Tcl_ReapDetachedProcs man page on AIX

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Tcl_DetachPids(3)	    Tcl Library Procedures	     Tcl_DetachPids(3)

______________________________________________________________________________

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

SYNOPSIS
       #include <tcl.h>

       Tcl_DetachPids(numPids, pidPtr)

       Tcl_ReapDetachedProcs()

       Tcl_Pid
       Tcl_WaitPid(pid, statusPtr, options)

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

       int options (in)			The options controlling the wait. WNO‐
					HANG specifies not to wait when check‐
					ing the process.
_________________________________________________________________

DESCRIPTION
       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
       exited.

       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  does  not	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 has not exited yet, Tcl_ReapDetachedProcs  does
       not  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 is not 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
       system.

KEYWORDS
       background, child, detach, process, wait

Tcl							     Tcl_DetachPids(3)
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