sed は s///だけでも

IT 
s/regexp/replacement/
       Attempt to match regexp against the pattern space.  If success-
       ful,  replace  that  portion  matched  with  replacement.   The
       replacement may contain the special character  &  to  refer  to
       that  portion  of the pattern space which matched, and the spe-
       cial escapes \1 through \9 to refer to the corresponding match-
       ing sub-expressions in the regexp.