merge - three-way file merge

SYNOPSIS

       merge  [  -L  label1  [  -L label3 ] ] [ -p ] [ -q ] file1
       file2 file3

DESCRIPTION

       merge incorporates all changes that  lead  from  file2  to
       file3  into  file1.  The result goes to standard output if
       -p is present, into file1 otherwise.  merge is useful  for
       combining  separate changes to an original.  Suppose file2
       is the original, and both file1 and  file3  are  modifica-
       tions of file2.  Then merge combines both changes.

       An  overlap occurs if both file1 and file3 have changes in
       a common segment of lines.  On a  few  older  hosts  where
       diff3  does  not  support  the  -E  option, merge does not
       detect overlaps, and merely  supplies  the  changed  lines
       from  file3.  On most hosts, if overlaps occur, merge out-
       puts a message  (unless  the  -q  option  is  given),  and
       includes  both  alternatives  in the result.  The alterna-
       tives are delimited as follows:

              <<<<<<< file1
              lines in file1
              =======
              lines in file3
              >>>>>>> file3

       If there are overlaps, the user should edit the result and
       delete  one  of  the  alternatives.   If the -L label1 and
       -L label3 options are given,  the  labels  are  output  in
       place of the names file1 and file3 in overlap reports.

DIAGNOSTICS

       Exit  status  is 0 for no overlaps, 1 for some overlaps, 2
       for trouble.

IDENTIFICATION

       Author: Walter F. Tichy.
       Revision Number: 5.3; Release Date: 1991/02/28.
       Copyright (C) 1982, 1988, 1989 by Walter F. Tichy.
       Copyright (C) 1990, 1991 by Paul Eggert.

SEE ALSO

       diff3(1), diff(1), rcsmerge(1), co(1).