Martin,
This script should give you enough information to figure out how to do what
you want. It is not intended to be used as written; it doesn't do any
syntax checking.
Throw the script in a file, mark it executable, and pass the date you're
looking, in the same format as third friday of july, on the command line.
(e.g. ./some_file third friday of july)
#!/bin/sh
# Parse input
week=$1
weekday=$2
month=$4
case "$week" in
[Ff][Ii][Rr][Ss][Tt])
skip_weeks=0;
;;
[Ss][Ee][Cc][Oo][Nn][Dd])
skip_weeks=1;
;;
[Tt][Hh][Ii][Rr][Dd])
skip_weeks=2;
;;
[Ff][Oo][Uu][Rr][Tt][Hh])
skip_weeks=3;
;;
[Ff][Ii][Ff][Tt][Hh])
skip_weeks=4;
;;
esac
# Convert the weekday to a number ( 1 = Monday, 2 = Tuesday, ... )
weekday_no=$( date -d "$weekday" +%u )
# Qualify the month with a year and a day (the first) for
# illustrative purposes
first_of_month=$( date -I -d "${month} 1" )
# Now that we're done formating the input, these three lines do the
# real work.
# Find the weekday number of the first day of the month
# (again 1 = Monday, ... )
first_weekday_no=$( date -d "${first_of_month} ${skip_weeks} weeks" +%u )
# Do some math; difference between desired weekdays + 7 then mod by 7.
let skip_days=(7+weekday_no-first_weekday_no)%7
# Use date to print the date. You can format if desired.
date -d "${first_of_month} ${skip_weeks} weeks ${skip_days} days"
Doug Knight
Martin Klier wrote:
> Hi Linux Admins,
>
> is there a command to get something like "thrid friday of july" or "second
> wednesday each month"? I crossread the manuals for date and gcal, but it
> seems to be impossible. Next thing I found was gcal, with
> "--period-of-fixed-dates", but I have not been able to get useful results,
> and
> date -d "35 tuesday" (35th tuesday of a year), but I have not been able to
> limit it to months nor selecting the year (by the way, I do not need it).
>
> Has somebody experience with this one, and can you give me a hint where to
> look, or even an example?
>
> Thanks a lot in advance,
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