Tcl_ReapDetachedProcs man page on QNX

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Tcl_DetachPids(3)	    Tcl Library Procedures	     Tcl_DetachPids(3)


       Tcl_DetachPids,	Tcl_ReapDetachedProcs, Tcl_WaitPid - manage child pro‐
       cesses in background

       #include <tcl.h>

       Tcl_DetachPids(numPids, pidPtr)


       Tcl_WaitPid(pid, statPtr, options)

       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_Pid		  pid(in)   The id of the process (pipe) to wait for.

       int*  statPtr	  (out)	    The result of waiting on a process (pipe).
				    Either 0 or ECHILD.

       int   options		    The	 options controlling the wait. WNOHANG
				    specifies not to wait  when	 checking  the

       Tcl_DetachPids and Tcl_ReapDetachedProcs provide a mechanism for manag‐
       ing subprocesses that are running in background.	 These procedures  are
       needed because the parent of a process must eventually invoke the wait‐
       pid 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  par‐
       ent continually creates children and doesn't wait on them, the system's
       process table will eventually overflow, even if all the	children  have

       Tcl_DetachPids  may be called to ask Tcl to take responsibility for one
       or more processes whose process ids are contained 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 automatically 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.  However,  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 processes can be cleaned up.

       Tcl_WaitPid  is	a  thin	 wrapper around the facilities provided by the
       operating system to wait on the end of a spawned process and to check a
       whether	spawned	 process  is  still running. It is used by Tcl_ReapDe‐
       tachedProcs and the channel system to  portably	access	the  operating

       background, child, detach, process, wait

Tcl							     Tcl_DetachPids(3)
                             _         _         _ 
                            | |       | |       | |     
                            | |       | |       | |     
                         __ | | __ __ | | __ __ | | __  
                         \ \| |/ / \ \| |/ / \ \| |/ /  
                          \ \ / /   \ \ / /   \ \ / /   
                           \   /     \   /     \   /    
                            \_/       \_/       \_/ 
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