weinelt@sbsvax.cs.uni-sb.de (Bernhard Weinelt) (02/23/90)
Hello folks, I have a new interesting (at least for me) question:
Suppose the following little program:
#include <stdio.h>
#include <signal.h>
main()
{
int c;
system("stty -echo cbreak");
/*signal(SIGSEGV,SIG_IGN);*/
while ((c=getchar())!=4) printf("%c",c);
system("stty echo -cbreak");
}
With the signal in comments, the program works as expected:
it echo's all characters and exits on ^D.
But with the signal statement in the program, after pressing
^D there is no more reaction at the terminal and in fact
the program has spawn a new sh-process, which is indefinitly
running. A very costly behaviour on our ULTRIX and BSD4.3
VAX's.
[With SunOS the above program works fine with the signal
statement.]
Exchanging SIG_IGN by an empty function also fixes the
problem. But can anybody explain this strange behaviour?
Thanks in advance.
Bernhard
--
------------------------------------
__________________ | Bernhard Weinelt |
(__) / \ | Universitaet des Saarlandes |
(oo) ( Many Greetings ) | FB 10 - Informatik (Dept. of CS) |
/-------\/ --'\__________________/ | Bau 36, Im Stadtwald 15 |
/ | || | D-6600 Saarbruecken 11, W-Germany|
* ||----|| | weinelt@cs.uni-sb.de |
~~ ~~ ------------------------------------