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You can't have this sort of information without knowing what kind of program you start I think. The latest link has an example of a program that's run via a terminal but dissociates itself from the controlling terminal. It's a normal practice for many daemons like smbd to drop its privileges to a special user
I wonder why you are even concerned about controlling terminals. Having one or not just affects the way you interact with a program, you are in charge over it anyways
Last edited by redfox2807; 12-12-2012 at 03:47 AM.
Could you be more specific? A program is always started by a user (i.e. with some user privileges) with the exception of init, that is triggered by Linux kernel directly. init defines and operates the whole user space. All the processes it triggers are run as root. Then in case of CLI login command is run. That's where a physical user comes into interaction with the system. As far as I can cogitate your intentions, your question goes to the area of user privileges, to define what a user is allowed to run and what's not. Maybe I'm just completely missing your point.
The concept of 'controlling terminal' is distinct from parental ancestry. All processes are children of some other process. The ps command shows the Parent Process ID (PPID). Is that the information you really want?
Any process can dissociate itself from a controlling terminal. Processes that do so are called daemons. Typically, these are launched as part of the system startup. Normally, a process is killed if it's controlling terminal closes (say, if the SSH connection is broken, or the modem hangs up, or an xterm gets closed). Daemon processes need to stay running perpetually, so cannot rely on a controlling terminal in order to stay alive.