sed reads the standard input into the pattern space,
performs a sequence of editing commands on the pattern
space, then writes the pattern space to STDOUT.
sed is a multipurpose tool which combines the work of
several filters.
sed uses instructions to act on text.
AN instruction combines an address for selecting lines with
an action to be taken on then , as shown by the syntax
sed options 'address action' file(s)
sed reads the standard input into the pattern space,
performs a sequence of editing commands on the pattern
space, then writes the pattern space to STDOUT.