BSD 2.11 - man page for fork (bsd section 2)
|Linux & Unix Commands - Search Man Pages
fork - create a new process
pid = fork()
Fork causes creation of a new process. The new process (child process) is an exact copy
of the calling process except for the following:
The child process has a unique process ID.
The child process has a different parent process ID (i.e., the process ID of the par-
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 or write 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.
The child processes resource utilizations are set to 0; see setrlimit(2).
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 one or more of the following are
[EAGAIN] The system-imposed limit on the total number of processes under execution
would be exceeded. This limit is configuration-dependent.
[EAGAIN] The system-imposed limit MAXUPRC (<sys/param.h>) on the total number of
processes under execution by a single user would be exceeded.
[ENOMEM] There is insufficient swap space for the new process.
3rd Berkeley Distribution May 22, 1986 FORK(2)
All times are GMT -4. The time now is 05:28 AM.