What this code should do is: there are parent.cpp and child.cpp. Parent will send whatever is in the buffer to child and child will send back whatever received to parent. I do not know what I am doing wrong. I am confused what is missing in the parent and what else I should include into the child. Thanks.
I have been busy reading away on devices and filesystems and I am stuck on a particular subject matter.. I'm not understanding the concept behind mknod mkfifo makedev or related commands..
can anyone shed some light on the subject.!
any feedback welcome!
moxxx68 (0 Replies)
I'm having difficulty understanding the purposes of using dup/dup2 when involving forks.
for example, if we call fork() once, that is, we are creating a child process. In what cases would we need to use dup or dup2 to duplicate the file descriptors for standard output and standard error? What... (1 Reply)
I want to search for the line with the group name and add the user into the group. The file format is the same as /etc/group
The code i wrote is
egrep "^$newGID" $group >/dev/null
FS=":"
oldData=awk -F: '{print $3}'
newData= "$oldData,$newUser"
sed -n $4/$newData $group
but a friend... (1 Reply)
Hi,
i have in one program such a pice of code
................
static int old_stderr_handle = -1;
static int old_stdout_handle = -1;
log_handle = open(log_file_name,O_CREAT|O_RDWR,932);
old_stderr_handle = dup(STDERR_FILENO);
if (dup2(log_handle,STDERR_FILENO) < 0)
{
//... (1 Reply)
int redirect()
{
int fd,rc;
fd = open("sample.DAT",O_CREAT | O_RDWR , 00777 );
rc = dup2(fd , 1 ) ;
close (fd );
return 0;
}
I used the above to redirect all the cout statements to sample.DAT. process is redirecting the output and I had two questions
1. All stdout/cout statements... (2 Replies)
Hi all,I'm reading <Advanced programming in the UNIX environment>,that book asked the reader to implement a function which has same functions with dup2 without calling fcntl.Could anyone give me a tip?Any help will be appreciated.:) (8 Replies)
is it possible to duplicate file descriptors(opened by a different process) with the help of dup or dup2. the two process do not share parent child relationship as well. (2 Replies)
Hi guys,
I need to know how i can ignore Pipe '|' if Pipe is coming as a column in Pipe delimited file
for eg:
file 1:
xx|yy|"xyz|zzz"|zzz|12...
using below awk command
awk 'BEGIN {FS=OFS="|" } print $3
i would get xyz
But i want as :
xyz|zzz to consider as whole column... (13 Replies)
I want to execute metasploit by two pipes to communicate with it, but I have troubles with that communication. When I run my program, I get this error: "stty: standard input: Inappropriate ioctl for device" and I don't receive the metasploit promt.
just select an exploit.
This is my code:... (2 Replies)
Discussion started by: dano88
2 Replies
LEARN ABOUT XFREE86
pthread_atfork
PTHREAD_ATFORK(3) Library Functions Manual PTHREAD_ATFORK(3)NAME
pthread_atfork - register handlers to be called at fork(2) time
SYNOPSIS
#include <pthread.h>
int pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void));
DESCRIPTION
pthread_atfork registers handler functions to be called just before and just after a new process is created with fork(2). The prepare han-
dler will be called from the parent process, just before the new process is created. The parent handler will be called from the parent
process, just before fork(2) returns. The child handler will be called from the child process, just before fork(2) returns.
One or several of the three handlers prepare, parent and child can be given as NULL, meaning that no handler needs to be called at the cor-
responding point.
pthread_atfork can be called several times to install several sets of handlers. At fork(2) time, the prepare handlers are called in LIFO
order (last added with pthread_atfork, first called before fork), while the parent and child handlers are called in FIFO order (first
added, first called).
To understand the purpose of pthread_atfork, recall that fork(2) duplicates the whole memory space, including mutexes in their current
locking state, but only the calling thread: other threads are not running in the child process. The mutexes are not usable after the fork
and must be initialized with pthread_mutex_init in the child process. This is a limitation of the current implementation and might or
might not be present in future versions.
RETURN VALUE
pthread_atfork returns 0 on success and a non-zero error code on error.
ERRORS
ENOMEM insufficient memory available to register the handlers.
AUTHOR
Xavier Leroy <Xavier.Leroy@inria.fr>
SEE ALSO fork(2), pthread_mutex_lock(3), pthread_mutex_unlock(3).
LinuxThreads PTHREAD_ATFORK(3)