$alias
From Scriptwiki
Returns the filename for the Nth loaded alias file.
$alias(N/filename)
If you specify a filename, it returns $null if the file isn't loaded.
Example
$alias(0) returns the number of alias files loaded $alias(2) returns the filename of the 2nd loaded alias file $alias(moo.txt) returns $null if the file isn't loaded, or moo.txt if it is.