examples/scripts.v2/cal2day.bash

   1 #!/bin/bash
   2 # cal2day - "parse" appropriate calendar output to match date number
   3 #           with day name.
   4 #
   5 # usage: cal2day month day [year]
   6 #
   7 # ORIGINAL *TAG:33239 3:Dec 9 1997:0755:sh.d/cal2day:
   8 #
   9 # Obtained from usenet
  10 #
  11 # Converted to bash v2 syntax by Chet Ramey <chet@po.cwru.edu>
  12
  13 #1 PARSE OPTIONS
  14 while getopts :dls _inst
  15 do      case $_inst in
  16         (d)     format='%1d%.0s\n' ;;           # 0, 1, ..., 7
  17         (l)     format='%0.s%-s\n' ;;           # Sunday, Monday, ..., Saturday
  18         (s)     format='%0.s%-.3s\n' ;;         # Sun, Mon, ..., Sat
  19         esac
  20 done
  21 shift $((OPTIND-1))
  22
  23 #2 PARAMETER VALUES
  24 ((!$#)) && set -- $(date '+%m %d')
  25 : ${format:='%0.s%-.3s\n'}
  26 : ${1:?missing month parameter [1-12]}
  27 : ${2:?missing day parameter [1-31]}
  28
  29 #3 CALCULATE DAY-OF-WEEK FROM DATE
  30 cal $1 ${3:-$(date +%Y)} | gawk -FX '
  31 BEGIN   { day="Sunday   Monday   Tuesday  WednesdayThursday Friday   Saturday"
  32           sub(/^0/, "", daynum)
  33           dayre="(^| )" daynum "( |$)"
  34         }
  35 #NR==2  { print length($0) }
  36 NR==1 || NR==2 \
  37         { next }
  38 dayre   { if (match($0, dayre))
  39           {     #print RSTART, RLENGTH, substr($0, RSTART, RLENGTH)
  40                 if (daynum<=9 || RSTART==1) RSTART-=1
  41                 exit
  42           }
  43         }
  44 END     { # 20/21 char width assumed
  45           printf format, RSTART/3, substr(day, RSTART*3+1, 9)
  46         }
  47 ' daynum=$2 format=$format -
  48
  49 exit 0