Tip: Run a script after FAI install

[John G Heim]

So I had this problem. I want to configure certain users to have sudo on 
the workstations I manage. Problem we do ldap authenticaition -- so the 
users don't exist during the install. I can easily write an fai script 
to do an adduser but it doesn't work because the user doesn't exist 
during the install. What I needed to do is to run a script once after 
the system reboots into the newly installed operating system. I thought 
about putting a script on there that would run at boot time and delete 
itself. But that's ugly and failure prone. But I came up with a solution 
that is much more reliable and flexible.

1. Create a crontab file to be copied to the target system during the 
install. For example, during my fai installs, I create a class called 
INSTALL. So I created a crontab file 
/srv/fai/config/files/etc/crontab/INSTALL.

Put a command like this in this file:

@reboot root fai --class/dev/null=POSTINST softupdate

2. Add an fcopy command to one of your installation scripts to copy the 
crontab file:

fcopy -Bi /etc/crontab

3. Create another, normal crontab file without the above line and call 
it POSTINST or whatever you called the class in the first crontab. In 
this example, it would be /srv/fai/config/files/etc/crontab/POSTINST.

4. in your fai script space, create a directory called POSTINST

mkdir /srv/fai/config/scripts/POSTINST

5. Put a script in there to install the normal crontab file

fcopy -Bi /etc/crontab

6. Put scripts to do whatever else you want into that same directory. 
These scripts will be run just once when the system reboots after the 
original fai install. The target machine will look completely normal and 
there won't be any extra programs/scripts on it (unless you count fai 
itself).

Verstehst du?

-- 
--
John G. Heim; jheim at math.wisc.edu; sip://jheim@sip.linphone.org