Having found "anomalous results" when using FINDSTR to compare two (sorted) files with userids in them, one per line, and trying to output a third file which contains all the userids which ARE in FILEONE but ARE NOT in FILETWO: <pre>FINDSTR /I /V /L /B /G:FILETWO FILEONE > IN_FILEONE_NOT_IN_FILETWO</pre>

I'm looking for a utility which will WORK RELIABLY for files with about 2500-ish userids in each. Nothing complicated, you might say! (FINDSTR works quite well using this form with fairly small files...)

I've looked at the Unix-to-Windows port of COMM (which gives EXACTLY what I DON'T want, those lines which are COMMON to FILEONE and FILETWO)
and DIFF (the syntax of whose switches is so impenetrable that you need to have years of Unix "training" to understand the sheer obfuscatory nature thereof).

Has anyone any good suggestions for me, please? And, as always, <big><font color=blue>Command Line</font color=blue></big>. not GUI - thanks!

PS Sorry about the CAPITALS, but I've been fighting this for two days now...