VFORK(2) BSD Programmer's Manual VFORK(2)
vfork - spawn new process and block parent
#include <unistd.h> pid_t vfork(void);
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.
Same as for fork(2).
execve(2), fork(2), sigaction(2), wait(2)
The vfork() function call appeared in 2.9BSD.
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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