MirOS Manual: vfork(2)

VFORK(2)                   BSD Programmer's Manual                    VFORK(2)

NAME

     vfork - spawn new process and block parent

SYNOPSIS

     #include <unistd.h>

     pid_t
     vfork(void);

DESCRIPTION

     vfork() was originally used to create new processes without fully copying
     the address space of the old process, which is horrendously inefficient
     in a paged environment. It was useful when the purpose of fork(2) would
     have been to create a new system context for an execve(2). Since fork(2)
     is now efficient, even in the above case, the need for vfork() has dimin-
     ished. vfork() differs from fork(2) in that the parent is suspended until
     the child makes a call to execve(2) or an exit (either by a call to
     _exit(2) or abnormally).

     vfork() returns 0 in the child's context and (later) the PID of the child
     in the parent's context.

RETURN VALUES

     Same as for fork(2).

SEE ALSO

     execve(2), fork(2), sigaction(2), wait(2)

HISTORY

     The vfork() function call appeared in 2.9BSD.

BUGS

     To avoid a possible deadlock situation, processes that are children in
     the middle of a vfork() are never sent SIGTTOU or SIGTTIN signals; rath-
     er, output or ioctl(2) calls are allowed and input attempts result in an
     end-of-file indication.

MirOS BSD #10-current           June 30, 1997                                1

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