This is documentation for Mathematica 4, which was
based on an earlier version of the Wolfram Language.
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$MachineDomain$ProcessID

$UserName

FilledSmallSquare$UserName gives the login name of the user who invoked the Mathematica kernel, as recorded by the operating system.

FilledSmallSquare On Unix and similar operating systems, $UserName is derived from the UID associated with the Mathematica kernel process.

FilledSmallSquare On operating systems where no login name can be found, $UserName is None.

FilledSmallSquare See The Mathematica Book: Section 2.13.5.

FilledSmallSquare See also: $HomeDirectory, Environment.

$MachineDomain$ProcessID