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32 .\" @(#)fork.2 8.1 (Berkeley) 6/4/93
33 .\" $FreeBSD: src/lib/libc/sys/fork.2,v 1.9.2.6 2002/07/30 19:04:25 silby Exp $
40 .Nd create a new process
50 causes creation of a new process.
51 The new process (child process) is an exact copy of the
52 calling process (parent process) except for the following:
53 .Bl -bullet -offset indent
55 The child process has a unique process ID.
57 The child process has a different parent
58 process ID (i.e., the process ID of the parent process).
60 The child process has its own copy of the parent's descriptors.
61 These descriptors reference the same underlying objects, so that,
62 for instance, file pointers in file objects are shared between
63 the child and the parent, so that an
65 on a descriptor in the child process can affect a subsequent
70 This descriptor copying is also used by the shell to
71 establish standard input and output for newly created processes
72 as well as to set up pipes.
74 The child process' resource utilizations
78 All interval timers are cleared; see
82 Upon successful completion,
85 of 0 to the child process and returns the process ID of the child
86 process to the parent process. Otherwise, a value of -1 is returned
87 to the parent process, no child process is created, and the global
90 is set to indicate the error.
93 will fail and no child process will be created if:
96 The system-imposed limit on the total
97 number of processes under execution would be exceeded.
98 The limit is given by the
102 (The limit is actually ten less than this
103 except for the super user).
105 The user is not the super user, and
106 the system-imposed limit
107 on the total number of
108 processes under execution by a single user would be exceeded.
109 The limit is given by the
112 .Dv KERN_MAXPROCPERUID .
114 The user is not the super user, and
115 the soft resource limit corresponding to the resource parameter
117 would be exceeded (see
120 There is insufficient swap space for the new process.
132 function call appeared in