VFORK(2) BSD Programmer's Manual VFORK(2)NAMEvfork - spawn new process and block parent
SYNOPSIS
#include <unistd.h>
pid_t
vfork(void);
DESCRIPTIONvfork() 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 ALSOexecve(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
