]>
Commit | Line | Data |
---|---|---|
fea681da | 1 | .\" Copyright (c) 1999 Andries Brouwer (aeb@cwi.nl), 1 Nov 1999 |
9a95dcb6 | 2 | .\" and Copyright 2006, 2012, 2017 Michael Kerrisk <mtk.manpages@gmail.com> |
fea681da | 3 | .\" |
93015253 | 4 | .\" %%%LICENSE_START(VERBATIM) |
fea681da MK |
5 | .\" Permission is granted to make and distribute verbatim copies of this |
6 | .\" manual provided the copyright notice and this permission notice are | |
7 | .\" preserved on all copies. | |
8 | .\" | |
9 | .\" Permission is granted to copy and distribute modified versions of this | |
10 | .\" manual under the conditions for verbatim copying, provided that the | |
11 | .\" entire resulting derived work is distributed under the terms of a | |
12 | .\" permission notice identical to this one. | |
c13182ef | 13 | .\" |
fea681da MK |
14 | .\" Since the Linux kernel and libraries are constantly changing, this |
15 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
16 | .\" responsibility for errors or omissions, or for damages resulting from | |
17 | .\" the use of the information contained herein. The author(s) may not | |
18 | .\" have taken the same level of care in the production of this manual, | |
19 | .\" which is licensed free of charge, as they might when working | |
20 | .\" professionally. | |
c13182ef | 21 | .\" |
fea681da MK |
22 | .\" Formatted or processed versions of this manual, if unaccompanied by |
23 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 24 | .\" %%%LICENSE_END |
fea681da MK |
25 | .\" |
26 | .\" 1999-11-10: Merged text taken from the page contributed by | |
27 | .\" Reed H. Petty (rhp@draper.net) | |
28 | .\" | |
4b8c67d9 | 29 | .TH VFORK 2 2017-09-15 "Linux" "Linux Programmer's Manual" |
fea681da MK |
30 | .SH NAME |
31 | vfork \- create a child process and block parent | |
32 | .SH SYNOPSIS | |
33 | .B #include <sys/types.h> | |
34 | .br | |
35 | .B #include <unistd.h> | |
68e4db0a | 36 | .PP |
fea681da | 37 | .B pid_t vfork(void); |
68e4db0a | 38 | .PP |
cc4615cc MK |
39 | .in -4n |
40 | Feature Test Macro Requirements for glibc (see | |
41 | .BR feature_test_macros (7)): | |
42 | .in | |
68e4db0a | 43 | .PP |
cc4615cc | 44 | .BR vfork (): |
2df50e3d MK |
45 | .ad l |
46 | .RS 4 | |
47 | .PD 0 | |
48 | .TP 4 | |
49 | Since glibc 2.12: | |
50 | .nf | |
f8619b6a MK |
51 | (_XOPEN_SOURCE\ >=\ 500) && ! (_POSIX_C_SOURCE\ >=\ 200809L) |
52 | || /* Since glibc 2.19: */ _DEFAULT_SOURCE | |
53 | || /* Glibc versions <= 2.19: */ _BSD_SOURCE | |
2df50e3d MK |
54 | .TP 4 |
55 | .fi | |
56 | Before glibc 2.12: | |
cf7fa0a1 MK |
57 | _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 |
58 | .\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED | |
2df50e3d MK |
59 | .PD |
60 | .RE | |
61 | .ad b | |
8c87824d | 62 | .SH DESCRIPTION |
73d8cece | 63 | .SS Standard description |
f9f81237 | 64 | (From POSIX.1) |
fea681da | 65 | The |
bed66765 | 66 | .BR vfork () |
fea681da | 67 | function has the same effect as |
0bfa087b | 68 | .BR fork (2), |
d9bfdb9c | 69 | except that the behavior is undefined if the process created by |
bed66765 | 70 | .BR vfork () |
c13182ef MK |
71 | either modifies any data other than a variable of type |
72 | .I pid_t | |
70cbdedf | 73 | used to store the return value from |
bed66765 | 74 | .BR vfork (), |
fea681da | 75 | or returns from the function in which |
bed66765 | 76 | .BR vfork () |
fea681da | 77 | was called, or calls any other function before successfully calling |
0bfa087b | 78 | .BR _exit (2) |
fea681da | 79 | or one of the |
d806e103 | 80 | .BR exec (3) |
fea681da | 81 | family of functions. |
73d8cece | 82 | .SS Linux description |
bed66765 | 83 | .BR vfork (), |
fea681da MK |
84 | just like |
85 | .BR fork (2), | |
86 | creates a child process of the calling process. | |
87 | For details and return value and errors, see | |
88 | .BR fork (2). | |
89 | .PP | |
bed66765 | 90 | .BR vfork () |
fea681da MK |
91 | is a special case of |
92 | .BR clone (2). | |
93 | It is used to create new processes without copying the page tables of | |
c13182ef | 94 | the parent process. |
600c9aa9 | 95 | It may be useful in performance-sensitive applications |