# pid - Retrieve process id(s)

## SYNOPSIS

pid ?fileId?

## DESCRIPTION

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, in order. The list will be empty if fileId refers to an open file that isn't 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.

## KEYWORDS

file, pipeline, process identifier