Function
Uses the _pchar and _mchar environment variables to split
the COMMAND into fragments.
Where _pchar is seen, the commands on either side are connected
with a PIPE: from the left side's Output() to the right side's Input().
Where _mchar is seen, the commands are executed in sequence, with
no PIPE: between them, and Input() and Output() comes from the
terminal.
Notes
The "_pchar" and "_mchar" environment variables are used to determine
where to split the command, and what action to perform.
If "_pchar" is not defined, "|" is used by default. A defined value
overrides the default, and an empty value disables pipe splitting.
"_mchar" has no default.