About Us Documentation

Contact Site Map




Tcl_DetachPids(3)    Tcl Library Procedures



Tcl_DetachPids, Tcl_ReapDetachedProcs - manage child processes in background


#include <tcl.h> Tcl_DetachPids(numPids, pidPtr) Tcl_ReapDetachedProcs()


int numPids (in) Number of process ids contained in the array pointed to by pidPtr. int *pidPtr (in) Address of array containing numPids process ids. _________________________________________________________________


Tcl_DetachPids and Tcl_ReapDetachedProcs 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 waitpid 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. Tcl_DetachPids may be called to ask Tcl to take responsibil- ity for one or more processes whose process ids are con- tained in the pidPtr 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. Tcl_ReapDetachedProcs invokes the waitpid 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, Tcl_ReapDetachedProcs doesn't wait for it to exit; it will check again the next time it is invoked. Tcl automati- cally calls Tcl_ReapDetachedProcs each time the exec command is executed, so in most cases it isn't necessary for any code outside of Tcl to invoke Tcl_ReapDetachedProcs. How- ever, if you call Tcl_DetachPids in situations where the exec command may never get executed, you may wish to call Tcl_ReapDetachedProcs from time to time so that background Tcl 1 Tcl_DetachPids(3) Tcl Library Procedures processes can be cleaned up.


background, child, detach, process, wait Tcl 2 Prepared by Ready-to-Run Software, Inc.


Email addresses listed on this site may  NOT be used for unsolicited commercial email.

Ready-to-Run Software, Inc Privacy Statement

Portions (c)Copyright, 1996-2005 by Ready-to-Run Software, Inc
(All rights reserved.)
212 Cedar Cove
Lansing, NY 14882
Phone: 607 533 UNIX (8649)
Fax: 607 533 4002

To return to the Ready-to-Run Software WinPak Table of contents please presshere