1.\" $OpenBSD: diff3.1,v 1.7 2007/05/31 19:20:09 jmc Exp $ 2.\" 3.\" Copyright (c) 1990, 1993, 1994 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)diff3.1 8.2 (Berkeley) 4/18/94 31.\" $FreeBSD$ 32.\" 33.Dd August 23, 2021 34.Dt DIFF3 1 35.Os 36.Sh NAME 37.Nm diff3 38.Nd 3-way differential file comparison 39.Sh SYNOPSIS 40.Nm diff3 41.Op Fl 3aEeiTXx 42.Op Fl Fl diff-program Ar program 43.Op Fl Fl strip-trailing-cr 44.Op Fl L | Fl Fl label Ar label1 45.Op Fl L | Fl Fl label Ar label2 46.Op Fl L | Fl Fl label Ar label3 47.Ar file1 file2 file3 48.Sh DESCRIPTION 49The 50.Nm 51utility compares the contents of three different versions of a file, 52.Ar file1 , 53.Ar file2 54and 55.Ar file3 , 56writing the result to the standard output. 57The options describe different methods of merging and 58purging 59the separate versions into a new file. 60.Nm 61is used by 62.Xr rcs 1 63to merge specific versions or create 64new versions. 65.Pp 66The options are as follows: 67.Bl -tag -width "-E, -X" 68.It Fl 3 , Fl Fl easy-only 69Produces an output script suitable for 70.Xr ed 1 71with changes 72specific only to 73.Ar file3 . 74.It Fl a , Fl Fl text 75Treat all files as ASCII. 76.It Fl E , Fl Fl show-overlap 77.It Fl X 78Similar to 79.Fl e 80and 81.Fl x , 82respectively, but treat overlapping changes (i.e., changes that would 83be noted with ==== in the normal listing) differently. 84The overlapping lines from both files will be inserted by the edit script, 85bracketed by "<<<<<<" and ">>>>>>" lines. 86.It Fl e , Fl Fl ed 87Produces output in a form suitable as an input script for the 88.Xr ed 1 89utility. 90The script may then be used to merge differences common between all 91three files and differences specific to 92.Ar file1 93and 94.Ar file3 . 95In other words, the 96.Fl e 97option ignores differences specific to 98.Ar file1 99and 100.Ar file2 , 101and those specific to 102.Ar file2 103and 104.Ar file3 . 105It is useful for backing out changes specific to 106.Ar file2 107only. 108.It Fl i 109Appends 'w' and 'q' 110.Xr ed 1 111commands. 112.It Fl L , Fl Fl label 113Defines labels to print instead of file names 114.Ar file1 , 115.Ar file2 116and 117.Ar file3 . 118.It Fl T, Fl Fl initial-tab 119In the normal listing, 120use a tab instead of two spaces 121at the beginning of each line. 122In modes that produce an 123.Xr ed 1 124script, this option changes nothing. 125.It Fl x, Fl Fl overlap-only 126Produces an output script suitable for 127.Xr ed 1 128with changes 129specific only to all three versions. 130.It Fl Fl diff-program Ar program 131Use 132.Ar program 133instead of the default 134.Xr diff 1 135to compare files. 136.It Fl Fl strip-trailing-cr 137Strip trailing carriage return on input files. 138.El 139.Pp 140The 141.Fl E 142option is used by 143.Tn RCS 144.Xr merge 1 145to ensure that overlapping changes in the merged files are preserved 146and brought to someone's attention. 147.Pp 148For example, suppose lines 7-8 are changed in both 149.Ar file1 150and 151.Ar file2 . 152Applying the edit script generated by the command 153.Pp 154.Dl $ diff3 -E file1 file2 file3 155.Pp 156to 157.Ar file1 158results in the file: 159.Bd -literal -offset indent 160lines 1-6 161of file1 162<<<<<<< file1 163lines 7-8 164of file1 165======= 166lines 7-8 167of file3 168>>>>>>> file3 169rest of file1 170.Ed 171.Pp 172The default output of 173.Nm 174makes notation of the differences between all files, and those 175differences specific to each pair of files. 176The changes are described by the commands necessary for 177.Xr ed 1 178to create the desired target from the different versions. 179See 180.Xr diff 1 181for a description of the commands. 182.Bl -tag -width "=====" 183.It Li \&==== 184The lines beneath this notation are ranges of lines which are different 185between all files. 186.It \&==== Ns Va n 187The lines beneath this notation are ranges of lines which are exclusively 188different in file 189.Va n . 190.El 191.Sh SEE ALSO 192.Xr diff 1 , 193.Xr ed 1 , 194.Xr merge 1 , 195.Xr rcs 1 , 196.Xr sdiff 1 197.Sh HISTORY 198A 199.Nm 200command appeared in 201.At v7 . 202.Sh BUGS 203The 204.Fl e 205option cannot catch and change lines which have 206.Ql \&. 207as the first and only character on the line. 208The resulting script will fail on that line 209as 210.Ql \&. 211is an 212.Xr ed 1 213editing command. 214