Character stream manipulation

Character stream manipulation is one of the key points of the UNIX philosophy. It means that you can take the output of a program and pass it as input to another program which, again, produces an output.

= Concepts =
 * piping
 * stdout, stderr and stdin
 * regex
 * ReDirecting
 * substitutIon

= Commands =
 * cat
 * cut
 * tac
 * head
 * tail
 * grep
 * wc
 * sed
 * awk
 * xargs
 * tr
 * paste
 * join
 * echo
 * read
 * yes