I thought you might be interested in this: I just released "enctool", which will guess and verify files' encodings. For example, to test whether a file which you know contains Cyrillic characters is encoded in UTF-8 or KOI8-R: enctool --encodings=UTF-8,KOI8-R --one-of='\p{Script=Cyrillic}' filename.txt (there are lots of other options too, see the POD - in this case, e.g. --test-all --list-chars --extra-verbose might also be interesting). Although there are tests, I rewrote it pretty much from scratch from an earlier version, so I've still labeled it beta - if there are issues, let me know.

Update: If you work with KOI8-R a lot, you might want to change the default list of encodings, for example, one way is to put this in your ~/.profile: export ENCTOOL_ENCODINGS="ASCII,UTF-8,KOI8-R,Latin1,CP1252"