2 '\" Copyright (c) 1989-1993 The Regents of the University of California.
3 '\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
5 '\" See the file "license.terms" for information on usage and redistribution
6 '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
8 '\" RCS: @(#) $Id: DetachPids.3,v 1.3 2001/04/03 14:53:45 andreas_kupries Exp $
10 '\" The definitions below are for supplemental macros used in Tcl/Tk
13 '\" .AP type name in/out ?indent?
14 '\" Start paragraph describing an argument to a library procedure.
15 '\" type is type of argument (int, etc.), in/out is either "in", "out",
16 '\" or "in/out" to describe whether procedure reads or modifies arg,
17 '\" and indent is equivalent to second arg of .IP (shouldn't ever be
18 '\" needed; use .AS below instead)
21 '\" Give maximum sizes of arguments for setting tab stops. Type and
22 '\" name are examples of largest possible arguments that will be passed
23 '\" to .AP later. If args are omitted, default tab stops are used.
26 '\" Start box enclosure. From here until next .BE, everything will be
27 '\" enclosed in one large box.
30 '\" End of box enclosure.
33 '\" Begin code excerpt.
38 '\" .VS ?version? ?br?
39 '\" Begin vertical sidebar, for use in marking newly-changed parts
40 '\" of man pages. The first argument is ignored and used for recording
41 '\" the version when the .VS was added, so that the sidebars can be
42 '\" found and removed when they reach a certain age. If another argument
43 '\" is present, then a line break is forced before starting the sidebar.
46 '\" End of vertical sidebar.
49 '\" Begin an indented unfilled display.
52 '\" End of indented unfilled display.
55 '\" Start of list of standard options for a Tk widget. The
56 '\" options follow on successive lines, in four columns separated
60 '\" End of list of standard options for a Tk widget.
62 '\" .OP cmdName dbName dbClass
63 '\" Start of description of a specific option. cmdName gives the
64 '\" option's name as specified in the class command, dbName gives
65 '\" the option's name in the option database, and dbClass gives
66 '\" the option's class in the option database.
69 '\" Print arg1 underlined, then print arg2 normally.
71 '\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $
73 '\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
77 '\" # Start an argument description
81 . ie !"\\$2"" .TP \\n()Cu
86 \&\\$1 \\fI\\$2\\fP (\\$3)
99 '\" # define tabbing values for .AP
102 .if !"\\$1"" .nr )A \\w'\\$1'u+3n
105 .if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
106 .nr )C \\n()Bu+\\w'(in/out)'u+2n
108 .AS Tcl_Interp Tcl_CreateInterp in/out
109 '\" # BS - start boxed text
110 '\" # ^y = starting y location
118 .if n \l'\\n(.lu\(ul'
121 '\" # BE - end boxed text (draw box now)
126 .ie n \l'\\n(^lu\(ul'
128 .\" Draw four-sided box normally, but don't draw top of
129 .\" box if the box started on an earlier page.
131 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
134 \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
141 '\" # VS - start vertical sidebar
142 '\" # ^Y = starting y location
143 '\" # ^v = 1 (for troff; for nroff this doesn't matter)
147 .ie n 'mc \s12\(br\s0
150 '\" # VE - end of vertical sidebar
158 \h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n'
165 '\" # Special macro to handle page bottom: finish off current
166 '\" # box/sidebar if in box/sidebar mode, then invoked standard
167 '\" # page bottom macro.
174 .\" Draw three-sided box if this is the box's first page,
175 .\" draw two sides but no top otherwise.
176 .ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
177 .el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
180 .nr ^x \\n(^tu+1v-\\n(^Yu
181 \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
194 '\" # DS - begin display
200 '\" # DE - end display
206 '\" # SO - start of list of standard options
208 .SH "STANDARD OPTIONS"
214 '\" # SE - end of list of standard options
219 See the \\fBoptions\\fR manual entry for details on the standard options.
221 '\" # OP - start of full description for a single option
226 Command-Line Name: \\fB\\$1\\fR
227 Database Name: \\fB\\$2\\fR
228 Database Class: \\fB\\$3\\fR
232 '\" # CS - begin code excerpt
238 '\" # CE - end code excerpt
246 .TH Tcl_DetachPids 3 "" Tcl "Tcl Library Procedures"
249 Tcl_DetachPids, Tcl_ReapDetachedProcs, Tcl_WaitPid \- manage child processes in background
252 \fB#include <tcl.h>\fR
254 \fBTcl_DetachPids\fR(\fInumPids, pidPtr\fR)
256 \fBTcl_ReapDetachedProcs\fR()
259 \fBTcl_WaitPid\fR(\fIpid, statPtr, options\fR)
263 Number of process ids contained in the array pointed to by \fIpidPtr\fR.
265 Address of array containing \fInumPids\fR process ids.
267 The id of the process (pipe) to wait for.
269 The result of waiting on a process (pipe). Either 0 or ECHILD.
271 The options controlling the wait. WNOHANG specifies not to wait when
272 checking the process.
276 \fBTcl_DetachPids\fR and \fBTcl_ReapDetachedProcs\fR provide a
277 mechanism for managing subprocesses that are running in background.
278 These procedures are needed because the parent of a process must
279 eventually invoke the \fBwaitpid\fR kernel call (or one of a few other
280 similar kernel calls) to wait for the child to exit. Until the
281 parent waits for the child, the child's state cannot be completely
282 reclaimed by the system. If a parent continually creates children
283 and doesn't wait on them, the system's process table will eventually
284 overflow, even if all the children have exited.
286 \fBTcl_DetachPids\fR may be called to ask Tcl to take responsibility
287 for one or more processes whose process ids are contained in the
288 \fIpidPtr\fR array passed as argument. The caller presumably
289 has started these processes running in background and doesn't
290 want to have to deal with them again.
292 \fBTcl_ReapDetachedProcs\fR invokes the \fBwaitpid\fR kernel call
293 on each of the background processes so that its state can be cleaned
294 up if it has exited. If the process hasn't exited yet,
295 \fBTcl_ReapDetachedProcs\fR doesn't wait for it to exit; it will check again
296 the next time it is invoked.
297 Tcl automatically calls \fBTcl_ReapDetachedProcs\fR each time the
298 \fBexec\fR command is executed, so in most cases it isn't necessary
299 for any code outside of Tcl to invoke \fBTcl_ReapDetachedProcs\fR.
300 However, if you call \fBTcl_DetachPids\fR in situations where the
301 \fBexec\fR command may never get executed, you may wish to call
302 \fBTcl_ReapDetachedProcs\fR from time to time so that background
303 processes can be cleaned up.
305 \fBTcl_WaitPid\fR is a thin wrapper around the facilities provided by
306 the operating system to wait on the end of a spawned process and to
307 check a whether spawned process is still running. It is used by
308 \fBTcl_ReapDetachedProcs\fR and the channel system to portably access
309 the operating system.
312 background, child, detach, process, wait