Generally, there are usually lots of functional and non-functional ways to do something. That non-functional ways are to be avoided is obvious, but less obvious is that some functional ways should be avoided too.

If you know that going from A to B in a direct way means having to pass the traffic jam at C this makes the direct rooute less desirable and maybe the route over D E and F better overall, despite the route over C still being "functional" as it finally will get you where you want to go.

No problem. Here is how i would do it:

Code:

#! /bin/bash

pCheckDOW ()
{
typeset chDOW="${1:0:3}"

if [ "${chDOW}" != "Sun" ] ; then
     return 1
fi

return 0
}



pCheckAttempts ()
{
typeset fLog="${1}"
typeset iCurrDay="${2}"
typeset iNrOfAttempts=0
typeset iMaxAttempts=3
                                                     # clear log from old entries
grep "$iCurrDay" "$fLog" > "${fLog}.tmp"
mv "${fLog}.tmp" "${fLog}"
echo "$iCurrDay" >> "$fLog"

iNrOfAttempts=$(wc -l "$fLog")
if [ $iNrOfAttempts -gt $iMaxAttempts] ; then
     echo "Error: $iNrOfAttempts exceeds set maximum of $iMaxAttempts"
     return 1
fi
return 0
}





# ------- main
typeset chDate="$(date +'%a %d')"
typeset fAttemptsLog="/tmp/attempts.log"

if ! pCheckDOW "${chDate:0:3}" ; then
     echo "Error: This is the wrong day of week to run ${0}." >&2
     exit 1
fi

if ! pCheckAttempts "$fAttemptsLog" "${chDate:4:2}" ; then
     echo "Error: Attempts to run are already exhausted."
     exit 2
fi

# .... do lots of stuff here

exit 0

Notice, that illegitimate attempts on non-Sundays will not affect the attempts-log because the script terminates before even checking that.

The script relies on the fact that two consecutive Sundays will not have the same day of month. It could be fooled, though, if sufficient time between two attempts to run it would pass so that Sunday falls on the same day of month than the Sunday of the last attempt.

I hope this helps.

bakunin