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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 |