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28 .\" @(#)fork.2 8.1 (Berkeley) 6/4/93
29 .\" $FreeBSD: src/lib/libc/sys/fork.2,v 1.9.2.6 2002/07/30 19:04:25 silby Exp $
30 .\" $DragonFly: src/lib/libc/sys/fork.2,v 1.2 2003/06/17 04:26:47 dillon Exp $
37 .Nd create a new process
47 causes creation of a new process.
48 The new process (child process) is an exact copy of the
49 calling process (parent process) except for the following:
50 .Bl -bullet -offset indent
52 The child process has a unique process ID.
54 The child process has a different parent
55 process ID (i.e., the process ID of the parent process).
57 The child process has its own copy of the parent's descriptors.
58 These descriptors reference the same underlying objects, so that,
59 for instance, file pointers in file objects are shared between
60 the child and the parent, so that an
62 on a descriptor in the child process can affect a subsequent
67 This descriptor copying is also used by the shell to
68 establish standard input and output for newly created processes
69 as well as to set up pipes.
71 The child process' resource utilizations
75 All interval timers are cleared; see
79 Upon successful completion,
82 of 0 to the child process and returns the process ID of the child
83 process to the parent process. Otherwise, a value of -1 is returned
84 to the parent process, no child process is created, and the global
87 is set to indicate the error.
90 will fail and no child process will be created if:
93 The system-imposed limit on the total
94 number of processes under execution would be exceeded.
95 The limit is given by the
99 (The limit is actually ten less than this
100 except for the super user).
102 The user is not the super user, and
103 the system-imposed limit
104 on the total number of
105 processes under execution by a single user would be exceeded.
106 The limit is given by the
109 .Dv KERN_MAXPROCPERUID .
111 The user is not the super user, and
112 the soft resource limit corresponding to the resource parameter
114 would be exceeded (see
117 There is insufficient swap space for the new process.
129 function call appeared in