10-08-2001
Thanks a lot rwb1959!!
Your suggestion looks great. I shall better try this rather than using fork. I have already implemented the fork mechanism but I started to be a bit worried after looking at your responses.
Anyway thanks a lot for the help.
10 More Discussions You Might Find Interesting
1. Programming
Hy!
I must wrote some code with fork() command. The thing is that i have a while statement which count till 10.
I must wrote a program that one child has only one parent. So one parent has only one child and one child has only one parent. Can you please help me with these code.
int main()... (2 Replies)
Discussion started by: davidoff
2 Replies
2. Programming
One more question. How can i calculate the time that system needs to make fork() system call? I need to make it with times function but i really don't know how. :( (2 Replies)
Discussion started by: davidoff
2 Replies
3. UNIX for Dummies Questions & Answers
Can anyone explain me what really happens when a system call fork() is called ?
I like to know what happens internally.
Thanks in Advance.
- Arun (1 Reply)
Discussion started by: arunviswanath
1 Replies
4. Programming
Hi,
I try to write a C program which lists the output of a paticular command with all the available options (a to z) for the command in the directory of execution.
This program will generate the output if the option exists for the particular command else it will display some message saying... (9 Replies)
Discussion started by: ramkrix
9 Replies
5. UNIX for Dummies Questions & Answers
Hi folks,
I want to know how this below program works?
#include <stdio.h>
int main()
{
printf("A\n");
fork();
printf("B\n");
fork();
fork();
printf("D\n");
fork();
printf("C\n");
}
This is just for example. How this type of programs where fork is used many places, how the... (1 Reply)
Discussion started by: u_peerless
1 Replies
6. Homework & Coursework Questions
Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted!
1. The problem statement, all variables and given/known data:
i have a problem in understanding the behaviour of fork .
i understood fork as to create a new process and... (4 Replies)
Discussion started by: MrUser
4 Replies
7. Shell Programming and Scripting
hi,
i tried the following source codes:
fork1.c:
main()
{
printf("demo of fork\n");
fork();
printf("hello");
}
output:
demo of fork
hello hello
fork2.c:
main()
{
printf("demo of fork"); (0 Replies)
Discussion started by: pnirmala
0 Replies
8. Programming
hi all,
i tried the following source codes:
fork1.c:
main()
{
printf("demo of fork\n");
fork();
printf("hello");
}
output:
demo of fork
hello hello
fork2.c:
main() (3 Replies)
Discussion started by: pnirmala
3 Replies
9. UNIX for Advanced & Expert Users
Hi
I wrote a simple fork program to illustrate the fork() system cal. here it is
#include<stdio.h>
#include<sys/stat.h>
#include<sys/types.h>
main()
{
int flag;
flag=fork();
if(flag==0)
{
printf("Child \n");
printf("Process id= %d\n",getpid());
... (3 Replies)
Discussion started by: badsha6642
3 Replies
10. Shell Programming and Scripting
Hi, I'm writing a shell script where I want to call fork(). However I wrote like this "var=fork()" in c style and got this error:
"syntax error near unexpected token `(' "
How could I call fork() in shell script? Thanks in advance.
Duplicate Post - Continue Here - Please Do Not Cross Post... (0 Replies)
Discussion started by: Xiaoya
0 Replies
VFORK(2) BSD System Calls Manual VFORK(2)
NAME
vfork -- spawn new process in a virtual memory efficient way
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <unistd.h>
pid_t
vfork(void);
DESCRIPTION
The vfork system call creates a new process that does not have a new virtual address space, but rather shares address space with the parent,
thus avoiding potentially expensive copy-on-write operations normally associated with creating a new process. It is useful when the purpose
of fork(2) would have been to create a new system context for an execve(2). The vfork system call differs from fork(2) in that the child
borrows the parent's memory and thread of control until a call to execve(2) or an exit (either by a call to _exit(2) or abnormally). The
parent process is suspended while the child is using its resources.
The vfork system call returns 0 in the child's context and (later) the pid of the child in the parent's context.
The vfork system call can normally be used just like fork(2). It does not work, however, to return while running in the childs context from
the procedure that called vfork() since the eventual return from vfork() would then return to a no longer existent stack frame. Be careful,
also, to call _exit(2) rather than exit(3) if you can't execve(2), since exit(3) will flush and close standard I/O channels, and thereby mess
up the standard I/O data structures in the parent process. (Even with fork(2) it is wrong to call exit(3) since buffered data would then be
flushed twice.)
RETURN VALUES
Same as for fork(2).
ERRORS
Same as for fork(2).
SEE ALSO
execve(2), fork(2), sigaction(2), wait(2)
HISTORY
The vfork() function call appeared in 3.0BSD. In 4.4BSD, the semantics were changed to only suspend the parent. The original semantics were
reintroduced in NetBSD 1.4.
BUGS
Users should not depend on the memory sharing semantics of vfork() as other ways of speeding up the fork process may be developed in the
future.
To avoid a possible deadlock situation, processes that are children in the middle of a vfork() are never sent SIGTTOU or SIGTTIN signals;
rather, output or ioctl(2) calls are allowed and input attempts result in an end-of-file indication.
BSD
January 3, 1998 BSD