I have used 'sudo crontab -e' to put following line:

0 * * * * for((i=0;i<4;i++)) do aplay up.wav; sleep 5s; done


I want it to play this wave file 4 times at every hour. But it is not working. Please help.

ouch, nasty. Put the commands into a script, make sure that script works and then run the script from cron. For hourly jobs you should have a directory /etc/cron.hourly which you can just drop files in and they will then be executed hourly automatically.

Anything I need to do if the script file has to be with an argument, eg: 'myscript.sh 15'. Do I enclose the full command in quotes or double quotes?

no, you don't or it will take the entire string as an executable name and choke.

0 * * * * /bin/bash /full/path/to/my/script.sh 12345

or for /etc/crontab:

0 * * * * root /bin/bash /full/path/to/my/script.sh 12345

Thanks. But why did you find the the small script on command line so "ouch, nasty"? Also what is difference between modifying cron using 'sudo crontab -e' and through /etc/crontab ?

I find running stuff in crontab can be confusing, and it's easy to be unclear where you are starting from. Your code is bash / sh but cron doesn't execute code within a shell, it's just directly run without a fully formed environment to utilize. So by saying "run this script with bash" as the cron instruction you can quickly get back to a common point that you can also get to from a normal login shell. Just much simpler that way.

as root, crontab -e will edit the root users crontab file in /var/spool/cron (or similar). this is different to the system crontab file in /etc/crontab. Personally I don't ever use roots crontab file, as it's so easy to forget about, and isn't anything root wants to do actually being done for the system as a whole, not him (or her) self?

Following crontab entry is also not working:

where chimer.sh is as follows:

what user is this? what crontab is it in? I wouldn't think it relevant, but I would replace ~ with the real path, for clarity if nothing else.

I have replaced ~ with full pathname which is /home/home/ here.

I am not sure about "what crontab". I am using command 'sudo crontab -e' and modifying the commands. I am using ubuntu 10.04LTS. And I find the changes are incorporated in /var/spool/cron/crontabs/root file.

Thanks for helping me.

Ahh, I meant /etc/crontab vs crontab -e as the files are a different format. Does the script itself work if you manually execute the exact same cron command (including the bash bit) ?

The script itself works very well. I have not tried /etc/crontab but my problem is solved after I used the command 'crontab -e' (without sudo). Now it is working well. Earlier it must have been going to the root's crontab and I am not working as root most of the time.


@acid_kewpie: Thanks for your help. I realize that you have great experience in linux with almost 39000 posts here. I see that gentoo is your top distribution. How difficult is gentoo for an ubuntu user to migrate to. Is software installation and dependency resolution major problems there? If you want I will put this question as a separate thread.

it shoudl be a different thread really, but Gentoo is pretty easy really. I've not used it for a while, but the installation guide was always pretty simply, as long as you follow the right steps. It works differently low down to ubuntu, or any other distro I've used, but it's certainly worth a go.

Just one last question:
The /etc/crontab files looks very similar, only I would need to enter the user name also:
Please confirm.

yes, but who calls a user "home"??

Haha! I created the user home for my home computer, without realizing that all users are in /home directory in linux. So my home directory is /home/home. However, I have not had any problems with any programs, except one which refused to save data in 'home' directory!