Shell Programming and Scripting

I am running AIX 5.3 with the default shell as ksh.

I would like to know how to run a cron job on this system the last calendar day of the month. I found an example, but, I'm not sure if it will work with AIX and ksh...

Code:

02 16 * * * [ $(date +%d) -eq $(echo $(cal) | awk '{print $NF}') ] && /home/user/job-eom.ksh

I also need to be able to run a job on every day except the last calendar of the month (actually a series of jobs, but, I assume I can adopt the syntax for multiple jobs).

So to summarize:

I would like to run the following jobs where specified EXCEPT on the LAST calendar day of the month.

Code:

50   21   *   *   *   /home/user/eod-job1.ksh
00   22   *   *   *   /home/user/eod-job2.ksh
10   22   *   *   0   /home/user/eod-job3.ksh
10   22   *   *   1-4   /home/user/eod-job4.ksh
00   23   *   *   1   /home/user/eod-job5.ksh
10   22   *   *   5-6   /home/user/eod-job6.ksh
50   4    *   *   *   /home/user/eod-job7.ksh

And I would like to run another job ON the LAST calendar day of the month, and probably a couple of others...

Code:

45   20   *   *   *   /home/user/eom-job1.ksh

I'm also fairly new at shell scripting, etc., especially ksh.

Code:

_days_in_month() ## USAGE: days_in_month [month [year]]
{
    case ${1#0} in
        9|4|6|11) _DAYS_IN_MONTH=30 ;; ## 30 days hath September...
        1|3|5|7|8|10|12) _DAYS_IN_MONTH=31 ;;
        2) is_leap_year ${2:-`date +%Y`} && _DAYS_IN_MONTH=29 || _DAYS_IN_MONTH=28 ;;
        *) return 5 ;;
    esac
}

is_leap_year() {
    [ $(( $1 % 4 ))   -eq 0 ] &&
    [ $(( $1 % 100 )) -ne 0 ] ||
    [ $(( $1 % 400 )) -eq 0 ]
}

eval "$( date +"year=%Y month=%m day=%d" )"

_days_in_month "$month" "$year"

if [ $_DAYS_IN_MONTH = ${day#0} ]
then
  : last day of month
else
  : not last day of month
fi

So...

Would I use this script for every job and just insert my ksh script (or my jobs) in the appropriate part of the if statement?

How might I combine this with cron?

Again I am fairly new at this whole thing...