03-20-2001
Advantages of using a fork? You dont get spaghetti sauce on your hands....
Please read the <A HREF="http://www.rahul.net/cgi-bin/userbin/man?topic=fork§ion=2">fork(2)</A> man page. It should answer most of your questions.
10 More Discussions You Might Find Interesting
1. Programming
I run this code, actually I want to both processes print the message from "data". But only one does. What happens? Anyone can help?
#include <stdio.h>
main(){
int fd, pid;
char x;
fd = open("data",0); /* open file "data" */
pid = fork();
if(pid != 0){
wait(0);
... (2 Replies)
Discussion started by: Herman
2 Replies
2. Programming
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#define MAX_COUNT 200
#define BUF_SIZE 100
void main(void)
{
pid_t pid;
int i;
char buf;
fork();
pid = getpid();
for (i = 1; i <= MAX_COUNT; i++) {
sprintf(buf,... (2 Replies)
Discussion started by: MKSRaja
2 Replies
3. Programming
Hello all.
I'm developing a filetransfer application, which is supposed to work sort of like dcc, with multiple transfers etc. Now i wonder what the best way to manage the transfers is. Should i fork() for each new transfer, hogging loads of memory or use pthreads? Maybe I can use select to see... (0 Replies)
Discussion started by: crippe
0 Replies
4. Programming
hi all
About this code
for (i = 1; i < n; i++)
if ((childpid = fork()) <= 0)
break;
I really can't understand the output .
and the way fork () return the value .
how about the process Id ,the child process Id and the parent ID
in this case
so please answer me soon (5 Replies)
Discussion started by: iwbasts
5 Replies
5. Programming
Hi everybody,
I wanna write a code to understand how fork works.
my target
--------------
-Parent creates a file(called temp) and writes into this file "1".Then it closes the file.
-Then parent creates a child and wait until execution of this child ends.
-Then child opens the same... (3 Replies)
Discussion started by: alexicopax
3 Replies
6. UNIX for Advanced & Expert Users
Hi,
I wrote a simple program for understanding the fork command. The code is as below
int main(void)
{
fork(); printf("hi 1 \n");
fork(); printf("hi 2 \n");
fork(); printf("hi 3 \n");
}
I am getting a variation in the number of times the printf is called if i remove the \n from each of... (1 Reply)
Discussion started by: xyz123456
1 Replies
7. Programming
Hi,
I wrote a simple program for understanding the fork command. The code is as below
int main(void)
{
fork(); printf("hi 1 \n");
fork(); printf("hi 2 \n");
fork(); printf("hi 3 \n");
}
I am getting a variation in the number of times the printf is called if i remove the \n from each... (2 Replies)
Discussion started by: xyz123456
2 Replies
8. Programming
does fork() spawn only the parent process, what if fork() is looped, does it spawn the parent and the child? (4 Replies)
Discussion started by: Peevish
4 Replies
9. UNIX for Dummies Questions & Answers
I'm trying to run a simple test on how to use fork(), i'm able to execute the child process first then the parent, but how can I execute parent then child..?
Thanks! (1 Reply)
Discussion started by: l flipboi l
1 Replies
10. Programming
I understand that fork create a child but I need very simple example that make child useful....
I mean how will make the program faster anyone explain with code plz
using C plz (2 Replies)
Discussion started by: fwrlfo
2 Replies
FORK(2) BSD System Calls Manual FORK(2)
NAME
fork -- create a new process
LIBRARY
Standard C Library (libc, -lc)
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(2) or write(2) 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 process' resource utilizations are set to 0; see setrlimit(2).
In general, the child process should call _exit(2) rather than exit(3). Otherwise, any stdio buffers that exist both in the parent and child
will be flushed twice. Similarly, _exit(2) should be used to prevent atexit(3) routines from being called twice (once in the parent and once
in the child).
In case of a threaded program, only the thread calling fork() is still running in the child processes.
Child processes of a threaded program have additional restrictions, a child must only call functions that are async-signal-safe. Very few
functions are asynchronously safe and applications should make sure they call exec(3) as soon as possible.
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-depen-
dent.
[EAGAIN] The limit RLIMIT_NPROC on the total number of processes under execution by this user id would be exceeded.
[ENOMEM] There is insufficient swap space for the new process.
SEE ALSO
execve(2), setrlimit(2), vfork(2), wait(2), pthread_atfork(3)
STANDARDS
The fork() function conforms to ISO/IEC 9945-1:1990 (``POSIX.1'').
HISTORY
A fork() system call appeared in Version 6 AT&T UNIX.
BSD
June 10, 2004 BSD