Sponsored Content
Full Discussion: signal handler problems
Top Forums Programming signal handler problems Post 85877 by Perderabo on Friday 7th of October 2005 04:19:25 PM
Old 10-07-2005
You should not use signal() for new code. But if you do, you must repeat the call to signal as the first line in the signal handler. The signal goes back to the default action each time with signal(). This is dumb and that is why no one uses signal() anymore.

Ideally, use sigaction() instead. Then whether or not the signal get reset each time is controlled with a flag and you do not want to set that flag.
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

shell script signal handler

AIX 4.3.3 I am trying to write a signal handler into a ksh shell script. I would like to capture the SIGTERM, SIGINT, and the SIGTSTP signals, print out a message to the terminal, and continue executing the script. I have found a way to block the signals: #! /bin/ksh SIGTERM=15 SIGINT=2... (2 Replies)
Discussion started by: jalburger
2 Replies

2. Programming

signal handler for SIGCHLD

Hi, I have an c++ application which uses the function fork and execvp(). The parent does not wait until the child ends. The parents just creates children and let them do their stuff. You can see the parent program as a batch-manager. I have added a SIGCHLD handler to the program: void... (3 Replies)
Discussion started by: jens
3 Replies

3. Programming

Runaway SIGALRM signal handler

I have written a program to demonstrate a problem I have encountered when using BSD style asynchronous input using the O_ASYNC flag in conjunction with a real time interval timer sending regular SIGALRM signals to the program. The SIGIO handler obeys all safe practices, using only an atomic update... (8 Replies)
Discussion started by: stewartw
8 Replies

4. Programming

Usage of exit() inside a signal handler

Is it ok to use exit() inside a signal handler? I catch SIGUSR1 in a signal handler and I try to close a file and then exit. The result is inconsistent. Sometimes the process exit and sometimes it returns to the original state before the signal handler was invoked. Perhaps exit is not legal in... (8 Replies)
Discussion started by: Tuvia
8 Replies

5. Programming

Problem with signal handler and interrupted system call

Hi, I have a daq program that runs in an infinite loop until it receives SIGINT. A handler catches the signal and sets a flag to stop the while loop. After the loop some things have to be cleaned up. The problem is that I want my main while loop to wait until the next full second begins, to... (2 Replies)
Discussion started by: soeckel
2 Replies

6. Shell Programming and Scripting

Perl - Problems with Signal Handler

I have a problem with signal handlers not working. I have a long 1000 line code and somehow this code for signal handling is not working: $SIG{INT} = \&interrupt; sub interrupt { print STDERR "Caught a control c!\n"; exit; # or just about anything else you'd want to do } Any... (2 Replies)
Discussion started by: som.nitk
2 Replies

7. Programming

Signal Handler Hangs

Hi, I have a problem with signal handler algorithm in linux. My code is hanging ( It is continuously looping inside the signal handler) . I am pasting my code here... Please provide me some help regarding this. I googled many places and wrote this code.. but doesnt seem to be working without... (6 Replies)
Discussion started by: sree_ec
6 Replies

8. Shell Programming and Scripting

Perl Signal Handler

I was working on some Perl code that does signal handling and I came across this one liner and wasn't sure what it was doing. local $SIG{__DIE__} = sub {$! = 2; die $_;}; I think the first part of the anonymous subroutine is setting $! to 2, but I am not sure what the second part is doing. ... (1 Reply)
Discussion started by: SFNYC
1 Replies

9. Programming

problem in doing coding of signal handler

i m unble to execute code of signal handler using a) Wait b) Waitpid (1 Reply)
Discussion started by: madhura
1 Replies

10. Programming

Serial port signal(IRQ) handler (using C)

Hello, I'm writing some serial(UART) handler but have stuck on few issues, maybe anyone can help to show me what I'm doing wrong. Basically I'm intending to write serial RX signal handler. Application receives defined packages of data over serial which contains header and payload. Handler... (3 Replies)
Discussion started by: Lauris_k
3 Replies
SIGINTERRUPT(3) 					   BSD Library Functions Manual 					   SIGINTERRUPT(3)

NAME
siginterrupt -- allow signals to interrupt system calls LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <signal.h> int siginterrupt(int sig, int flag); DESCRIPTION
The siginterrupt() function is used to change the system call restart behavior when a system call is interrupted by the specified signal. If the flag is false (0), then system calls will be restarted if they are interrupted by the specified signal and no data has been transferred yet. System call restart is the default behavior on 4.2BSD. If the flag is true (1), then restarting of system calls is disabled. If a system call is interrupted by the specified signal and no data has been transferred, the system call will return -1 with the global variable errno set to EINTR. Interrupted system calls that have started transferring data will return the amount of data actually transferred. System call interrupt is the signal behavior found on 4.1BSD and AT&T System V UNIX systems. Note that the new 4.2BSD signal handling semantics are not altered in any other way. Most notably, signal handlers always remain installed until explicitly changed by a subsequent sigaction(2) call, and the signal mask operates as documented in sigaction(2). Programs may switch between restartable and interruptible system call operation as often as desired in the execution of a program. Issuing a siginterrupt(3) call during the execution of a signal handler will cause the new action to take place on the next signal to be caught. NOTES
This library routine uses an extension of the sigaction(2) system call that is not available in 4.2BSD, hence it should not be used if back- ward compatibility is needed. RETURN VALUES
A 0 value indicates that the call succeeded. A -1 value indicates that an invalid signal number has been supplied. SEE ALSO
sigaction(2), sigprocmask(2), sigsuspend(2) HISTORY
The siginterrupt() function appeared in 4.3BSD. BSD
June 4, 1993 BSD
All times are GMT -4. The time now is 03:59 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy