DIFF3(1)							      DIFF3(1)

NAME    [Toc]    [Back]

     diff3 - 3-way differential	file comparison

SYNOPSIS    [Toc]    [Back]

     diff3 [ -exEX3 [-i	| -m] [-L label1 -L label3] ] file1 file2 file3

DESCRIPTION    [Toc]    [Back]

     Diff3 compares three versions of a	file, and publishes disagreeing	ranges
     of	text flagged with these	codes:

     ====	     all three files differ

     ====1	     file1 is different

     ====2	     file2 is different

     ====3	     file3 is different

     The type of change	suffered in converting a given range of	a given	file
     to	some other is indicated	in one of these	ways:

     f : n1 a	     Text is to	be appended after line number n1 in file f,
		     where f = 1, 2, or	3.

     f : n1 , n2 c   Text is to	be changed in the range	line n1	to line	n2.
		     If	n1 = n2, the range may be abbreviated to n1.

     The original contents of the range	follows	immediately after a c
     indication.  When the contents of two files are identical,	the contents
     of	the lower-numbered file	is suppressed.

     The -m option produces a merge script on the output of diff3.  If none of
     -eExX3 is specified along with -m,	then the format	of option -E is
     presumed.	If the -m option is used, then binary files, files without
     trailing newline, and files with excessively long lines can be
     successfully merged.

     If	no -m option is	specified, then	under the -e option, diff3 publishes a
     script for	the editor ed(1) that will incorporate into file1 all changes
     between file2 and file3, i.e.  the	changes	that normally would be flagged
     ==== and ====3.  Option -x	(-3) produces a	script to incorporate only
     changes flagged ==== (====3).  The	following command will apply the
     resulting script to `file1', and emit the result on the output stream.

		(cat script; echo '1,$p') | ed - file1

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





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DIFF3(1)							      DIFF3(1)



     For example, suppose lines	7-8 are	changed	in both	file1 and file3.  The
     merged output of the command

			   "diff3 -m file1 file2 file3"
     contains:

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

     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.

     If	the option -i is specified along with one of the options -exEX3, then
     the resulting edit	script has the editor commands

	       w
	       q

     added at the end.	Then the following command will	update `file1' in
     place with	the changes.

		ed - file1 < script

SEE ALSO    [Toc]    [Back]

     diff(1), ed(1).

BUGS    [Toc]    [Back]

     If	merges are done	by generating explicit scripts to input	to the editor,
     rather than by using the -m option, the merge is limited by the
     capabilities of the editor	ed(1).	The editor cannot handle excessively
     long lines, binary	files (with nul	bytes) or files	without	a trailing
     newline.

DIAGNOSTICS    [Toc]    [Back]

     An	exit status of 0 means diff3 was successful, 1 means some overlaps
     were found, and 2 means trouble.


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