pid — Retrieve process identifiers
If the fileId argument is given then it should normally
refer to a process pipeline created with the open command.
In this case the pid command will return a list whose elements
are the process identifiers of all the processes in the pipeline,
The list will be empty if fileId refers to an open file
that is not a process pipeline.
If no fileId argument is given then pid returns the process
identifier of the current process.
All process identifiers are returned as decimal strings.
Print process information about the processes in a pipeline using the
SysV ps program before reading the output of that pipeline:
set pipeline [open "| zcat somefile.gz | grep foobar | sort -u"]
# Print process information
exec ps -fp [pid $pipeline] >@stdout
# Print a separator and then the output of the pipeline
puts [string repeat - 70]
puts [read $pipeline]
file, pipeline, process identifier
Copyright © 1993 The Regents of the University of California.
Copyright © 1994-1996 Sun Microsystems, Inc.