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1.1 root 1: .TH DIFF 1
2: .CT 1 files
3: .SH NAME
4: diff, diff3 \- differential file comparison
5: .SH SYNOPSIS
6: .B diff
7: [
8: .I option ...
9: ]
10: .I file1 file2
11: .PP
12: .B diff3
13: [
14: .B \-ex3
15: ]
16: .I file1 file2 file3
17: .SH DESCRIPTION
18: When run on regular files
19: .I diff
20: tells what lines must be changed in the files to bring them into agreement.
21: Except in rare circumstances,
22: .I diff
23: finds a smallest sufficient set of differences.
24: If neither file
25: is a directory, then one
26: may be
27: .LR - ,
28: meaning the standard input.
29: If one file
30: is a directory,
31: then a file in that directory with basename the same as that of
32: the other file is used.
33: .PP
34: If both files are directories,
35: similarly named files in the two directories
36: are compared by the method of
37: .I diff
38: for text files and
39: .IR cmp (1)
40: otherwise.
41: Options when comparing directories are:
42: .TP
43: .B -r
44: Apply
45: .I diff
46: recursively to similarly named subdirectories.
47: .TP
48: .B -s
49: Report files that are the same (normally not mentioned).
50: .PP
51: There are several options for output format;
52: the default output format contains lines of these forms:
53: .IP
54: .IB n1 a
55: .IB n3 , n4
56: .br
57: .IB n1 , n2 d
58: .I n3
59: .br
60: .IB n1 , n2 c
61: .IB n3 , n4
62: .PP
63: These lines resemble
64: .I ed
65: commands to convert
66: .I file1
67: into
68: .IR file2 .
69: The numbers after the letters pertain to
70: .IR file2 .
71: In fact, by exchanging
72: .L a
73: for
74: .L d
75: and reading backward
76: one may ascertain equally how to convert
77: .I file2
78: into
79: .IR file1 .
80: As in
81: .I ed,
82: identical pairs where
83: .IR n1 = n2
84: or
85: .I n3 = n4
86: are abbreviated as a single number.
87: .PP
88: Following each of these lines come all the lines that are
89: affected in the first file flagged by
90: .LR < ,
91: then all the lines that are affected in the second file
92: flagged by
93: .LR > .
94: .PP
95: Except for
96: .B -b,
97: which may be given with any of the others,
98: the following options are mutually exclusive:
99: .TP
100: .B -e
101: Produce a script of
102: .LR a ,
103: .LR c ,
104: and
105: .L d
106: for
107: .IR ed (1)
108: to recreate
109: .I file2
110: from
111: .IR file1 .
112: When comparing directories, produce a
113: .IR sh (1)
114: script to convert text files common to the two directories.
115: .TP
116: .BI -c n
117: Include
118: .I n
119: extra lines of context with each set of differences.
120: The output format is modified:
121: the output begins with identification of the files involved and
122: their creation dates and changes are separated
123: by lines of *'s.
124: Lines removed from
125: .I file1
126: are marked with
127: .LR - ;
128: those added to
129: .I file2
130: are marked
131: .LR + .
132: Lines which are changed from one
133: file to the other are marked in both files with
134: .LR ! .
135: .TP
136: .B -h
137: Do a fast, half-hearted job,
138: useful only when changed stretches are short
139: and well separated,
140: but does work on files of unlimited length.
141: .TP
142: .B -b
143: Ignore trailing blanks (spaces and tabs) and treat other
144: strings of blanks as if they were a single space.
145: .PP
146: .I Diff3
147: compares three versions of a file
148: and publishes the various disagreeing ranges of text.
149: One of the following indicators introduces each reported
150: difference.
151: .TP
152: .B ====
153: All three files differ.
154: .TP
155: .BI ==== f
156: File
157: .I f
158: differs, where
159: .I f
160: is 1, 2, or 3.
161: .PP
162: Disagreeing fragments from the three files follow the
163: .B ====
164: line, each identified by a
165: .IR diff -like
166: range indication:
167: .TP
168: .IB f : n1 a
169: File
170: .I f
171: lacks text that other files have; their text would
172: be appended after line
173: .I n1.
174: .TP
175: .IB f : n1 , n2 c
176: .br
177: .ns
178: .TP
179: .IB f : n1 c
180: Lines
181: .I n1
182: through
183: .I n2
184: (or line
185: .I n1
186: only) of file
187: .I f
188: would have to be changed to agree with some other file.
189: The original contents follow, unless a higher-numbered file
190: has the same contents.
191: .PP
192: Under option
193: .BR -e ,
194: .I diff3
195: publishes a script for
196: .IR ed (1)
197: that will incorporate into
198: .I file1
199: all changes between
200: .I file2
201: and
202: .I file3,
203: i.e. the changes that normally would be flagged
204: .B ====
205: and
206: .BR ====3 .
207: Option
208: .B \-x
209: (\fB\-3\fR)
210: produces a script to incorporate
211: only changes flagged
212: .B ====
213: .RB ( ====3 ).
214: .SH EXAMPLES
215: .TP
216: .L
217: (cat diff0-1 diff1-2 diff2-3; echo '1,$p') | ed - file0 >file3
218: An ancestral
219: .L file0
220: has been kept along with a chain of version-to-version
221: difference files made thus:
222: .LR "diff -e file0 file1 >diff0-1" .
223: The shell command reconstructs the latest version.
224: .PP
225: .EX
226: if diff3 mod1 old mod2 | grep -s '^====$'
227: then :
228: else (diff3 -e mod1 old mod2; echo '1,$p') | ed - mod1 >new
229: fi
230: .EE
231: .PD0
232: .IP
233: Compare two different modified versions with an old file.
234: If no modifications interfere with each other
235: .RI ( grep
236: finds no
237: .B ====
238: lines), make a new file incorporating both modifications.
239: .PD
240: .SH FILES
241: .F /tmp/d*
242: .br
243: .F /usr/lib/diffh
244: for
245: .B -h
246: .br
247: .F /usr/lib/diff3
248: .SH "SEE ALSO"
249: .IR cmp (1),
250: .IR comm (1),
251: .IR ed (1),
252: .IR idiff (1)
253: .SH DIAGNOSTICS
254: .I Diff
255: yields exit status is 0 for no differences, 1 for some, 2 for trouble.
256: .SH BUGS
257: Text lines that consist of a single `.' will
258: defeat options
259: .BR -e ,
260: .BR -x ,
261: and
262: .BR -3 .
263: .br
264: Superfluous output may result for files that differ
265: only in insignificant blanks when comparing directories
266: under option
267: .BR -b .
268: .br
269: Option
270: .B -c
271: is superfluous.
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