.\"
.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	from 4.3BSD diff.1	6.4 (Berkeley) 5/19/86
.\"
.\" This code contains changes by
.\" Gunnar Ritter, Freiburg i. Br., Germany, March 2003. All rights reserved.
.\"
.\" Conditions 1, 2, and 4 and the no-warranty notice below apply
.\" to these changes.
.\"
.\"
.\" Copyright (c) 1980, 1993
.\" 	The Regents of the University of California.  All rights reserved.
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowedgement:
.\" 	This product includes software developed by the University of
.\" 	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\"    above copyright notice, this list of conditions and the following
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.\"   Redistributions in binary form must reproduce the above copyright
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.\"    documentation and/or other materials provided with the distribution.
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.\"    must display the following acknowledgement:
.\"      This product includes software developed or owned by Caldera
.\"      International, Inc.
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.\"    derived from this software without specific prior written permission.
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.\" USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
.\" INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE
.\" LIABLE FOR ANY DIRECT, INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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.\"
.TH DIFF 1 "6/28/05" "Heirloom Toolchest" "User Commands"
.SH NAME
diff \- differential file comparator
.SH SYNOPSIS
.HP
.nh
.ad l
\fBdiff\fR
[\fB\-abBiptw\fR]
[\fB\-cefhnu\fR]
[\fB\-C\ \fInumber\fR]
[\fB\-U\ \fInumber\fR]
\fIfile1\fR \fIfile2\fR
.HP
.nh
.ad l
\fBdiff\fR
[\fB\-abBiptw\fR]
[\fB\-D\ \fIstring\fR]
\fIfile1\fR \fIfile2\fR
.HP
.nh
.ad l
\fBdiff\fR
[\fB\-abBiNptw12\fR]
[\fB\-cefhnu\fR]
[\fB\-C\ \fInumber\fR]
[\fB\-U\ \fInumber\fR]
[\fB\-lrs\fR]
[\fB\-S\ \fIname\fR]
[\fB\-x\ \fIpattern\fR]
[\fB\-X\ \fIname\fR]
\fIdirectory1\fR \fIdirectory2\fR
.br
.hy 1
.SH DESCRIPTION
.I Diff
tells what lines must be changed in two files to bring them
into agreement.
If
.I file1
.RI ( file2 )
is `\-', the standard input is used.
If
.I file1
.RI ( file2 )
is a directory, then a file in that directory
whose file-name is the same as the file-name of
.I file2
.RI ( file1 )
is used.
The normal output contains lines of these forms:
.IP "" 5
.I n1
a
.I n3,n4
.br
.I n1,n2
d
.I n3
.br
.I n1,n2
c
.I n3,n4
.PP
These lines resemble
.I ed
commands to convert
.I file1
into
.IR file2 .
The numbers after the letters pertain to
.IR file2 .
In fact, by exchanging `a' for `d' and reading backward
one may ascertain equally how to convert 
.I file2
into
.IR file1 .
As in 
.I ed,
identical pairs where
.I n1
=
.I n2
or
.I n3
=
.I n4
are abbreviated as a single number.
.PP
Following each of these lines come all the lines that are
affected in the first file flagged by `<', 
then all the lines that are affected in the second file
flagged by `>'.
.TP 10
.B \-a
causes a list of differences to be output
for all files,
even for those found to have binary content.
This option is an extension.
.TP 10
.B \-b
causes trailing whitespace characters
to be ignored, and other
strings of whitespace to compare equal.
.TP 10
.B \-i
ignores the case of letters.  E.g., ``A'' will compare equal to ``a''.
.TP 10
.B \-p
causes the name of the surrounding C function,
or, more exactly,
of the first previous unchanged line
beginning with a letter, the dollar sign, or the underscore,
to be output with each set of changes.
Implies
.I \-c
unless
.I \-u
is also present.
This option is an extension.
.TP 10
.B \-t
will expand tabs in output lines.  Normal,
.B \-c
or
.B \-u
output adds character(s) to the front of each line which may screw up
the indentation of the original source lines and make the output listing
difficult to interpret.  This option will preserve the original source's
indentation.
.TP 10
.B \-w
is similar to
.B \-b
but causes whitespace characters
to be totally ignored.
E.g., ``if\ (\ a\ ==\ b\ )'' will compare equal to ``if(a==b)''.
.TP 10
.B \-B
causes changes that consist entirely of empty lines added or deleted
to be ignored.
This option is an extension.
.PP
The following options are mutually exclusive:
.TP 10
.B \-c
produces a diff with three lines of context.
With
.B \-c
the output format is modified slightly:
the output beginning with identification of the files involved and
their creation dates and then each change is separated
by a line with a dozen *'s.
The lines removed from
.I file1
are marked with `\(mi '; those added to
.I file2
are marked `+ '.  Lines which are changed from one
file to the other are marked in both files with with `! '.
.\".sp
.\"Changes which lie within <context> lines of each other are grouped
.\"together on output.  (This is a change from the previous ``diff -c''
.\"but the resulting output is usually much easier to interpret.)
.TP 10
\fB\-C\ \fInumber\fR
Same as
.B \-c
but uses
.I number
of lines of context.
.TP 10
\fB\-D\ \fIstring\fR
causes
.I diff
to create a merged version of
.I file1
and
.I file2
on the standard output, with C preprocessor controls included so that
a compilation of the result without defining \fIstring\fR is equivalent
to compiling
.I file1,
while defining
.I string
will yield
.I file2.
.TP 10
.B \-e
produces a script of
.I "a, c"
and 
.I d
commands for the editor
.I ed,
which will recreate
.I file2
from
.IR file1 .
In connection with
.BR \-e ,
the following shell program may help maintain
multiple versions of a file.
Only an ancestral file ($1) and a chain of 
version-to-version
.I ed
scripts ($2,$3,...) made by
.I diff
need be on hand.
A `latest version' appears on
the standard output.
.IP
\ \ \ \ \ \ \ \ (shift; cat $*; echo \'1,$p\') \(bv ed \- $1
.IP
Extra commands are added to the output when comparing directories with
.B \-e,
so that the result is a
.IR sh (1)
script for converting text files which are common to the two directories
from their state in
.I dir1
to their state in
.I dir2.
.TP 10
.B \-f
produces a script similar to that of
.B \-e,
not useful with
.I ed,
and in the opposite order.
.TP 10
.B \-h
does a fast, half-hearted job.
It works only when changed stretches are short
and well separated,
but does work on files of unlimited length.
.TP 10
.B \-n
produces a script similar to that of
.B \-e,
but in the opposite order and with a count of changed lines on each
insert or delete command.
.\"This is the form used by
.\".IR rcsdiff (1).
.TP 10
.B \-u
produces a unified diff with three lines of context.
The output begins with identification of the files involved
and their creation dates,
followed by the changes
separated by `@@ \-range +range @@'.
Lines removed from
.I file1
are marked with `\(mi',
those added to
.I file2
are marked `+'.
This option is an extension.
.TP 10
\fB\-U\ \fInumber\fR
Same as
.B \-u
but uses
.I number
of lines of context.
This option is an extension.
.PP
If both arguments are directories,
.I diff
sorts the contents of the directories by name, and then runs the
regular file
.I diff
algorithm on text files which are different.
Binary files which differ,
common subdirectories, and files which appear in only one directory
are listed.
.PP
Options when comparing directories are:
.TP 10
.B \-l
long output format; each text file
.I diff
is piped through
.IR pr (1)
to paginate it,
other differences are remembered and summarized
after all text file differences are reported.
.TP 10
.B \-N
causes the text of files
that exist in one directory only
to be output
as if compared to an empty file modified at 1/1/70.
This option is an extension.
.TP 10
.B \-1
is similar to
.IR \-N ,
but causes just the text of files that exist in
.I directory1
only to be output.
Files that exist only in
.I directory2
are listed.
This option is an extension.
.TP 10
.B \-2
is similar to
.IR \-N ,
but causes just the text of files that exist in
.I directory2
only to be output.
Files that exist only in
.I directory1
are listed.
This option is an extension.
.TP 10
.B \-r
causes application of
.I diff
recursively to common subdirectories encountered.
.TP 10
.B \-s
causes 
.I diff
to report files which are the same, which are otherwise not mentioned.
.TP 10
.BI \-S " name"
starts a directory
.I diff
in the middle beginning with file
.I name.
.TP 10
.BI \-x " pattern"
excludes all file names that match
.I pattern
(as described in
.IR glob (7))
from comparison.
If
.I pattern
matches a directory,
files below that directory are also excluded.
This option is an extension.
.TP 10
.BI \-X " name"
excludes all file names contained in
.IR name .
This option is an extension.
.SH "ENVIRONMENT VARIABLES"
.TP
.BR LANG ", " LC_ALL
See
.IR locale(7).
.TP
.B LC_CTYPE
Sets the mapping of bytes to characters,
character case translation
and the set of whitespace characters.
.TP
.B SYSV3
If this variable is set,
invalid options are ignored instead of being rejected,
and the text of some diagnostic messages is changed.
.SH FILES
.ta \w'/usr/5lib/diffh   'u
/tmp/d?????
.br
/usr/5lib/diffh	for \fB\-h\fR
.br
diff	for directory diffs
.br
pr
.SH "SEE ALSO"
bdiff(1),
cmp(1),
cc(1),
comm(1),
ed(1),
diff3(1),
patch(1),
locale(7)
.SH DIAGNOSTICS
Exit status is 0 for no differences, 1 for some, 2 for trouble.
.SH NOTES
Editing scripts produced under the
.BR \-e " or"
.BR \-f " option are naive about"
creating lines consisting of a single `\fB.\fR'.
.PP
When comparing directories with the
\fB\-b, \-w\fP, or \fB\-i\fP
options specified,
.I diff
first compares the files ala
.I cmp,
and then decides to run the
.I diff
algorithm if they are not equal.
This may cause a small amount of spurious output if the files
then turn out to be identical because the only differences are
insignificant blank string or case differences.
.PP
When
.I diff
output is used with
.IR ed (1)
or
.IR patch (1)
for file synchronization,
it is recommended that it is run in the
.I C
or another single-byte LC_CTYPE locale
since character-to-byte conversion
might otherwise hide some changes.