 | if [[ "$returnState" = "true" ]]; then |
| 34 | return 0; |
| 35 | elif [[ "$returnState" = "WARNING_ZERO" ]]; then |
| 36 | return 1; |
| 37 | elif [[ "$returnState" = "WARNING_NEGATIVE" ]]; then |
| 38 | return 2; |
| 39 | fi |
| 40 | } # Report seconds until next day |
| 41 | #===END Declare local script functions=== |
| 42 | #==END Define script parameters== |
| 43 | |
| 44 | |
| 45 | #==BEGIN sample code== |
| 46 | try echo "Time until next day (seconds):$(timeUntilNextDay)" # simple report |
| 47 | |
| 48 | if ! myTTL="$(timeUntilNextDay)"; then yell "ERROR in if statement for myTTL:$myTTL"; exit 1; fi # Use of exit code to exit early if time <= 0. |
| 49 | #==END sample code== |