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. It is the case that fork is now efficient, even in the above case, so that the need for vfork() is diminished. Vfork() differs from fork 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.

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

DIAGNOSTICS
Same as for fork(2).

BUGS

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

HISTORY
The vfork() function call appeared in 3.0BSD.