Formatting the date in unix to include suffix on day (st, nd, rd and th)

Question

How can I add the suffix on the day number of a unix date?

I'll explain. I have a TextMate bundle snippit that writes out today's date. It uses unix date and formatting. Here is the code:

`date +%A` `date +%d` `date +%B` `date +%Y`

It outputs:

Monday 22 March 2010

I would like to add the suffix to the day (st, nd, rd and th) like so:

Monday 22nd March 2010

As far as I can see, there is no native function in the unix date formatting, like there is in PHP (j). How would I achieve this in unix? A complicated regex on the day number?

Answer 1

I have something similar working on a Linux machine (Ubuntu 8.10). I don't think it will work with Solaris, the one machine I tested did not allow using a _ character following the % to avoid padding the field with a 0. The non-padding allows date to return 1 instead of 01 (01st doesn't look right versus 1st).

I use a shell function (again, your OS or shell version may not like the way I defined the function) named DaySuffix, then call that func as part of the date call. The func itself is fairly hacky, I'm sure there is a better way to do this but it works for me. Note the special cases for 11, 12, & 13 - you've got to love the English language!

#!/bin/sh

DaySuffix() {
    if [ "x`date +%-d | cut -c2`x" = "xx" ]
    then
        DayNum=`date +%-d`
    else
        DayNum=`date +%-d | cut -c2`
    fi

    CheckSpecialCase=`date +%-d`
    case $DayNum in
    0 )
      echo "th" ;;
    1 )
      if [ "$CheckSpecialCase" = "11" ]
      then
        echo "th"
      else
        echo "st"
      fi ;;
    2 )
      if [ "$CheckSpecialCase" = "12" ]
      then
        echo "th"
      else
        echo "nd"
      fi ;;
    3 )
      if [ "$CheckSpecialCase" = "13" ]
      then
        echo "th"
      else
        echo "rd"
      fi ;;
    [4-9] )
      echo "th" ;;
    * )
      return 1 ;;
    esac
}

# Using consolidated date command from chris_l
# Also using %-d instead of %d so it doesn't pad with 0's
date "+%A %-d`DaySuffix` %B %Y"