[address] s [/ pattern / replacement /] [options] [count]
Replace each instance of pattern on the specified lines with replacement. If pattern and replacement are omitted, repeat last substitution. count specifies the number of lines on which to substitute, starting with address. When preceded by the global (g) or v command, this command can be specified with a blank pattern, in which case the pattern from the g or v command is then used. For more examples, see Section 9.4.1 in Chapter 9.
Prompt for confirmation before each change.
Substitute all instances of pattern on each line.
Print the last line on which a substitution was made.
1,10s/yes/no/gSubstitute on first 10 lines :
%s/[Hh]ello/Hi/gcConfirm global substitutions :
s/Fortran/\U&/ 3Uppercase first instance of "Fortran" on next three lines :
g/^[0-9][0-9]*/s//Line &:/For every line beginning with one or more digits, add the "Line" and a colon