Unix help urgent help please!

**eblaster101** · 29th March 2005

hi,

i really really need help with some work i need to do really stuck in the mud here any help will be appreciated.

I have been asked to create a script which performs a action only when nobody is using the computer.

if you know how to do this can you please explain will be greatlly appreciated.

thanks

**/dev/null** · 29th March 2005

Try cron...?

**petecowie** · 30th March 2005

BTW: cron allows you to schedule jobs to run on a particular day, hour, minute, day, etc.
So set the program to run at a time you can guarantee no-one is on the system for example 3am, this way your script doesn't have to perform this check itself. Log in as root and type the command crontab -e this will allow you to edit roots cron (schedule) Just add another line to represent the program you want run. The five numbers on the line tell you cron when to run and represent minutes hours monthday month weekday and are following by command to run ls -l to a file at 5am everyday use the following
0 5 * * * ls -l > /tmp/filename

Hope this helps (and that I've got it right, it's been a while!)

Pete

**ShadowMoses** · 30th March 2005

as far as crontab entry's go I found this tool

http://htmlbasix.com/crontab.shtml

you put in what script and when you want it running and it generates the line you need to add to the crontab

not too sure how to get it to check and only run when others are online.

hope I helped in some way

Moses

**BertRoot** · 30th March 2005

What sort of computer? A UNIX server? A UNIX workstation? Cron would not be suitable for this sort of thing IMO? Can you clarify your requirement?

**eblaster101** · 30th March 2005

its a unix workstation mate

the computer has to chek when no one is on the server because its running on a unix server, which is being accessed all the time at random times. I think i have to use the command 'who' becasue who checks who is logged into unix

**/dev/null** · 30th March 2005

Well, lets say you were using the root account to run the script (or you have created a special account to do it) then you would have something like this:

Code:

#!/bin/bash
if who | grep -v "root" != ''
then
echo Cannot run script - other users logged in
exit 1
fi

#the rest of your script here

That is assuming the script can be initiated wen someone else is logged in, but if they are then it will not run fully, it will see that they are logged in and then terminate until the next time it is scheduled to run. You could even have it run say every 15 minutes, each time it would fail if there was someone logged in and then when it sees that no-one apart from root or your created account is logged in, it will run the script.
Hope tihs helps a little - you may get a bit better help in the linux section though because more unix users will look in there.