The
canonical search and replace operator, as used in
sed,
Perl,
and any other tool that makes use of
regular expressions.
s/pattern/replacement/
Any valid regular expression may be sought as
pattern. If the s/// operator is followed by g, all occurrences of the pattern are replaced, instead of just the first found; if followed by i, the matching is case-insensitive.
A full discussion of the syntax of s/// is beyond the scope of this writeup, and may be better served by the Perl manual, or the excellent O'Reilly book Mastering Regular Expressions.
The s/// form is often seen in text-based chat environments, where it is used to correct typos in one's previous statements, or humorously in the same manner ^H often is.