Shell Programming and Scripting

I have a cron entry to deploy a website portal from a staging server to a series of production servers on a weekly basis.

On occasion, a random office worker who knows nothing about Linux let alone cron, will be tasked to update news picks on the staging server and then run a manual deployment to the production servers. So I threw together a quick PHP/JQuery script that will take the date and time chosen and insert a properly-formatted line into cron.

The trouble I'm having is finding a way to clean out the old one-run cron jobs. Rather than having the sys admin go in once in a while to clean out those old jobs, I'd like to have it deleted at the end of the run. It will take nearly an hour for the deployment to complete, so comparing the minutes passed will be enough.

What I want to do is using a bash script, read in a crontab line, find all lines with specific numbers for the date/time (no '*', ranges, multiples or '*/n'), and compare them to the current date. If in the past, delete the line.

Note there are lines that are comments or variable declarations, as well as the weekly deployment.

Any ideas?

Thanks,
Andrew

---------- Post updated at 01:04 PM ---------- Previous update was at 09:47 AM ----------

Nevermind, got it figured out. Bit of a hack but...

Code:

currYear=$(date '+%Y')
cronNow=$(date '+%Y-%m-%d %H:%M')
cronNowS=`date --date="$cronNow" +%s`
crontab -l > tempcron.txt
touch temp
while read -r line ; do
        #parse the line into an array by space
        IFS=' ' read -a cronJob <<< "$line"
        minute="${cronJob[0]}"
        hour="${cronJob[1]}"
        day="${cronJob[2]}"
        month="${cronJob[3]}"
        #if it's anything but numeric, it's not a single date...
        cronNumTest=$minute$hour$day$month
        if [[ $cronNumTest =~ ^[0-9]+$ ]]; then
                #numeric: convert to a date and compare to now.
                cronTime="$currYear-$month-$day $hour:$minute"
                cronTimeS=`date --date="$cronTime" +%s`
                if [[ $cronTimeS -gt $cronNowS ]]; then
                        echo "$line" >> temp
                fi
        else
                #leave the CONST declarations, comments and permanent cron jobs intact...
                echo "$line" >> temp
        fi
done < "tempcron.txt"
mv temp tempcron.txt
crontab < tempcron.txt
rm tempcron.txt

If anyone has a shorter, cleaner solution, I'd appreciate seeing your example code.

Cheers,
Andrew

Every cron line fires at least once in 28 years. Just look for months not 0-5 months in the future?

I don't quite get it: if you want to run a job exactly once, why do you (mis-)use cron instead of using at? The effort is the same, the format is even easier and you don't need any crontab-gymnastics afterwards.

I hope this helps.

bakunin