506 lines
11 KiB
Groff
506 lines
11 KiB
Groff
.\" $OpenBSD: diff.1,v 1.37 2010/02/21 15:24:01 sobrado Exp $
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.\"
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.\" Copyright (c) 1980, 1990, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)diff.1 8.1 (Berkeley) 6/30/93
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.\"
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.Dd $Mdocdate: February 21 2010 $
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.Dt DIFF 1
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.Os
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.Sh NAME
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.Nm diff
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.Nd differential file and directory comparator
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.Sh SYNOPSIS
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.Nm diff
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.Op Fl abdilpTtw
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.Oo
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.Fl c | e | f |
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.Fl n | q | u
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.Oc
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.Op Fl I Ar pattern
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.Op Fl L Ar label
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.Ar file1 file2
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.Nm diff
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.Op Fl abdilpTtw
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.Op Fl I Ar pattern
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.Op Fl L Ar label
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.Fl C Ar number
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.Ar file1 file2
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.Nm diff
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.Op Fl abdiltw
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.Op Fl I Ar pattern
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.Fl D Ar string
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.Ar file1 file2
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.Nm diff
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.Op Fl abdilpTtw
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.Op Fl I Ar pattern
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.Op Fl L Ar label
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.Fl U Ar number
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.Ar file1 file2
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.Nm diff
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.Op Fl abdilNPprsTtw
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.Oo
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.Fl c | e | f |
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.Fl n | q | u
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.Oc
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.Op Fl I Ar pattern
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.Bk -words
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.Op Fl L Ar label
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.Op Fl S Ar name
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.Op Fl X Ar file
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.Op Fl x Ar pattern
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.Ek
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.Ar dir1 dir2
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.Sh DESCRIPTION
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The
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.Nm
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utility compares the contents of
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.Ar file1
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and
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.Ar file2
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and writes to the standard output the list of changes necessary to
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convert one file into the other.
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No output is produced if the files are identical.
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.Pp
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Output options (mutually exclusive):
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.Bl -tag -width Ds
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.It Fl C Ar number
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Like
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.Fl c
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but produces a diff with
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.Ar number
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lines of context.
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.It Fl c
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Produces a diff with 3 lines of context.
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With
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.Fl c
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the output format is modified slightly:
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the output begins with identification of the files involved and
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their creation dates and then each change is separated
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by a line with fifteen
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.Li * Ns 's .
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The lines removed from
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.Ar file1
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are marked with
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.Sq \&-\ \& ;
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those added to
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.Ar file2
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are marked
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.Sq \+\ \& .
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Lines which are changed from one file to the other are marked in
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both files with
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.Sq !\ \& .
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Changes which lie within 3 lines of each other are grouped together on
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output.
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.It Fl D Ar string
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Creates a merged version of
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.Ar file1
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and
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.Ar file2
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on the standard output, with C preprocessor controls included so that
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a compilation of the result without defining
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.Ar string
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is equivalent to compiling
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.Ar file1 ,
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while defining
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.Ar string
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will yield
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.Ar file2 .
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.It Fl e
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Produces output in a form suitable as input for the editor utility,
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.Xr ed 1 ,
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which can then be used to convert file1 into file2.
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.Pp
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Extra commands are added to the output when comparing directories with
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.Fl e ,
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so that the result is a
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.Xr sh 1
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script for converting text files which are common to the two directories
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from their state in
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.Ar dir1
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to their state in
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.Ar dir2 .
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.It Fl f
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Identical output to that of the
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.Fl e
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flag, but in reverse order.
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It cannot be digested by
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.Xr ed 1 .
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.It Fl n
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Produces a script similar to that of
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.Fl e ,
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but in the opposite order and with a count of changed lines on each
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insert or delete command.
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This is the form used by
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.Xr rcsdiff 1 .
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.It Fl q
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Just print a line when the files differ.
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Does not output a list of changes.
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.It Fl U Ar number
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Like
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.Fl u
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but produces a diff with
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.Ar number
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lines of context.
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.It Fl u
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Produces a
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.Em unified
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diff with 3 lines of context.
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A unified diff is similar to the context diff produced by the
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.Fl c
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option.
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However, unlike with
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.Fl c ,
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all lines to be changed (added and/or removed) are present in
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a single section.
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.El
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.Pp
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Comparison options:
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.Bl -tag -width Ds
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.It Fl a
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Treat all files as
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.Tn ASCII
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text.
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Normally
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.Nm
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will simply print
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.Dq Binary files ... differ
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if files contain binary characters.
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Use of this option forces
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.Nm
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to produce a diff.
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.It Fl b
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Causes trailing blanks (spaces and tabs) to be ignored, and other
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strings of blanks to compare equal.
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.It Fl d
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Try very hard to produce a diff as small as possible.
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This may consume a lot of processing power and memory when processing
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large files with many changes.
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.It Fl I Ar pattern
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Ignores changes, insertions, and deletions whose lines match the
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extended regular expression
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.Ar pattern .
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Multiple
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.Fl I
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patterns may be specified.
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All lines in the change must match some pattern for the change to be
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ignored.
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See
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.Xr re_format 7
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for more information on regular expression patterns.
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.It Fl i
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Ignores the case of letters.
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E.g.,
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.Dq A
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will compare equal to
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.Dq a .
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.It Fl L Ar label
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Print
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.Ar label
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instead of the first (and second, if this option is specified twice)
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file name and time in the context or unified diff header.
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.It Fl l
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Long output format; each text file
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.Nm diff Ns \'d
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is piped through
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.Xr pr 1
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to paginate it;
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other differences are remembered and summarized
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after all text file differences are reported.
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.It Fl p
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With unified and context diffs, show with each change
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the first 40 characters of the last line before the context beginning
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with a letter, an underscore or a dollar sign.
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For C source code following standard layout conventions, this will
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show the prototype of the function the change applies to.
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.It Fl T
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Print a tab rather than a space before the rest of the line for the
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normal, context or unified output formats.
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This makes the alignment of tabs in the line consistent.
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.It Fl t
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Will expand tabs in output lines.
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Normal or
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.Fl c
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output adds character(s) to the front of each line which may screw up
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the indentation of the original source lines and make the output listing
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difficult to interpret.
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This option will preserve the original source's indentation.
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.It Fl w
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Is similar to
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.Fl b
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but causes whitespace (blanks and tabs) to be totally ignored.
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E.g.,
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.Dq if (\ \&a == b \&)
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will compare equal to
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.Dq if(a==b) .
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.El
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.Pp
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Directory comparison options:
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.Bl -tag -width Ds
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.It Fl N
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If a file is found in only one directory, act as if it was found in the
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other directory too but was of zero size.
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.It Fl P
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If a file is found only in
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.Ar dir2 ,
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act as if it was found in
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.Ar dir1
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too but was of zero size.
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.It Fl r
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Causes application of
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.Nm
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recursively to common subdirectories encountered.
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.It Fl S Ar name
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Re-starts a directory
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.Nm
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in the middle, beginning with file
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.Ar name .
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.It Fl s
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Causes
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.Nm
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to report files which are the same, which are otherwise not mentioned.
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.It Fl X Ar file
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Exclude files and subdirectories from comparison whose basenames match
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lines in
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.Ar file .
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Multiple
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.Fl X
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options may be specified.
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.It Fl x Ar pattern
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Exclude files and subdirectories from comparison whose basenames match
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.Ar pattern .
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Patterns are matched using shell-style globbing via
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.Xr fnmatch 3 .
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Multiple
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.Fl x
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options may be specified.
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.El
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.Pp
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If both arguments are directories,
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.Nm
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sorts the contents of the directories by name, and then runs the
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regular file
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.Nm
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algorithm, producing a change list,
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on text files which are different.
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Binary files which differ,
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common subdirectories, and files which appear in only one directory
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are described as such.
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In directory mode only regular files and directories are compared.
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If a non-regular file such as a device special file or
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.Tn FIFO
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is encountered, a diagnostic message is printed.
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.Pp
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If only one of
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.Ar file1
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and
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.Ar file2
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is a directory,
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.Nm
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is applied to the non-directory file and the file contained in
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the directory file with a filename that is the same as the
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last component of the non-directory file.
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.Pp
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If either
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.Ar file1
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or
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.Ar file2
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is
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.Sq Fl ,
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the standard input is
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used in its place.
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.Ss Output Style
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The default (without
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.Fl e ,
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.Fl c ,
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or
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.Fl n
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.\" -C
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options)
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output contains lines of these forms, where
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.Va XX , YY , ZZ , QQ
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are line numbers respective of file order.
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.Pp
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.Bl -tag -width "XX,YYcZZ,QQ" -compact
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.It Li XX Ns Ic a Ns Li YY
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At (the end of) line
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.Va XX
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of
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.Ar file1 ,
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append the contents
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of line
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.Va YY
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of
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.Ar file2
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to make them equal.
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.It Li XX Ns Ic a Ns Li YY,ZZ
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Same as above, but append the range of lines,
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.Va YY
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through
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.Va ZZ
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of
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.Ar file2
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to line
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.Va XX
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of file1.
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.It Li XX Ns Ic d Ns Li YY
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At line
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.Va XX
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delete
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the line.
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The value
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.Va YY
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tells to which line the change would bring
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.Ar file1
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in line with
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.Ar file1 .
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.It Li XX,YY Ns Ic d Ns Li ZZ
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Delete the range of lines
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.Va XX
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through
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.Va YY
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in
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.Ar file1 .
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.It Li XX Ns Ic c Ns Li YY
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Change the line
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.Va XX
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in
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.Ar file1
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to the line
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.Va YY
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in
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.Ar file2 .
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.It Li XX,YY Ns Ic c Ns Li ZZ
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Replace the range of specified lines with the line
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.Va ZZ .
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.It Li XX,YY Ns Ic c Ns Li ZZ,QQ
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Replace the range
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.Va XX , Ns Va YY
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from
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.Ar file1
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with the range
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.Va ZZ , Ns Va QQ
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from
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.Ar file2 .
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.El
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.Pp
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These lines resemble
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.Xr ed 1
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subcommands to convert
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.Ar file1
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into
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.Ar file2 .
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The line numbers before the action letters pertain to
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.Ar file1 ;
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those after pertain to
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.Ar file2 .
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Thus, by exchanging
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.Ic a
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for
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.Ic d
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and reading the line in reverse order, one can also
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determine how to convert
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.Ar file2
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into
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.Ar file1 .
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As in
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.Xr ed 1 ,
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identical
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pairs (where num1 = num2) are abbreviated as a single
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number.
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.Sh ENVIRONMENT
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.Bl -tag -width TMPDIR
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.It Ev TMPDIR
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If the environment variable
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.Ev TMPDIR
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exists,
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.Nm
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will use the directory specified by
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.Ev TMPDIR
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as the temporary directory.
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.El
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.Sh FILES
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.Bl -tag -width /tmp/diff.XXXXXXXX -compact
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.It Pa /tmp/diff. Ns Ar XXXXXXXX
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Temporary file used when comparing a device or the standard input.
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Note that the temporary file is unlinked as soon as it is created
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so it will not show up in a directory listing.
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.El
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.Sh DIAGNOSTICS
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The
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.Nm
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utility exits with one of the following values:
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.Pp
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.Bl -tag -width Ds -compact -offset indent
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.It 0
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No differences were found.
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.It 1
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Differences were found.
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.It \*(Gt1
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An error occurred.
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.El
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.Sh SEE ALSO
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.Xr cmp 1 ,
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.Xr comm 1 ,
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.Xr diff3 1 ,
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.Xr ed 1 ,
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.Xr pr 1 ,
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.Xr sdiff 1 ,
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.Xr fnmatch 3 ,
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.Xr re_format 7
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.Sh STANDARDS
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The
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.Nm
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utility is compliant with the
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.St -p1003.1-2008
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specification.
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.Pp
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The flags
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.Op Fl aDdIiLlNnPpqSsTtwXx
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are extensions to that specification.
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.Sh HISTORY
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A
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.Nm
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command appeared in
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.At v6 .
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.Sh BUGS
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When comparing directories with the
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.Fl b ,
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.Fl w
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or
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.Fl i
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options specified,
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.Nm
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first compares the files ala
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.Xr cmp 1 ,
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and then decides to run the
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.Nm
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algorithm if they are not equal.
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This may cause a small amount of spurious output if the files
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then turn out to be identical because the only differences are
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insignificant whitespace or case differences.
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