You can use $script(filename) to determine if a script is loaded or not.

if ($script(myscript.mrc) != $null) echo myscript.mrc is loaded
else echo myscript.mrc is NOT loaded


You could also test than an alias within the script file exists.

if ($isalias(myalias).fname) echo myalias exists in $v1
else echo myalias doesn't exist

-genius_at_work