The "isin" statement is to check whether a partial string is inside a full string, i.e. if (a isin abc)..

To check whether a string is in a file you can use $read

for example..

if ($read(files\test.txt,w,$+(*,$did(4).text,*)) { Your Command }

Will return the first result in a search for *STRING* in a file however a better parameter than 'w' to use might be 's' depending on whether you have 1 nickname per line, if so use..

if ($read(files\test.txt,s,$did(4).text) { Your Command }

If 'w' or 's' parameter isnt to your liking you may have to loop the file looking for an exact match in which case..

var %i $lines(C:\test.txt) | var %t 0 | while (%i) { if ($read(C:\test.txt,%i) == $did(4).text) { var %t 1 } | dec %i } | if (%t == 1) { echo ALREADY EXISTS } | else { echo DOESNT EXIST }

Replacing echo ALREADY EXISTS and echo DOESNT EXIST with whatever you may.

For more information /help $read if you require it.

Hope this Helps.