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DIFF3(1)                     BSD Reference Manual                     DIFF3(1)

NAME
     diff3 - 3-way differential file comparison

SYNOPSIS
     diff3 [-exEX3] file1 file2 file3

DESCRIPTION
     The diff3 utility compares the contents of three different versions of a
     file, file1, file2 and file3, writing the result to the standard output.
     The options describe different methods of merging and purging the sepa-
     rate versions into a new file.  Diff3 is used by RCS(1) to merge specific
     versions or create new versions.

     Options are:

     -e        Produces output in a form suitable as an input script for the
               ed(1) utility.  The script may then be used to merge differ-
               ences common between all three files and differences specific
               to file1 and file3.  In other words, the -e option ignores dif-
               ferences specific to file1 and file2, and those specific to
               file2 and file3.  It is useful for backing out changes specific
               to file2 only.

     -x        Produces an output script suitable for ed(1) with changes spe-
               cific only to all three versions.

     -3        Produces an output script suitable for ed(1) with changes spe-
               cific only to file3.

     -E, -X    Similar to -e and -x, respectively, but treat overlapping
               changes (i.e., changes that would be noted with ==== in the
               normal listing) differently.  The overlapping lines from both
               files will be inserted by the edit script, bracketed by
               "<<<<<<" and ">>>>>>" lines.

     The -E option is used by RCS merge(1) to insure that overlapping changes
     in the merged files are preserved and brought to someone's attention.

     For example, suppose lines 7-8 are changed in both file1 and file2.  Ap-
     plying the edit script generated by the command

           diff3 -E file1 file2 file3

     to file1 results in the file:

           lines 1-6
           of file1
           <<<<<<< file1
           lines 7-8
           of file1
           =======
           lines 7-8
           of file3
           >>>>>>> file3
           rest of file1

     The default output of diff3 makes notation of the differences between all
     files, and those differences specific to each pair of files. The changes
     are described by the commands necessary for ed(1) to create the desired
     target from the different versions.  See diff(1) for a description of the
     commands.

     ====   The lines beneath this notation are ranges of lines which are dif-

            ferent between all files.

     ====n  The lines beneath this notation are ranges of lines which are ex-
            clusively different in file n.

FILES
     /tmp/d3?????    temporary files.
     /usr/bin/diff3  the executable.

SEE ALSO
     diff(1) ed(1) rcs(1)

BUGS
     The -e option cannot catch and change lines which have `.' as the first
     and only character on the line.  The resulting script will fail on that
     line as `.' is an ed(1) editing command.

HISTORY
     A diff3 command appeared in Version 7 AT&T UNIX.

4.3-Reno Berkeley Distribution  April 18, 1994                               2