distrib/share/tcl/help/tcl/processes/pid

   1 NAME
   2        pid - Retrieve process identifiers
   3
   4 SYNOPSIS
   5        pid ?fileId?
   6
   7
   8 DESCRIPTION
   9        If  the  fileId  argument  is  given then it should normally refer to a
  10        process pipeline created with the open command.  In this case  the  pid
  11        command  will  return a list whose elements are the process identifiers
  12        of all the processes in the pipeline, in order.  The list will be empty
  13        if  fileId refers to an open file that isn't a process pipeline.  If no
  14        fileId argument is given then pid returns the process identifier of the
  15        current  process.   All  process  identifiers  are  returned as decimal
  16        strings.
  17
  18 EXAMPLE
  19        Print process information about the processes in a pipeline  using  the
  20        SysV ps program before reading the output of that pipeline:
  21
  22               set pipeline [open "| zcat somefile.gz | grep foobar | sort -u"]
  23               # Print process information
  24               exec ps -fp [pid $pipeline] >@stdout
  25               # Print a separator and then the output of the pipeline
  26               puts [string repeat - 70]
  27               puts [read $pipeline]
  28               close $pipeline
  29
  30
  31 SEE ALSO
  32        exec(n), open(n)
  33
  34
  35 KEYWORDS