Simply using cat to dump a single file to STDOUT is technically a misuse because cat is theoretically intended to concatenate files. This 'misuse' is 'solved' by bat because bat seems to be primarily intended for its syntax highlighting and git-related features; according to bat's docs, cat-style concatenation of files is intended for drop-in compatibility with traditional cat.

That said, the idea that using cat to show a single file is "misusing" cat is prescriptivist rules-lawyering. There is no technical reason against using cat for non-concatenation purposes. The descriptivist interpretation of cat says using the tool for non-concatenation purposes is fine, since that's how people are actually using it.

However, note that cat is often misused as a substitute for STDIN redirection:

    # this creates an extra process that wastes
    # time copying STDIN to STDOUT
    cat "${inputfile}" | do_stuff

    # just connect inputfile directly to STDIN
    do_stuff <"${inputfile}"

    # or if you want to keep the input
    # at the start of the pipeline
    <"${inputfile}" do_stuff

I guess the author was thinking of how cat's original purpose is to concatenate multiple files, not show just one file. (But I certainly don't think using cat in the latter way is a misuse.)

There's also a commonly noted "unnecessary use of cat" where people do this:

  cat file.txt | grep foo

instead of this:

  <file.txt grep.foo

but that's not relevant to bat (which can be used unnecessarily in the same way).

Catting a file will your terminal make interpret escape codes in the file.

For instance:

    $ echo -e "\033]0;${USER} is an unfriendly person\007" > test-file.txt

Then, many days later:

    $ cat test-file.txt

will change your terminal title.

With less, you _can_ interpret escape codes, but usually you don't, and I consider this the correct default.

They are referring to using cat to print out a file to the terminal. I'm not sure that's a "misuse", but personally I've never done it, using "more" or "less" instead. "bat" really is a replacement for more/less, only with additional features such as syntax highlighting in source code.

Using cat to catenate a file to standard input isn't misuse, but it looks like bat performs syntax highlighting.

Google "UUOC" - it's famous.

Edit: Sorry downvoter, thought I was being helpful - no-one mentioned the acronym yet. There's a lot online about it, more than I'm qualified to explain. Entertaining reading too. I remember reading about the UUOC Awards years ago..

I guess they just meant it as in "reading code," when in fact bat is better tool just for reading code.