unitproc/bkdstcountdown

   1 #!/bin/bash
   2
   3 # Date: 2020-02-13T23:14Z; baltakatei>
   4
   5 # Description: This script outputs days until the next time zone
   6 # discontinuity using 'zdump' and 'date'.
   7
   8 #=================ADJUST ME=======================
   9 SCRIPT_TZ="America/Los_Angeles" # Timezone to check for discontinuities
  10 #=================================================
  11
  12 echoerr() {
  13     echo "$@" 1>&2;
  14 }
  15
  16 # Declare variables
  17 declare -a datesDiscontArray #array
  18
  19 SCRIPT_YEAR=$(date +%Y)
  20 SCRIPT_YEAR_NEXT=$(( $(date +%Y) + 1))
  21 SCRIPT_RUN_DATE_SECONDS=$(date +%s)
  22
  23 # Save zdump output for SCRIPT_YEAR (for how multiline data saved in variable, see https://stackoverflow.com/a/613580 )
  24 datesDiscont="$(zdump -c $SCRIPT_YEAR_NEXT -v $SCRIPT_TZ | grep $SCRIPT_YEAR |  awk '{ print $2 " " $3 " " $4 " " $5 " " $6 " " $7 }'; echo)"
  25 if [ -z "$datesDiscont" ]; then
  26     echo "No time discontinuity this year."
  27     exit 1
  28 fi
  29
  30 ###echoerr "datesDiscont:--""$datesDiscont""--"
  31
  32 # Count lines in datesDiscont (for counting lines in a variable, see https://stackoverflow.com/a/6314682 )
  33 #datesDiscontLineCount=$(echo "$datesDiscont" | wc -l)
  34
  35 # Convert datesDiscont into array (for how to process each line in a multiline variable, see https://superuser.com/a/284226 )
  36 while IFS= read -r line; do
  37     #echo "$line"
  38     #datesDiscontArray+="$line"
  39     datesDiscontArray+=($(date --date="$line" +%s))
  40     #echo ${datesDiscontArray[-1]}
  41 done <<< "$datesDiscont"
  42 #echoerr ${datesDiscontArray[@]}
  43
  44 # Sort datesDiscontArray (see https://stackoverflow.com/a/11789688 )
  45 IFS=$'\n' datesDiscontArray=($(sort <<<"${datesDiscontArray[*]}"))
  46 unset IFS
  47
  48 # Get earliest date in datesDiscontArray that isn't in the past.
  49 for discontinuityDate in "${datesDiscontArray[@]}"; do
  50     ###echoerr "Discontinuity date (seconds):"$discontinuityDate
  51     ###echoerr "SCRIPT_RUN_DATE_SECONDS     :"$SCRIPT_RUN_DATE_SECONDS
  52     if [ $discontinuityDate -gt $SCRIPT_RUN_DATE_SECONDS ]; then
  53         ###echoerr "DEBUG:Date in future."
  54         nextDiscontDate="$discontinuityDate"
  55         break
  56     fi
  57 done
  58
  59 echo $(( ( $nextDiscontDate - $SCRIPT_RUN_DATE_SECONDS )/86400 ))" days" # Days until next discontinuity date