.TH FORK 2
.UC 4
.SH NAME
fork \- create a child process
.SH SYNOPSIS
.nf
.B #include <unistd.h>
.B int fork(void);
.fi
.SH DESCRIPTION
.B fork() 
creates a child process the differs from the parent process only in its PID.
On success, the PID of the child process is returned in the parent's
thread of execution, and a 0 is  returned in the child's thread of execution.  
On failure, a negative value will be returned in the parent's
context and no child process will be created.
.PP
Under linux, 
.B fork()
is implemented using copy on write pages, so the only
penalty incured by fork is the time and memory required
to duplicate the parent's page tables, and to create a unique 
.B task_struct 
for the child.
.SH ERRORS
.B -EAGAIN 
is returned if 
.B fork()
cannot allocate sufficient memory to copy the parent's
page tables and allocate a 
.B task_struct
for the child.
.SH FILES
linux/kernel/fork.c
.br
/usr/include/linux/sys.h
.br
/usr/include/unistd.h
.SH SEE ALSO
exec(2)
.SH BUGS
Currently, the Linux process table is limited to 64 processes.