what is using a file?

are fuser and lsof similar? if so, is one more handy than the other?

can these be used to find out what is using a shared lib?

thanks

Similar in reasoning, but not in implementation or in general usage. If you know the file you are dealing with either will work, if you don't know the file but know the PID or process name then lsof is easier.

ok, thanks for that