Re: [Linux_Egypt] i need shell acount !
- hi ya gama3aa,techomena isp i giving a shell account ...( egypt )howaa mawgood 3andenaa fee alexandria mesh 3aref ezaa kaan mawgood fee cairo wala la2kaman if you get a shared hosting account you can get a telnet access ...thanksislam el-azazy----- Original Message -----From: Alaa The GreatSent: Sunday, December 30, 2001 8:03 PMSubject: Re: [Linux_Egypt] i need shell acount !On Sun, 30 Dec 2001 03:00:22 -0800 (PST)
walid farouk <walid_farouk@...> wrote:
first of all I think the question sa6ry was asking was if we knew of any
ISP that provides shell acounts that let you run scripts while you'ren't
logged on (so you tell it you want these files downloaded, and you
disconnect, next day you download these files directly from your ISP to
your PC which takes less time).
> I know someone do it using a cron job.
> I don't know exactly what it is and how it works, but
> i think it make the Unix system execute a script or
> some scripts at a specified time.
yes exactly, cron is a tool that lets you specify jobs (could be command or scripts or whatever you like) in the file /etc/crontab
these commands will then be excuted according to a particular schedule (for instance every wednesday at 3:00 do a fsck, or every day at 8:00 play alarm.au, or even every 1st of jan say happy new year).
usually your crontab file will look like this:-
----- begin /etc/crontab file
01 * * * * root run-parts /etc/cron.hourly
02 4 * * * root run-parts /etc/cron.daily
22 4 * * 0 root run-parts /etc/cron.weekly
42 4 1 * * root run-parts /etc/cron.monthly
------ end /etc/crontab file
the first few lines are envirement variables and explain themselve
the run-parts is the important one
its obvious here that my system has four seperate tables for hourly, daily, weekly and monthly jobs
the numbers in the begining stand for
minute hour dayofmonth month dayofweek
then comes the user that will be used to run these jobs
and last field is the job (run-parts is a small tool that runs scripts by guessing which interpreter to use, so run-parts foo is basically equivelant to bash foo, or python foo or whatever).
so the hourly jobs are excuted on the first minute of every hour in every day in every month (could be fetchmail or sendmail etc.)
the daily jobs are excuted on the second minute of the fourth hour of every day in every month (a fortune maybe or a some check on your logs)
the monthly jobs are excuted on the 22nd minute of the 4th hour of anyday in anymonth that is a sunday(thats what the last 0 stands for)
(and this could be a fsck or a cleanup of your tmp dirs)
and lastly the monthly jobs are excuted on the 42nd minute of the 4th hour of the first day of any month (a backup to your /etc maybe)
and the happy new year seting will look like this
01 0 1 1 * alaa echo 'happy new year'
02 0 1 1 * alaa mail -s 'happy new year' friends<greetings.txt
so on the first minute at midnight on the first of jan write happy new year on the console
and on the 2nd minute of the same date send an email to all friends with the subject 'happy new year' and have the content of greetings.txt as the message body.
however cron is of limited use to your usual home user since it assumes your pc is on all the time so if I don't open my pc on 1st of jan until the morning (which is probably what will happen) my friends will not get a message from me and my computer will not greet me thus ruining the whole year from day one.
a tool that would be more useful is anacron, it doesn't assume your computer will be on all the time but rather you have to describe a frequency for this particular job (like I want this done once a month and that done once a year).
however anacron is a totaly different story.
both cron and anacron aren useful if you like your command/script to run only once (not periodicaly) in this case you use the tool at
if anyone one is interested in learning at or anacron just say so and I'll tell send another tutorial on how they work.
meanwhile to to read the cron and crontab man pages
man 5 crontab
you may want to check the man pages for anacron and at too
your GNU/Linux system comes with a whole lot of docs and manuals try to read as many of them as you can.
Regret any inconvinience
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Happy New Year All
May god bless your new year and make it more beautiful than the one before ;)
- -- Katoob Main Developer
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FIRST make it run, THEN make it run fast "Brian Kernighan".
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