Problem executing scripts from cron.

glore2002 · 10-01-2009, 05:47 AM

I am adding the following scripts to cron via crontab -e (as user)

Quote:

# m h dom mon dow command
10 6 1 oct thu /home/lacalga/bin/tapecorto 12 prueba 00:10:00 >> dev/null 2>&1

25 6 1 oct thu sudo /sbin/shutdown -h now >> /dev/null 2>&1

The first one is to record tv. I've added dev/null 2>&1 at the end. No too clear why but without it, it records only a few seconds.

The second script is (as you should already noticed) to turn off my computer at 6:25 am. It doesn't work (with or without dev/null 2>&1). I am surely forgetting something important. Could you please tell me what is it?

Thanks,

bradvan · 10-01-2009, 05:57 AM

The crontab has it's own path setup. It may not know where to find sudo. It's always best to put the full path in for all objects. As for your first entry, I'm not familiar with the application. Does it work from the command line?

repo · 10-01-2009, 06:02 AM

The user doesn't has permission to execute shutdown.
Add the crontab as root

Code:

su
crontab -e

Or give the user permissions to shutdown the system.

catkin · 10-01-2009, 06:03 AM

Quote:

Originally Posted by glore2002

The first one is to record tv. I've added dev/null 2>&1 at the end. No too clear why but without it, it records only a few seconds.

The second script is (as you should already noticed) to turn off my computer at 6:25 am. It doesn't work (with or without dev/null 2>&1). I am surely forgetting something important. Could you please tell me what is it?

The first needs >> dev/null 2>&1 because it is producing some output to terminal which cron has no place to send (because there is no terminal for the job) so it stops running the executable (script?). By redirecting all output to "nowhere" you ensure there is no output to terminal and cron does not stop the job. You may prefer to send output to a log file instead of /dev/null, in case there are some error messages you want to see to solve a problem.

When you run the other command at a terminal, do you have to enter a password? If not, then try changing sudo to /usr/bin/sudo.

glore2002 · 10-01-2009, 08:00 AM

Quote:

Originally Posted by catkin

The first needs >> dev/null 2>&1 because it is producing some output to terminal which cron has no place to send (because there is no terminal for the job) so it stops running the executable (script?). By redirecting all output to "nowhere" you ensure there is no output to terminal and cron does not stop the job. You may prefer to send output to a log file instead of /dev/null, in case there are some error messages you want to see to solve a problem.

When you run the other command at a terminal, do you have to enter a password? If not, then try changing sudo to /usr/bin/sudo.

What if I want to send (as you said) the output to a log file? How should I do that? What should I add instead of /dev/null?

Regarding to sudo, I will try writing full path instead of just sudo. By the way How do I assign root right to lacalga user?

Thanks to all of you for the help provided. I appreciate it!

catkin · 10-01-2009, 09:03 AM

Quote:

Originally Posted by glore2002

What if I want to send (as you said) the output to a log file? How should I do that? What should I add instead of /dev/null?

Regarding to sudo, I will try writing full path instead of just sudo. By the way How do I assign root right to lacalga user?

Code:

10 6 1 oct thu /home/lacalga/bin/tapecorto 12 prueba 00:10:00 >> <my log file name> 2>&1

where <my log file name> is whatever you want, perhaps /home/prueba/tapecorto.log

Dunno about sudo. Never knowingly use it. Plenty of stuff out there to netsearch for or you could try reading the sudo (and sudoers?) man page. Why don't you just run the command root's crontab? Then you wouldn't need sudo.

Generally squeaking you dinna wanna have root privileges except when you want them (IYSWIM) because you (or malfeasing programs that have sneaked into running with your privileges) can do a lot of harm that way.

glore2002 · 10-01-2009, 10:40 AM

Quote:

Originally Posted by catkin

Code:

10 6 1 oct thu /home/lacalga/bin/tapecorto 12 prueba 00:10:00 >> <my log file name> 2>&1

where <my log file name> is whatever you want, perhaps /home/prueba/tapecorto.log

Dunno about sudo. Never knowingly use it. Plenty of stuff out there to netsearch for or you could try reading the sudo (and sudoers?) man page. Why don't you just run the command root's crontab? Then you wouldn't need sudo.

Generally squeaking you dinna wanna have root privileges except when you want them (IYSWIM) because you (or malfeasing programs that have sneaked into running with your privileges) can do a lot of harm that way.

Very clear again. I share your opinion about root privileges. I will create the task as root.

Thanks again,