Intercepting shutdown messges

José Alburquerque
Fri Aug 15 01:39:00 GMT 2008

José Alburquerque wrote:
> Hello.  This is my first post to this list and I simply have a general 
> question about pseudo terminals which I'm hoping can be answered on 
> this list!  As weird as it may sound, I'm trying to write a simple 
> program (in C naturally) to sort of "intercept" shutdown messages when 
> they are sent to terminals (I notice that all my open terminals 
> receive a "The system is going down in XXX minutes" when shutdown is 
> running).  To this end, I wrote a simple program that uses opentty() 
> to open a master/slave pseudo terminal pair.  I can read and print 
> data sent to the /dev/pts/* file sent to the slave using the master 
> file descriptor, but I'm sort of stuck because when shutdown runs, my 
> program doesn't read the shutdown messages.  Anyone have any 
> suggestions as to what I need to add to "intercept" these shutdown 
> messages?  Am I going about this the wrong way?  Thanks for any help.

By researching and a bit of trial and error, I discovered that it is 
necessary to use login() to append the utmp file so that the process 
receives these system messages.  Thanks.

José Alburquerque

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