http://www.purl.org/tcl/home/man/tcl8.4/TclCmd/pid.htm 

    :   '''pid''' ?''channel''?

Returns the process ID of the current process, or the process IDs of the programs running in the pipeline (created by [open]) that ''channel'' “names”.

This command can be very useful when you have used [open] to open
a pipeline command - you can then get the process id to do a kill, etc.


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[Tcl syntax]
- [Arts and crafts of Tcl-Tk programming]
%| [Category Command] | [Category Channel] | [Category Interprocess Communication] |%
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