Linux Programmer's Manual
NAME
fork - create a child process
SYNOPSIS
#include <unistd.h>
pid_t fork(void);
DESCRIPTION
fork() creates a new process by duplicating the calling process. The
new process, referred to as the child, is an exact duplicate of the
calling process, referred to as the parent, except for the following
points:
* The child has its own unique process ID, and this PID does not match
the ID of any existing process group (setpgid(2)).
* The child's parent process ID is the same as the parent's process
ID.
* The child does not inherit its parent's memory locks (mlock(2),
mlockall(2)).
* Process resource utilizations (getrusage(2)) and CPU time counters
(times(2)) are reset to zero in the child.
* The child's set of pending signals is initially empty (sigpend‐
ing(2)).
* The child does not inherit semaphore adjustments from its parent
(semop(2)).
* The child does not inherit record locks from its parent (fcntl(2)).
* The child does not inherit timers from its parent (setitimer(2),
alarm(2), timer_create(2)).
* The child does not inherit outstanding asynchronous I/O operations
from its parent (aio_read(3), aio_write(3)), nor does it inherit any
asynchronous I/O contexts from its parent (see io_setup(2)).