FORK(2)                             Linux Programmer's Manual                             FORK(2)



NAME
       fork - create a child process

SYNOPSIS
       #include <sys/types.h>
       #include <unistd.h>

       pid_t fork(void);

DESCRIPTION
       fork  creates  a  child  process  that differs from the parent process only in its PID and
       PPID, and in the fact that resource utilizations are set to 0.   File  locks  and  pending
       signals are not inherited.

       Under  Linux,  fork is implemented using copy-on-write pages, so the only penalty incurred
       by fork is the time and memory required to duplicate the parent's page tables, and to cre-
       ate a unique task structure for the child.

RETURN VALUE
       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 -1 will be returned
       in the parent's context, no child process will be created, and errno will be set appropri-
       ately.

ERRORS
       EAGAIN fork cannot allocate sufficient memory to copy the parent's page tables  and  allo-
              cate a task structure for the child.

       ENOMEM fork failed to allocate the necessary kernel structures because memory is tight.

CONFORMING TO
       The fork call conforms to SVr4, SVID, POSIX, X/OPEN, BSD 4.3.

SEE ALSO
       clone(2), execve(2), vfork(2), wait(2)



Linux 1.2.9                                 1995-06-10                                    FORK(2)