Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: Fork and then exec problem with signals
Top Forums Programming Fork and then exec problem with signals Post 302460591 by achenle on Thursday 7th of October 2010 05:52:37 AM
Old 10-07-2010
Are execl(), printf(), and sleep() all async-signal safe?

I don't think execl() is, and I'd bet a lot that printf() isn't, and whether or not sleep() is async-signal safe probably depends on the implementation.

And FWIW, the custom signal-handler will not propagate across any of the exec()-type calls:

Quote:
execve() does not return on success, and the text, data, bss, and stack of the calling process are overwritten by that of the program loaded. The program invoked inherits the calling process's PID, and any open file descriptors that are not set to close-on-exec. Signals pending on the calling process are cleared. Any signals set to be caught by the calling process are reset to their default behaviour. The SIGCHLD signal (when set to SIG_IGN) may or may not be reset to SIG_DFL.
 

10 More Discussions You Might Find Interesting

1. Programming

Fork and exec

Hello! I am working on a server where I should have 4 (resident)processes, one of them being "the father" of the others, so I do 3 forks. The problem that I have is that I do an accept (for sockets) in the "father" process and I want to transmit the job to one of the processes "child" with... (3 Replies)
Discussion started by: driki
3 Replies

2. Programming

Problem with signals - 3 process communication

Hello, I would like to ask you for a little help with program I'm working on. I have problems with signals and synchronizing processes (I'm quite new to this part of programming). Process "parent" creates new child process "child1" and this process creates new child process "child2". The... (2 Replies)
Discussion started by: Nightwright
2 Replies

3. UNIX for Dummies Questions & Answers

FORK/EXEC technique

Hi! Can someone explain me exactly this technique? Why a process (PARENT) creates a copy of itself with FORK (CHILD)? What's the reason of this behaviour? Sorry, but I cannot understand the logic behind it. Thanks. (4 Replies)
Discussion started by: marshmallow
4 Replies

4. Programming

fork/exec clobbers write. I need ideas why...

On my *nix box, I have a telegram program. When I go like tel person "la\nla\nla\n" the person sees "la\nla\nla\n" However, when I have a program that forks and execs tel like: pid = fork(); if (pid < 0) { perror("fork failed"); exit(EXIT_FAILURE); } if (pid == 0) {... (7 Replies)
Discussion started by: frequency8
7 Replies

5. Solaris

fork and exec ftp

Hi, I need to find/implement an application that FTPs (puts) all new files in a certain directory to an external storage unit. This application should check for new files every 10 seconds (leaving the FTP connection open in between the 10 seconds). The easiest way would be if there are... (2 Replies)
Discussion started by: KittyJ
2 Replies

6. Shell Programming and Scripting

fork and exec

I need to ssh to a remote server and run my script there. This is my script. $ssh = "ssh username@host"; $cmd = "$ssh 'cd <my dir> && < sudo Run_exe>'"; my $pid = fork; if ($pid == 0){ exec $cmd; } When I run this I get: pccons_getchar: got r == 0 (1 Reply)
Discussion started by: looza
1 Replies

7. Programming

How forbid use fork() in exec() program.

Hello World! I am writing code in C++ which have to launch another application X using exec(). I would like to set some limits on it using setrlimit etc... My problem is that i don't know how to forbid using fork() and strlimit by application X. How can i do it? (3 Replies)
Discussion started by: kzi
3 Replies

8. Programming

Newbie question on exec,fork, wait,pipe C

Hello everybody.I want to make clear that i am not going to ask from anybody to build my asignement but i have a big problem. I can't seem to find anywhere ONE good example on C about what i am trying to do:wall:.I think it is simple. All i ask is one example, even a link is fine. So, i want to... (1 Reply)
Discussion started by: Cuervo
1 Replies

9. UNIX for Dummies Questions & Answers

fork with exec

What is is difference between 'fork with exec' and 'fork without exec'? How both are related? (1 Reply)
Discussion started by: kkalyan
1 Replies

10. UNIX for Beginners Questions & Answers

Question about global environment variables & fork() exec()

Hello... And thanks in advance for any help anyone can offer me on my question! I've been doing a lot of reading to try and find my answer... But I haven't had any luck What I'm trying to understand is where a child process inherits global environment variables from? I understand the exec()... (2 Replies)
Discussion started by: bodisha
2 Replies

LEARN ABOUT OPENSOLARIS

alarm

alarm(2)							   System Calls 							  alarm(2)

NAME

       alarm - schedule an alarm signal

SYNOPSIS

       #include <unistd.h>

       unsigned int alarm(unsigned int seconds);

DESCRIPTION

       The alarm() function causes the system to generate a SIGALRM signal for the process after the number of real-time seconds specified by sec-
       onds  have  elapsed (see  signal.h(3HEAD)). Processor scheduling delays may prevent the process from handling the signal as soon as  it	is
       generated.

       If  seconds  is	0,  a  pending	alarm  request,  if  any, is cancelled. If seconds is greater than LONG_MAX/hz, seconds is rounded down to
       LONG_MAX/hz. The value of hz is normally 100.

       Alarm requests are not stacked; only one SIGALRM  generation can  be  scheduled in this manner; if the SIGALRM signal has not yet been gen-
       erated, the call will result in rescheduling the time at which the SIGALRM signal will be generated.

       The  fork(2)  function clears pending alarms in the child process. A new process image created by one of the exec(2) functions inherits the
       time left to an alarm signal in the old process's image.

RETURN VALUES

       If there is a previous alarm request with time  remaining, alarm() returns  a  non-zero	value  that  is the number of  seconds	until  the
       previous request would  have  generated	a SIGALRM signal.  Otherwise, alarm() returns 0.

ERRORS

       The alarm() function is always successful; no return value is reserved to indicate an error.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       exec(2), fork(2), signal.h(3HEAD), attributes(5), standards(5)

SunOS 5.11							    6 Jun 2007								  alarm(2)
All times are GMT -4. The time now is 04:48 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy