start by setting up the signal handler before you create the child
And... consider not using functions like printf in a signal handler. See async-signal safe
functions:
Hi everybody,
I'm trying to understand how a parent and child processes interact.
This function( below) basically measures the fork time from the perspective of the parent only.
what i would like to know is how to measure the time from the perspective of parent and child (ie: inserting... (0 Replies)
I want to catch SIGCHLD signal in parent process. I can't use wait() system call to catch SIGCHLD according to project requirment.
Operating system linux 3.1
can any one have a solution for this.
Thanking you,
ranjan (2 Replies)
i am creating children processes using fork system call
every child i create goes to sleep for random time.
when child stops running how can i catch his signal and turminate the child (2 Replies)
Hi All,
I have two ksh script. 1st script calls the 2nd script and the second script calls an 'C' program.
I want 1st script to wait until the 'C' program completes.
I cant able to get the process id for the 'C' program (child process) to make the 1st script to wait for the second... (7 Replies)
Hey all, I need to launch a script from within 2 other scripts that can run independently of the two parent scripts... Im having a hard time doing this, if anyone knows how please let me know.
More detail.
ScriptA (bash), ScriptB (ksh), ScriptC (bash)
ScriptA, launches ScriptB
ScirptB,... (7 Replies)
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)
Discussion started by: vizz_k
2 Replies
LEARN ABOUT FREEBSD
kill
KILL(2) BSD System Calls Manual KILL(2)NAME
kill -- send signal to a process
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/types.h>
#include <signal.h>
int
kill(pid_t pid, int sig);
DESCRIPTION
The kill() system call sends the signal given by sig to pid, a process or a group of processes. The sig argument may be one of the signals
specified in sigaction(2) or it may be 0, in which case error checking is performed but no signal is actually sent. This can be used to
check the validity of pid.
For a process to have permission to send a signal to a process designated by pid, the user must be the super-user, or the real or saved user
ID of the receiving process must match the real or effective user ID of the sending process. A single exception is the signal SIGCONT, which
may always be sent to any process with the same session ID as the sender. In addition, if the security.bsd.conservative_signals sysctl is
set to 1, the user is not a super-user, and the receiver is set-uid, then only job control and terminal control signals may be sent (in par-
ticular, only SIGKILL, SIGINT, SIGTERM, SIGALRM, SIGSTOP, SIGTTIN, SIGTTOU, SIGTSTP, SIGHUP, SIGUSR1, SIGUSR2).
If pid is greater than zero:
The sig signal is sent to the process whose ID is equal to pid.
If pid is zero:
The sig signal is sent to all processes whose group ID is equal to the process group ID of the sender, and for which the process has
permission; this is a variant of killpg(2).
If pid is -1:
If the user has super-user privileges, the signal is sent to all processes excluding system processes (with P_SYSTEM flag set),
process with ID 1 (usually init(8)), and the process sending the signal. If the user is not the super user, the signal is sent to
all processes with the same uid as the user excluding the process sending the signal. No error is returned if any process could be
signaled.
For compatibility with System V, if the process number is negative but not -1, the signal is sent to all processes whose process group ID is
equal to the absolute value of the process number. This is a variant of killpg(2).
RETURN VALUES
The kill() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate
the error.
ERRORS
The kill() system call will fail and no signal will be sent if:
[EINVAL] The sig argument is not a valid signal number.
[ESRCH] No process or process group can be found corresponding to that specified by pid.
[EPERM] The sending process does not have permission to send sig to the receiving process.
SEE ALSO getpgrp(2), getpid(2), killpg(2), sigaction(2), sigqueue(2), raise(3), init(8)STANDARDS
The kill() system call is expected to conform to ISO/IEC 9945-1:1990 (``POSIX.1'').
HISTORY
The kill() function appeared in Version 7 AT&T UNIX.
BSD March 15, 2012 BSD