Shell Programming and Scripting

Hi everyone,

I'm a newbie to Linux scripting. I've been reading this forum for the last 6 hours trying to figure out the crontab and mail commands for the first time. I get to the point of successful copying and mailing. My question is how do I delete a specific task in the crontab queue without using crontab -r or without using vi editor from crontab -e, and then send me an email confirmation?

Below is a portion of my script:
-------------------------------------------------
#!/bin/bash

if test -f $file
then
# test if file exists and notify via email
echo "file already exists. Don't need to copy" | mail -s "file exists" $mail_user

else
echo "file does not exist ... starting crontab copy every half an hour."
echo "*/30 * * * * cp /tmp/file1 /tmp/file2 >> /tmp/file3

# Start the crontab
crontab file3
rm file3
fi

------------------------------------------------


Currently, this is what I have in my crontab queue (crontab -l):
*/30 * * * * cp /tmp/name1 /tmp/name2
*/30 * * * * cp /tmp/file1 /tmp/file2
*/30 * * * * cp /tmp/name1 /tmp/name2
*/30 * * * * cp /tmp/name1 /tmp/name2

How do I delete just one line (the second line from above list) from the crontab queue?
*/30 * * * * cp /tmp/file1 /tmp/file2

Again, I prefer not to use crontab -r because that would delete everything. Also I prefer not to use crontab -e and then delete just that line with vi editor, because I'm trying to automate this entire process.

After that line is deleted from the crontab queue, then send me an email saying that "File2 has been copied sucessfully."

If anyone has any suggestions or solutions, I would be greatly appreciated Thanks!

Well, it has been a few days since I posted this thread. So far are there are 36 viewers and 0 replies This must be a challenging one.

While waiting for a solution, I've found a "not so clean" way to delete a specific task in the crontab queue.

crontab -l > filename_list
sed -e '/file/d' filename_list > filename_queue
crontab filename_queue

The above 3 codes: First, get the queue list. Second, remove a specific line or lines from this list. Third, put the list back into queue.

crontab -e and run an ed script under vi?

crontabs are physically located in /var/spool/cron. All of the manuals I have ever read have this warning:- DO NOT edit those files directly Usually in bold type.

- which is your only other choice. If you are just hacking your own desktop system and like rebuilding the OS from scratch, try writing a sed or awk script to edit those files automatically.

This is probably why there have been no answers - there are no good answers except 'use crontab'.

But editing the files directly worked well with me in Solaris 10 Boxes

Code:

for i in hostname1 hostname2 hostname3
do
echo Modifying in $i
remsh $i "cp -p /var/spool/cron/crontabs/root /var/spool/cron/crontabs/root.bkp1" # Taking bkp
remsh $i "grep -v  file1 /var/spool/cron/crontabs/root > /var/spool/cron/crontabs/root.tmp" # Removing the entry
remsh $i "echo '<if any new entry to be made.....>' >> /var/spool/cron/crontabs/root.tmp" # Optional
remsh $i "cat /var/spool/cron/crontabs/root.tmp > /var/spool/cron/crontabs/root" # Modifying the original crontab
done