2 .\" This manual page is taken directly from Plan9, and modified to
3 .\" describe the actual BSD implementation. Permission for
4 .\" use of this page comes from Rob Pike <rob@plan9.att.com>.
13 .Nd manipulate process resources
21 Forking, vforking or rforking are the only ways new processes are created.
26 selects which resources of the
27 invoking process (parent) are shared
28 by the new process (child) or initialized to
31 the open file descriptor table (which, when shared, permits processes
32 to open and close files for other processes),
37 is the logical OR of some subset of:
38 .Bl -tag -width ".Dv RFLINUXTHPN"
40 If set a new process is created; otherwise changes affect the
43 If set, the child process will be dissociated from the parent.
45 exit the child will not leave a status for the parent to collect.
49 If set, the invoker's file descriptor table (see
51 is copied; otherwise the two processes share a
54 If set, the new process starts with a clean file descriptor table.
55 Is mutually exclusive with
58 If set, the new process shares file descriptor to process leaders table
60 Only applies when neither
66 If set, the kernel will force sharing of the entire address space,
67 typically by sharing the hardware page table directly.
69 will thus inherit and share all the segments the parent process owns,
70 whether they are normally shareable or not.
72 not split (both the parent and child return on the same stack) and thus
74 with the RFMEM flag may not generally be called directly from high level
75 languages including C.
78 A helper function is provided to assist with this problem and will cause
79 the new process to run on the provided stack.
84 If set, the kernel will force sharing the sigacts structure between the
87 If set, the kernel will return SIGUSR1 instead of SIGCHILD upon thread
89 This is intended to mimic certain Linux clone behaviour.
92 File descriptors in a shared file descriptor table are kept
93 open until either they are explicitly closed
94 or all processes sharing the table exit.
99 value returned in the parent process
101 of the child process; the value returned in the child is zero.
104 the return value is zero.
105 Process id's range from 1 to the maximum integer
111 will sleep, if necessary, until required process resources are available.
116 can be implemented as a call to
117 .Fn rfork "RFFDG | RFPROC"
118 but is not for backwards compatibility.
120 Upon successful completion,
123 of 0 to the child process and returns the process ID of the child
124 process to the parent process.
125 Otherwise, a value of -1 is returned
126 to the parent process, no child process is created, and the global
129 is set to indicate the error.
134 will fail and no child process will be created if:
137 The system-imposed limit on the total
138 number of processes under execution would be exceeded.
139 The limit is given by the
143 (The limit is actually ten less than this
144 except for the super user).
146 The user is not the super user, and
147 the system-imposed limit
148 on the total number of
149 processes under execution by a single user would be exceeded.
150 The limit is given by the
153 .Dv KERN_MAXPROCPERUID .
155 The user is not the super user, and
156 the soft resource limit corresponding to the
160 would be exceeded (see
163 Both the RFFDG and the RFCFDG flags were specified.
165 Any flags not listed above were specified.
167 There is insufficient swap space for the new process.
178 function first appeared in Plan9.
181 does not yet implement a native
183 library call, and the current pthreads implementation does not use
186 A native port of the linux threads library,
187 .Pa /usr/ports/devel/linuxthreads ,
190 call that utilizes RFMEM.
193 function can often be used instead of