The message indicates that a call to
select()
has been interrupted. But your code snippets did not contain a call to
select()
.
There are a lot of questions and notes (besides my above comment about the incomplete handler function):
Why did you use
sigfillset()
when only handling specific signals?
It would be better to use
sigempty()
and add the signals that are handled.
What is
SIGU
?
It is not a standard signal.
A signal handler should call async-signal-safe functions only. See
man 7 signal[
^].
printf()
does not belong to these functions. When
display_menu()
does what it sounds like, it should definitely not called by a signal handler.