Cat

Cat is a command to concatenate or just print files.. here is an example

cat SHH.yt | head

which would pipe the file SHH.yt to the program head.

An example improved cat would the following shell syntax:

#!/bin/sh

while : ; do
 read i
 echo $i
done

The above serves as a rudamentary cat, when it's missing in a s(h)y[st]em.