After the optional word designator, you can add a sequence of one or more
of the following modifiers, each preceded by a :.
h
t
r
.suffix, leaving
the basename.
e
p
s/old/new/
/.
The delimiter may be quoted in old and new
with a single backslash. If & appears in new,
it is replaced by old. A single backslash will quote
the &. The final delimiter is optional if it is the last
character on the input line.
&
g
s, as in gs/old/new/,
or with &.