UUOC (from comp.unix.shell on Usenet) stands for "Useless Use of cat"; the reference is to the Unix command cat(1), not the feline animal. As received wisdom on comp.unix.shell observes, "The purpose of cat is to concatenate (or 'catenate') files. If it's only one file, concatenating it with nothing at all is a waste of time, and costs you a process." Nevertheless one sees people doing
cat file | some_command and its args ...
instead of the equivalent and cheaper
<file some_command and its args ...
from Wikipedia:Cat (Unix)
also see: cat