cat \- catenate and print
and writes it on the standard output.
concatenates the first two files and places the result on the third.
If no input file is given,
or if the argument `\-' is encountered,
Output is buffered in 512-byte blocks unless the standard
output is a terminal or the
Beware of `cat a b >a' and `cat a b >b', which destroy
the input files before reading them.