FORK(2) | System Calls Manual | FORK(2) |
fork
— create a
new process
#include
<unistd.h>
pid_t
fork
(void);
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:
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).
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.
fork
() will fail and no child process will
be created if:
EAGAIN
]EAGAIN
]RLIMIT_NPROC
on the total number of
processes under execution by the user ID would be exceeded.ENOMEM
]The fork
() function conforms to
IEEE Std 1003.1-2008 (“POSIX.1”).
The fork
() system call first appeared in
Version 1 AT&T UNIX.
September 10, 2015 | OpenBSD-6.6 |