These signals are used for various other purposes. In general, they will not affect your program unless it explicitly uses them for something.
SIGUSR1
and SIGUSR2
signals are set aside for you to
use any way you want. They're useful for simple interprocess
communication, if you write a signal handler for them in the program
that receives the signal.
There is an example showing the use of SIGUSR1
and SIGUSR2
in section Signaling Another Process.
The default action is to terminate the process.
If a program does full-screen display, it should handle SIGWINCH
.
When the signal arrives, it should fetch the new screen size and
reformat its display accordingly.
If the process is the leader of the process group, the default action is to print some status information about the system and what the process is doing. Otherwise the default is to do nothing.
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