Try not giving it a literal location. Just try "cheat" and see if that helps. Is this other .ini you mentioned above possibly influencing the settings? Someone who is familiar with linux folder structure might need to help further.
no. i already mentioned that i deleted the other one. although, for future reference, my frontend (QMC2) does have (by default) some of the same settings in its own ini file as mame's ini which was confusing before i realized it. (and yes it is pointed to the correct path and cheats are enabled in QMC2's ini file).
after reading your suggestion, i remembered that my mame package (from the Packman repository) has a default directory structure (just like it has a default ini file):
rpm -q -l mame
/etc/mame
/etc/mame/mame.ini <-- (this is the conflicting ini i deleted)
/usr/bin/mame
/usr/share/doc/packages/mame
/usr/share/doc/packages/mame/docs
/usr/share/doc/packages/mame/docs/config.txt
/usr/share/doc/packages/mame/docs/license.txt
/usr/share/doc/packages/mame/docs/mame.txt
/usr/share/doc/packages/mame/docs/newvideo.txt
/usr/share/doc/packages/mame/docs/windows.txt
/usr/share/doc/packages/mame/whatsnew.txt
/usr/share/mame
/usr/share/mame/artwork
/usr/share/mame/chds
/usr/share/mame/cheats
/usr/share/mame/crosshair
/usr/share/mame/ctrlr
/usr/share/mame/effects
/usr/share/mame/fonts
/usr/share/mame/keymaps
/usr/share/mame/roms
/usr/share/mame/samples
/usr/share/man/man6/mame.6.gz
if i take your suggestion, won't it just point it to the (empty) directory in bold above? (i keep the files that would go in those directories in my mame directory in ~/).