considered harmful

http://harmful.cat-v.org/software/
>2013
>using harmful software

>>148

Also, looking at the various cat sources: https://gist.github.com/pete/665971

Only the original UNIXv7 cat ever set a buffer, with setbuf(stdout, stdbuf).

BSD cat uses -u to set the buffer to NULL, but in the code there it doesn't ever seem to set the buffer otherwise, so it's likely always unbuffered, or buffered to the kernel's discretion.