| 1 | #!/bin/bash |
| 2 | |
| 3 | # Description: This script outputs days until the next time zone |
| 4 | # discontinuity using 'zdump' and 'date'. |
| 5 | |
| 6 | #=================ADJUST ME======================= |
| 7 | SCRIPT_TZ="America/Los_Angeles" # Timezone to check for discontinuities |
| 8 | #================================================= |
| 9 | |
| 10 | yell() { echo "$0: $*" >&2; } # Yell, Die, Try Three-Fingered Claw technique; # Ref/Attrib: https://stackoverflow.com/a/25515370 |
| 11 | die() { yell "$*"; exit 111; } |
| 12 | try() { "$@" || die "cannot $*"; } |
| 13 | |
| 14 | # Declare variables |
| 15 | declare -a datesDiscontArray #array |
| 16 | |
| 17 | SCRIPT_YEAR=$(date +%Y) |
| 18 | SCRIPT_YEAR_NEXT=$(( $(date +%Y) + 1)) |
| 19 | SCRIPT_YEAR_NEXT2=$(( $(date +%Y) + 2)) |
| 20 | SCRIPT_RUN_DATE_SECONDS=$(date +%s) |
| 21 | |
| 22 | # Save zdump output for SCRIPT_YEAR (for how multiline data saved in variable, see https://stackoverflow.com/a/613580 ) |
| 23 | datesDiscont="$(zdump -c "$SCRIPT_YEAR","$SCRIPT_YEAR_NEXT2" -v $SCRIPT_TZ | grep "$SCRIPT_YEAR\|$SCRIPT_YEAR_NEXT" | awk '{ print $2 " " $3 " " $4 " " $5 " " $6 " " $7 }'; echo)" |
| 24 | if [ -z "$datesDiscont" ]; then |
| 25 | echo "No time discontinuity this year."; |
| 26 | exit 1; |
| 27 | fi; |
| 28 | |
| 29 | ###yell "DEBUG:datesDiscont----------"; |
| 30 | ###echo "$datesDiscont" 1>&2; |
| 31 | ###yell "DEBUG:-----------"; |
| 32 | |
| 33 | # Count lines in datesDiscont (for counting lines in a variable, see https://stackoverflow.com/a/6314682 ) |
| 34 | #datesDiscontLineCount=$(echo "$datesDiscont" | wc -l) |
| 35 | |
| 36 | # Convert datesDiscont into array (for how to process each line in a multiline variable, see https://superuser.com/a/284226 ) |
| 37 | while IFS= read -r line; do |
| 38 | #echo "$line" |
| 39 | #datesDiscontArray+="$line" |
| 40 | datesDiscontArray+=($(date --date="$line" +%s)) |
| 41 | #echo ${datesDiscontArray[-1]} |
| 42 | done <<< "$datesDiscont" |
| 43 | #yell ${datesDiscontArray[@]} |
| 44 | |
| 45 | # Sort datesDiscontArray (see https://stackoverflow.com/a/11789688 ) |
| 46 | IFS=$'\n' datesDiscontArray=($(sort <<<"${datesDiscontArray[*]}")) |
| 47 | unset IFS |
| 48 | |
| 49 | ###yell "DEBUG:"; |
| 50 | ###yell "DEBUG:datesDiscontArray:"; |
| 51 | ###yell "${datesDiscontArray[@]}"; |
| 52 | ###yell "DEBUG:"; |
| 53 | |
| 54 | # Get earliest date in datesDiscontArray that isn't in the past. |
| 55 | for discontinuityDate in "${datesDiscontArray[@]}"; do |
| 56 | ###yell "DEBUG:Discontinuity date (seconds):"$discontinuityDate |
| 57 | ###yell "DEBUG:SCRIPT_RUN_DATE_SECONDS :"$SCRIPT_RUN_DATE_SECONDS |
| 58 | if [ $discontinuityDate -gt $SCRIPT_RUN_DATE_SECONDS ]; then |
| 59 | ###yell "DEBUG:Date in future." |
| 60 | nextDiscontDate="$discontinuityDate" |
| 61 | break |
| 62 | fi |
| 63 | done |
| 64 | |
| 65 | # Check that nextDiscontDate is not empty |
| 66 | if [ -z "$nextDiscontDate" ]; then |
| 67 | echo "ERROR:nextDiscontDate empty" |
| 68 | fi; |
| 69 | |
| 70 | |
| 71 | ###yell "DEBUG:nextDiscontDate:$nextDiscontDate"; |
| 72 | ###yell "DEBUG:SCRIPT_RUN_DATE_SECONDS:$SCRIPT_RUN_DATE_SECONDS"; |
| 73 | |
| 74 | echo $(( ( $nextDiscontDate - $SCRIPT_RUN_DATE_SECONDS )/86400 ))" days" # Days until next discontinuity date |