2024-05-27 16:13:40 +02:00
|
|
|
'\"
|
|
|
|
|
'\" Copyright (c) 1989-1993 The Regents of the University of California.
|
2024-05-27 16:40:40 +02:00
|
|
|
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
|
2024-05-27 16:13:40 +02:00
|
|
|
'\"
|
2024-05-27 16:40:40 +02:00
|
|
|
'\" See the file "license.terms" for information on usage and redistribution
|
|
|
|
|
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
|
2024-05-27 16:13:40 +02:00
|
|
|
'\"
|
2024-05-27 16:40:40 +02:00
|
|
|
'\" SCCS: @(#) DetachPids.3 1.15 96/08/26 12:59:44
|
2024-05-27 16:13:40 +02:00
|
|
|
'\"
|
|
|
|
|
.so man.macros
|
2024-05-27 16:40:40 +02:00
|
|
|
.TH Tcl_DetachPids 3 "" Tcl "Tcl Library Procedures"
|
2024-05-27 16:13:40 +02:00
|
|
|
.BS
|
|
|
|
|
.SH NAME
|
|
|
|
|
Tcl_DetachPids, Tcl_ReapDetachedProcs \- manage child processes in background
|
|
|
|
|
.SH SYNOPSIS
|
|
|
|
|
.nf
|
|
|
|
|
\fB#include <tcl.h>\fR
|
|
|
|
|
.sp
|
|
|
|
|
\fBTcl_DetachPids\fR(\fInumPids, pidPtr\fR)
|
|
|
|
|
.sp
|
|
|
|
|
\fBTcl_ReapDetachedProcs\fR()
|
|
|
|
|
.SH ARGUMENTS
|
|
|
|
|
.AS int *statusPtr
|
|
|
|
|
.AP int numPids in
|
|
|
|
|
Number of process ids contained in the array pointed to by \fIpidPtr\fR.
|
|
|
|
|
.AP int *pidPtr in
|
|
|
|
|
Address of array containing \fInumPids\fR process ids.
|
|
|
|
|
.BE
|
|
|
|
|
|
|
|
|
|
.SH DESCRIPTION
|
|
|
|
|
.PP
|
|
|
|
|
\fBTcl_DetachPids\fR and \fBTcl_ReapDetachedProcs\fR provide a
|
|
|
|
|
mechanism for managing subprocesses that are running in background.
|
|
|
|
|
These procedures are needed because the parent of a process must
|
|
|
|
|
eventually invoke the \fBwaitpid\fR kernel call (or one of a few other
|
|
|
|
|
similar kernel calls) to wait for the child to exit. Until the
|
|
|
|
|
parent waits for the child, the child's state cannot be completely
|
|
|
|
|
reclaimed by the system. If a parent continually creates children
|
|
|
|
|
and doesn't wait on them, the system's process table will eventually
|
|
|
|
|
overflow, even if all the children have exited.
|
|
|
|
|
.PP
|
|
|
|
|
\fBTcl_DetachPids\fR may be called to ask Tcl to take responsibility
|
|
|
|
|
for one or more processes whose process ids are contained in the
|
|
|
|
|
\fIpidPtr\fR array passed as argument. The caller presumably
|
|
|
|
|
has started these processes running in background and doesn't
|
|
|
|
|
want to have to deal with them again.
|
|
|
|
|
.PP
|
|
|
|
|
\fBTcl_ReapDetachedProcs\fR invokes the \fBwaitpid\fR kernel call
|
|
|
|
|
on each of the background processes so that its state can be cleaned
|
|
|
|
|
up if it has exited. If the process hasn't exited yet,
|
|
|
|
|
\fBTcl_ReapDetachedProcs\fR doesn't wait for it to exit; it will check again
|
|
|
|
|
the next time it is invoked.
|
|
|
|
|
Tcl automatically calls \fBTcl_ReapDetachedProcs\fR each time the
|
|
|
|
|
\fBexec\fR command is executed, so in most cases it isn't necessary
|
|
|
|
|
for any code outside of Tcl to invoke \fBTcl_ReapDetachedProcs\fR.
|
|
|
|
|
However, if you call \fBTcl_DetachPids\fR in situations where the
|
|
|
|
|
\fBexec\fR command may never get executed, you may wish to call
|
|
|
|
|
\fBTcl_ReapDetachedProcs\fR from time to time so that background
|
|
|
|
|
processes can be cleaned up.
|
|
|
|
|
|
|
|
|
|
.SH KEYWORDS
|
|
|
|
|
background, child, detach, process, wait
|
