How does nohup work?

Question

Hello,

What is performed behind the scenes when a program runs with nohup?

Is the PID of the parent process being changed?

Thanks.

EDIT: I understood that nohup (and disown) causes that SIGHUP is not sent to the process if the parent process receives it. Does it mean that it is equivalent to handling SIGHUP (and actually ignore it)?

Answer 1

The Wikipedia article about nohup explains it pretty well.

Answer 2

Use the source, Luke!

Answer 3

It is equivalent to setting the SIGHUP handler to SIG_IGN, ie.

signal(SIGHUP, SIG_IGN);