10 More Discussions You Might Find Interesting
1. Shell Programming and Scripting
I am having issues with trap not working inside a script. I am currently trying this on a Knoppix system V 5.1. What I would like to happen is when I press control c, a message gets echoed and the script is ended. For example:
#! /bin/bash
trap "echo CTRL c was pressed ; break" SIGINT... (11 Replies)
Discussion started by: Basherrr
11 Replies
2. UNIX for Advanced & Expert Users
Hi All,
The problem statement is as below:
Problem: A process (exe) is getting executed in background. The output of this process is getting logged in a file. After successfully running for some time the process gets terminated. In the log file following is present:
^M[7m Interrupt ^M[27m... (8 Replies)
Discussion started by: Praty.27
8 Replies
3. UNIX for Dummies Questions & Answers
I was wondering about following. If I have set of 3 signals. And they are all blocked.Now at some point in the program the set is unblocked. Which signal will be delivered first.This is my set....SIGTSTP,SIGQUIT,SIGINT.When I added them in the set and unblock them I did it in following order...
... (1 Reply)
Discussion started by: joker40
1 Replies
4. UNIX for Dummies Questions & Answers
I know how to add signal to a set. But what if I want to add 2 or 3 signals to the set.
I know I can use sigaddset (&set,SIGBUS)....but what if I want to add SIGBUS and SIGALRM at once. Do i have to do it like this..
sigaddset (&set,SIGBUS);
sigaddset (&set,SIGALRM);
Is there another way to... (0 Replies)
Discussion started by: joker40
0 Replies
5. UNIX for Dummies Questions & Answers
I have following problem with this code..
First time trough the main loop.....
perror gives ....blocked signal:success(all other times gives illlegal seek)
Should every time trought the main loop be success??
And the perror otside of main loop...didn't change mask:success
That line of code... (2 Replies)
Discussion started by: joker40
2 Replies
6. UNIX for Dummies Questions & Answers
I am having trouble with folowing
sigset_t s; // now s represents set of signals
sigemptyset(&s) ; // initialize this set and exclude all the signals from it.is it empty?
sigaddset(&s,SIGILL);//this set containts only SIGILL signal
sigprocmask(SIG_BLOCK,&s,NULL);//lost on this one
Can... (3 Replies)
Discussion started by: joker40
3 Replies
7. Programming
Hi,
In our program, we are using SIGTERM and i tired to put break point in this function. But my debuger is unable to brake at that point.
I am working on Mac X and using XCode.
Thanks (1 Reply)
Discussion started by: Saurabh78
1 Replies
8. Programming
How can use signals in a C program If i want a child program to signal it's parent program that it(child) program has completed the task that it was assigned.:confused: (2 Replies)
Discussion started by: kapilv
2 Replies
9. UNIX for Dummies Questions & Answers
(posted this in the scripting forum as well, but figured it should go here) So, what's going on is this:
For our program, we had to create our own shell, and if the user pressed ctrl-c just at the cmdline, then this signal would be ignored, but if there is a foreground process running, let's... (0 Replies)
Discussion started by: blind melon
0 Replies
10. Programming
does the way of handling, interrupting signals in HP-UX same as that of solaris. If there is difference than what it is.?:confused: (1 Reply)
Discussion started by: kapilv
1 Replies
SIGNAL(2) System Calls Manual SIGNAL(2)
NAME
signal - catch or ignore signals
SYNOPSIS
#include <signal.h>
(*signal(sig, func))()
(*func)();
DESCRIPTION
A signal is generated by some abnormal event, initiated either by user at a typewriter (quit, interrupt), by a program error (bus error,
etc.), or by request of another program (kill). Normally all signals cause termination of the receiving process, but a signal call allows
them either to be ignored or to cause an interrupt to a specified location. Here is the list of signals with names as in the include file.
SIGHUP 1 hangup
SIGINT 2 interrupt
SIGQUIT 3* quit
SIGILL 4* illegal instruction (not reset when caught)
SIGTRAP 5* trace trap (not reset when caught)
SIGIOT 6* IOT instruction
SIGEMT 7* EMT instruction
SIGFPE 8* floating point exception
SIGKILL 9 kill (cannot be caught or ignored)
SIGBUS 10* bus error
SIGSEGV 11* segmentation violation
SIGSYS 12* bad argument to system call
SIGPIPE 13 write on a pipe or link with no one to read it
SIGALRM 14 alarm clock
SIGTERM 15 software termination signal
16 unassigned
The starred signals in the list above cause a core image if not caught or ignored.
If func is SIG_DFL, the default action for signal sig is reinstated; this default is termination, sometimes with a core image. If func is
SIG_IGN the signal is ignored. Otherwise when the signal occurs func will be called with the signal number as argument. A return from the
function will continue the process at the point it was interrupted. Except as indicated, a signal is reset to SIG_DFL after being caught.
Thus if it is desired to catch every such signal, the catching routine must issue another signal call.
When a caught signal occurs during certain system calls, the call terminates prematurely. In particular this can occur during a read or
write(2) on a slow device (like a typewriter; but not a file); and during pause or wait(2). When such a signal occurs, the saved user sta-
tus is arranged in such a way that when return from the signal-catching takes place, it will appear that the system call returned an error
status. The user's program may then, if it wishes, re-execute the call.
The value of signal is the previous (or initial) value of func for the particular signal.
After a fork(2) the child inherits all signals. Exec(2) resets all caught signals to default action.
SEE ALSO
kill(1), kill(2), ptrace(2), setjmp(3)
DIAGNOSTICS
The value (int)-1 is returned if the given signal is out of range.
BUGS
If a repeated signal arrives before the last one can be reset, there is no chance to catch it.
The type specification of the routine and its func argument are problematical.
ASSEMBLER
(signal = 48.)
sys signal; sig; label
(old label in r0)
If label is 0, default action is reinstated. If label is odd, the signal is ignored. Any other even label specifies an address in the
process where an interrupt is simulated. An RTI or RTT instruction will return from the interrupt.
SIGNAL(2)
