Crontab and Grep date problem... should be an easy fix

Kuro · 12-10-2009, 09:20 PM

Hey all.

I am having a problem getting my Crontab to work properly.

I'm using the bash shell.

I want to set up a crontab that emails me reports of login activity taken from my auth.log every night.

This is what I have in my crontab -l
I've read that crontab takes minimal environment so I added
/bin/grep and /bin/cat

Code:

# m h  dom mon dow   command

59 23 * * * /bin/cat /var/log/auth.log |/bin/grep "`date \"+%b %e\"`" |mail -s "Testing crontab" user@gmail.com

But I get nothing.
I've tested everything else, and the problem seems to be when I grep the date. This code works in the command line, but not in Crontab.

I can grep other things, but when I want this specific grep for a specific date, it doesn't work.

Is there something different with Crontab than the shell?

I have no problem if I put this command line into a script and using Crontab to run the script, but I'm just curious as to why crontab wont run the command straight.

Thanks for any input.

ghostdog74 · 12-10-2009, 09:54 PM

My suggestion to you: Put everything into a shell script. That way, if you want to add more code, you just edit the shell script and don't clutter up the crontab entries. Also, debugging is easier

Kuro · 12-10-2009, 10:29 PM

Quote:

Originally Posted by ghostdog74

My suggestion to you: Put everything into a shell script. That way, if you want to add more code, you just edit the shell script and don't clutter up the crontab entries. Also, debugging is easier

Yeah I know, it works with a script no problem... I just can't figure out why it wouldnt work in just crontab... its essentially the same thing, and the only thing I've read that may be different, is the environment.

chrism01 · 12-10-2009, 10:36 PM

Actually, ghostdog74 means put that into a script and call the script from cron. As he said, it's easier to amend.
Anyway, you prob need the full path the the 'date' cmd, its not a shell built-in.
On the Suse box I've got here, it's /bin/date. Try 'which date'.

Kuro · 12-10-2009, 10:46 PM

Quote:

Originally Posted by chrism01

Actually, ghostdog74 means put that into a script and call the script from cron. As he said, it's easier to amend.
Anyway, you prob need the full path the the 'date' cmd, its not a shell built-in.
On the Suse box I've got here, it's /bin/date. Try 'which date'.

I thought thats what he meant.

I have the script in a file in my /home/user/status.sh

My previous crontab setting if I did a crontab -l was

Code:

# m h  dom mon dow   command

18 21 * * * /home/user/status.sh

My status.sh was

Code:

#!/bin/sh

CurrentDate=$(date "+%b %e")
echo $CurrentDate

cat /var/log/auth.log |grep "${CurrentDate}" |sed '/CRON/d' > /home/user/$CurrentDate.log

cat /home/user/"$CurrentDate".log  |mail -s "Todays attempts" user@gmail.com

Good idea though. I never thought about date... My 'which date' revealed

/bin/date

If I were to use full path, would it be |/bin/grep "`/bin/date \"+%b %e\"`" ?

ghostdog74 · 12-10-2009, 10:54 PM

you can just export your PATH in your script

Code:

export PATH=/bin:$PATH

chrism01 · 12-11-2009, 01:44 AM

cron jobs don't login as you, so the $PATH (if any) will be the one set in the cron env. That's why you have to either specify a PATH list in full or use full paths to all cmds/files.
Of course, you could start by sourcing your home/you/.bashrc or .bash_profile to get your normal PATH settings first.