ctrl-c doesn't work but ctrl-z is ok in telnet

[David Daney]

Bin Chen wrote:
> A little update for this problem, I wrote a propram to test the CTRL-C
> signal, I found if I call:
> 
> signal(SIGINT, handler);
> 
> in main(), then the program can get the SIGINT when I press CTRL-C, but
> if I comment out this line, the SIGINT can't cause the program exit.
> 
> I think this is caused by the default SIGINT processing logic inherited
> from the busybox shell, right? In older busybox version we didn't
> encounter this before, so maybe the reason is the default processing
> logic for SIGINT in older busybox shell is exit.
> 
> Will a program started from shell inherit the signal processing
> properties from the shell?
> 

That explains it.  I have a busybox 1.00 system that has been annoying 
me with this behavior.

The setting of SIG_DFL/SIG_IGN and the signal mask are inherited by 
child processes.  If telnetd masked SIGINT or set it to SIG_IGN that 
might keep the child processes from receiving the SIGINT.


David Daney.