Member Avatar for wschamps42

Can somone please explain to me what does fork() != 0 mean? From what I understand I think it means if fork is not false? Or if fork is true then.... I dont understand how Fork() can be true or false, seeing that it just creates a copy of a process into a parent and child.

1 #include "csapp.h"
2
3 int main()
4  {
5    int x = 3;
6
7    if (Fork() != 0)
8        printf("x=%d\n", ++x);
9
10   printf("x=%d\n", --x);
11   exit(0);
12  }

EDIT: Also if a program where to say "if (Fork() == 0)" what would that mean?

Edited by wschamps42
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  • Latest Post Latest Post by np complete
Member Avatar for gerard4143

The return value of fork() will explain your questions

RETURN VALUE
On success, the PID of the child process is returned in the parent, and 0
is returned in the child. On failure, -1 is returned in the parent, no
child process is created, and errno is set appropriately.

Member Avatar for nitin1

can anyone give me nice tutorial of this fork() ? I just know only one thing which gerard said. i want to ask where is child process which is created ? This process is parent one. and how can we deal with child one ? hoping for best answers . ;)

Member Avatar for np complete

@ nitin1

Don't you google your query first ?

Anyways, I found a tutorial, which starts with the basics. See this.

Also wiki has a nice article on fork() and forking in *nix systems.

There aremany tutorials that I found googling. You can also go through them.

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