Hi,
Recently I was reading some c coding by some colleagues and I noticed that the above trend. They will create a pipe for the process then they will use the standard signal handler to capture a particular signal and write that signal to the pipe. On the other end, the process will read the... (7 Replies)
Hi!
I want to catch all signals that my program receives print their name and then execute the default handler.
Can you help me on that?
I've tried the following code:
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
void (*hnd)(int i);
char signals =
{
"SIGHUP",... (7 Replies)
Hi All,
I facing a problem in handling signals between parent process communication. I am trying to send a signal(SIGINT) from child to parent. I am using kill function to do so and I am trying to read the signal using sigaction(). But the program is ending abruptly and I am not able to figure out... (4 Replies)
Hello all!
I'm writing a script that will catch when an outside process crashes (SIGHUP, right?) without having to loop into infinity.
With that in mind, I came across the trap utility and thought if could be used to monitor another process other than it's own. But from what I've read, I'm... (1 Reply)
I'm trying to do a program that makes activate an signal (SINGALARM) when the next child of a son appears but this not works.
I have to caught the next child o the other (pid), to send a singnal which inform a menssage.
It's anything worng in the code?
thanks.
the code:
#include... (2 Replies)
Hello. I want to make a child do some stuff,wait,then the parent does some stuff and then child does some stuff and waits again.I have made the following but it does not work.Can anybody help me?
pid1 = fork();
if (pid1 == -1)
{
perror("Can't create child\n");
... (18 Replies)
Hi, i want that the parent process start before the child, this code doesn't work,
if the child start before the parent it wait for signal, then the father send the signal SIGALRM and the child catch it and call printf;
else the father call printf and send the signal to the child that call its... (1 Reply)
Hello, everyone.
Here's a program:
pid_t pid = fork();
if (0 == pid) // child process
{
execvp ...;
}
I send a signal (such as SIGINT) to the parent process, the child process receive the signal as well as the parent process.
However I don't want to child process to receive the... (7 Replies)
Hi everyone
i am very new to linux , working on bash shell.
I am trying to solve the given problem
1. Create a process and then create children using fork
2. Check the Status of the application for successful running.
3. Kill all the process(threads) except parent and first child... (2 Replies)
Hi, I would like to ask, if is it possible to quit running loop in the script any other way than catching the trap signal. Ctrl-C ends only current running instance of process but not whole script. Any clues? (3 Replies)
Discussion started by: smoofy
3 Replies
LEARN ABOUT OSX
fork
FORK(2) BSD System Calls Manual FORK(2)NAME
fork -- create a new process
SYNOPSIS
#include <unistd.h>
pid_t
fork(void);
DESCRIPTION
Fork() causes creation of a new process. The new process (child process) is an exact copy of the calling process (parent process) except for
the following:
o The child process has a unique process ID.
o The child process has a different parent process ID (i.e., the process ID of the parent process).
o The child process has its own copy of the parent's descriptors. These descriptors reference the same underlying objects, so that,
for instance, file pointers in file objects are shared between the child and the parent, so that an lseek(2) on a descriptor in the
child process can affect a subsequent read or write by the parent. This descriptor copying is also used by the shell to establish
standard input and output for newly created processes as well as to set up pipes.
o The child processes resource utilizations are set to 0; see setrlimit(2).
RETURN VALUES
Upon successful completion, fork() returns a value of 0 to the child process and returns the process ID of the child process to the parent
process. Otherwise, a value of -1 is returned to the parent process, no child process is created, and the global variable errno is set to
indicate the error.
ERRORS
Fork() will fail and no child process will be created if:
[EAGAIN] The system-imposed limit on the total number of processes under execution would be exceeded. This limit is configuration-
dependent.
[EAGAIN] The system-imposed limit MAXUPRC (<sys/param.h>) on the total number of processes under execution by a single user would
be exceeded.
[ENOMEM] There is insufficient swap space for the new process.
LEGACY SYNOPSIS
#include <sys/types.h>
#include <unistd.h>
The include file <sys/types.h> is necessary.
SEE ALSO execve(2), sigaction(2), wait(2), compat(5)HISTORY
A fork() function call appeared in Version 6 AT&T UNIX.
CAVEATS
There are limits to what you can do in the child process. To be totally safe you should restrict yourself to only executing async-signal
safe operations until such time as one of the exec functions is called. All APIs, including global data symbols, in any framework or library
should be assumed to be unsafe after a fork() unless explicitly documented to be safe or async-signal safe. If you need to use these frame-
works in the child process, you must exec. In this situation it is reasonable to exec yourself.
4th Berkeley Distribution June 4, 1993 4th Berkeley Distribution