creating a cron(tab) scheduled thing

student04 · 12-26-2004, 07:35 PM

Hey,

I've already searched the Tutorials, and this forum for a thread on this, but haven't found one. How do you add a thing (I don't know what to call it) to cron so that I can specify it to run a program at 2AM, AND how to terminate it at 9AM. I know you can use ulimit to specify the amount of time a process can run from that terminal, but I'd like it to run without my having to tell it to (thus cron). man cron and man crontab don't say much...

Thanks

slakmagik · 12-26-2004, 08:06 PM

Interesting. Probably an elegant way to do it, but couldn't you just schedule it to run at 2 and schedule it to be killed at 9?
* 2 * * * foo
* 9 * * * killall foo

Might help to say which command you want to run.

student04 · 12-26-2004, 08:40 PM

I want to run the foldingathome.exe (don't worry, it works somehow - it's the "official linux" client) file in the directory /home/alex/folding@home/ simply using dot-slash (./) to run it. But i have to be IN that directory to run it, otherwise because it needs to load the configuration files... and.. somehow it doesn't do it when you type the full path from another directory. This program is completely command-line based and does not require root priviledges. I was thinking I could write a *simple* script to run it; one that just cd's into the folder and runs it.

The thing is, I've never used cron/crontab before

... all i know is that it is like a scheduler that performs actions at certain times and/or intervals.

Oh, and it (foldingathome.exe) doesn't have the luxury of so many options in it's configuration file to let it run at a certain time, and stop later.

Code:

[alex@localhost alex]$ cat folding@home/client.cfg
[settings]
username=amerritt
team=11534
asknet=no
machineid=1
local=1

[http]
active=no
host=localhost
port=8080

[alex@localhost alex]$

That's it.

Is cron difficult to implement?

slakmagik · 12-26-2004, 08:49 PM

Ah. I see. Sort of.

Yeah - do a 'crontab -e' and you edit the file and schedule programs. Not familiar with folding@home (in the sense of never having used it) but it's strange it would have to be run from a particular directory. Some programs look for configs in particular places, but usually have a command line option to tell them to look in alternate locations. You can schedule scripts to be run, so I suppose you could write a one-liner about 'cd /to/dir && folding@home' or something. Makes sense why you'd want to start and stop it at particular times, though. I don't think a 'killall' would present a problem. A last thing to check is whether the program can sort of schedule itself. Be a nice feature to have if it doesn't.

-- Oops. I was answering before your edit. That answers my last question.

Cron can be tricky with some things but it's pretty simple generally. You just have fields where you set the times and the commands, with '*' standing for 'all slots'.

Like part of mine is

Code:

#MIN HOUR DAY MONTH DAYOFWEEK COMMAND
10 15 * * * /home/j/sbin/slackchange

So at 3:10PM every day, it runs that script.

The only thing to do is export VISUAL=your-favorite-editor and run 'crontab -e', like I say.

student04 · 12-26-2004, 10:08 PM

Awesome! The script didn't work... but the one command line thing did the job, and so did killall.

Thanks a lot digiot

I owe you one

Just one more question.. will it still run even if i am not logged onto my computer?

slakmagik · 12-26-2004, 10:18 PM

No problem. Glad it's working.

As long as the machine's running, cron should.