Signals

[shirono at hcx3.SSD.HARRIS.COM]

In comp.unix.questions, pete at titan.titan.rice.edu writes:
> I'm trying to write a simple implementation of an Unix shell to be used as a 
> lab in a class, but I'm having problems handling ^Z. 
>
> I install a handler for SIGTSTP via 'signal' and then send SIGSTOP to the
> proper child via 'kill'. 'ps' says at this point the child is stopped and
> soon swaps out. The parent is marked as sleeping. A 'printf' call followed
> by a fflusch call immediately follows the 'kill', but it never happens.
            ^

First, remember it is not necessarily ^Z.  It is whatever you told the
terminal driver to interpret as the suspend character.

You say you send SIGSTOP.  That is most definitely going to stop your process.
You have no say in the matter.

SIGSTOP and SIGTSTP are two different signals.  The first one cannot be
caught, blocked or ignored.  The second one is the stop signal generated from
the keyboard.  Do not mix them.

Good luck.

--Roberto
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