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28 .\" @(#)vfork.2 8.1 (Berkeley) 6/4/93
36 .Nd create a new process without copying the address space
47 can be used to create new processes without fully copying the address
48 space of the old process, which is horrendously inefficient in a paged
50 It is useful when the purpose of
52 would have been to create a new system context for an
59 in that the child borrows the parent's memory and thread of
60 control until a call to
62 or an exit (either by a call to
65 The parent process is suspended while the child is using its resources.
70 returns 0 in the child's context and (later) the pid of the child in
76 can normally be used just like
78 It does not work, however, to return while running in the child's context
79 from the procedure that called
81 since the eventual return from
83 would then return to a no longer existent stack frame.
84 Be careful, also, to call
92 will flush and close standard I/O channels, and thereby mess up the
93 parent processes standard I/O data structures.
98 since buffered data would then be flushed twice.)
113 system call appeared in
116 To avoid a possible deadlock situation,
117 processes that are children in the middle
129 and input attempts result in an end-of-file indication.