Match cracked password with original username in file

[Snoopy]

you need to specify hashmode (example md5) and outfileformat, oel.txt contains username:md5(öl)
BEWARE: if you use another potfile than hashcat.potfile you have to specify this too, option: --potfile-path

hashcat --show -m0 --username --outfile-format 2 oel.txt

output
username:öl