Commit | Line | Data |
---|---|---|
416253bc C |
1 | .TH DIFF 1 "18 January 1983" |
2 | .UC 4 | |
3 | .SH NAME | |
4 | diff \- differential file and directory comparator | |
5 | .SH SYNOPSIS | |
6 | .B diff | |
7 | [ | |
8 | .B \-l | |
9 | ] [ | |
10 | .B \-r | |
11 | ] [ | |
12 | .B \-s | |
13 | ] [ | |
14 | \fB\-cefh\fR | |
15 | ] [ | |
16 | .B \-b | |
17 | ] dir1 dir2 | |
18 | .br | |
19 | .B diff | |
20 | [ | |
21 | \fB\-cefh | |
22 | ] [ | |
23 | \fB\-b\fR | |
24 | ] file1 file2 | |
25 | .br | |
26 | .B diff | |
27 | [ | |
28 | .BI \-D string | |
29 | ] [ | |
30 | .B \-b | |
31 | ] | |
32 | file1 file2 | |
33 | .SH DESCRIPTION | |
34 | If both arguments are directories, | |
35 | .I diff | |
36 | sorts the contents of the directories by name, and then runs the | |
37 | regular file | |
38 | .I diff | |
39 | algorithm (described below) | |
40 | on text files which are different. | |
41 | Binary files which differ, | |
42 | common subdirectories, and files which appear in only one directory | |
43 | are listed. | |
44 | Options when comparing directories are: | |
45 | .TP | |
46 | .B \-l | |
47 | long output format; each text file | |
48 | .I diff | |
49 | is piped through | |
50 | .IR pr (1) | |
51 | to paginate it, | |
52 | other differences are remembered and summarized | |
53 | after all text file differences are reported. | |
54 | .TP | |
55 | .B \-r | |
56 | causes application of | |
57 | .I diff | |
58 | recursively to common subdirectories encountered. | |
59 | .TP | |
60 | .B \-s | |
61 | causes | |
62 | .I diff | |
63 | to report files which are the same, which are otherwise not mentioned. | |
64 | .TP | |
65 | .B \-Sname | |
66 | starts a directory | |
67 | .I diff | |
68 | in the middle beginning with file | |
69 | .I name. | |
70 | .PP | |
71 | When run on regular files, and when comparing text files which differ | |
72 | during directory comparison, | |
73 | .I diff | |
74 | tells what lines must be changed in the files to bring them into agreement. | |
75 | Except in rare circumstances, | |
76 | .I diff | |
77 | finds a smallest sufficient set of file differences. | |
78 | If neither | |
79 | .I file1 | |
80 | nor | |
81 | .I file2 | |
82 | is a directory, then either | |
83 | may be given as `\-', in which case the standard input is used. | |
84 | If | |
85 | .I file1 | |
86 | is a directory, | |
87 | then a file in that directory whose file-name is the same as the file-name of | |
88 | .I file2 | |
89 | is used (and vice versa). | |
90 | .PP | |
91 | There are several options for output format; | |
92 | the default output format contains lines of these forms: | |
93 | .IP "" 5 | |
94 | .I n1 | |
95 | a | |
96 | .I n3,n4 | |
97 | .br | |
98 | .I n1,n2 | |
99 | d | |
100 | .I n3 | |
101 | .br | |
102 | .I n1,n2 | |
103 | c | |
104 | .I n3,n4 | |
105 | .PP | |
106 | These lines resemble | |
107 | .I ed | |
108 | commands to convert | |
109 | .I file1 | |
110 | into | |
111 | .IR file2 . | |
112 | The numbers after the letters pertain to | |
113 | .IR file2 . | |
114 | In fact, by exchanging `a' for `d' and reading backward | |
115 | one may ascertain equally how to convert | |
116 | .I file2 | |
117 | into | |
118 | .IR file1 . | |
119 | As in | |
120 | .I ed, | |
121 | identical pairs where | |
122 | .I n1 | |
123 | = | |
124 | .I n2 | |
125 | or | |
126 | .I n3 | |
127 | = | |
128 | .I n4 | |
129 | are abbreviated as a single number. | |
130 | .PP | |
131 | Following each of these lines come all the lines that are | |
132 | affected in the first file flagged by `<', | |
133 | then all the lines that are affected in the second file | |
134 | flagged by `>'. | |
135 | .PP | |
136 | Except for | |
137 | .B \-b, | |
138 | which may be given with any of the others, | |
139 | the following options are mutually exclusive: | |
140 | .TP 9 | |
141 | .B \-e | |
142 | producing a script of | |
143 | .I "a, c" | |
144 | and | |
145 | .I d | |
146 | commands for the editor | |
147 | .I ed, | |
148 | which will recreate | |
149 | .I file2 | |
150 | from | |
151 | .IR file1 . | |
152 | In connection with | |
153 | .BR \-e , | |
154 | the following shell program may help maintain | |
155 | multiple versions of a file. | |
156 | Only an ancestral file ($1) and a chain of | |
157 | version-to-version | |
158 | .I ed | |
159 | scripts ($2,$3,...) made by | |
160 | .I diff | |
161 | need be on hand. | |
162 | A `latest version' appears on | |
163 | the standard output. | |
164 | .IP | |
165 | \ \ \ \ \ \ \ \ (shift; cat $*; echo \'1,$p\') \(bv ed \- $1 | |
166 | .IP | |
167 | Extra commands are added to the output when comparing directories with | |
168 | .B \-e, | |
169 | so that the result is a | |
170 | .IR sh (1) | |
171 | script for converting text files which are common to the two directories | |
172 | from their state in | |
173 | .I dir1 | |
174 | to their state in | |
175 | .I dir2. | |
176 | .TP 9 | |
177 | .B \-f | |
178 | produces a script similar to that of | |
179 | .B \-e, | |
180 | not useful with | |
181 | .I ed, | |
182 | and in the opposite order. | |
183 | .TP 9 | |
184 | .B \-c | |
185 | produces a diff with lines of context. | |
186 | The default is to present 3 lines of context and may be changed, e.g to 10, by | |
187 | .BR \-c10 \&. | |
188 | With | |
189 | .B \-c | |
190 | the output format is modified slightly: | |
191 | the output beginning with identification of the files involved and | |
192 | their creation dates and then each change is separated | |
193 | by a line with a dozen *'s. | |
194 | The lines removed from | |
195 | .I file1 | |
196 | are marked with `\(mi'; those added to | |
197 | .I file2 | |
198 | are marked `+'. Lines which are changed from one | |
199 | file to the other are marked in both files with `!'. | |
200 | .TP 9 | |
201 | .B \-h | |
202 | does a fast, half-hearted job. | |
203 | It works only when changed stretches are short | |
204 | and well separated, | |
205 | but does work on files of unlimited length. | |
206 | .TP | |
207 | .B \-Dstring | |
208 | causes | |
209 | .I diff | |
210 | to create a merged version of | |
211 | .I file1 | |
212 | and | |
213 | .I file2 | |
214 | on the standard output, with C preprocessor controls included so that | |
215 | a compilation of the result without defining \fIstring\fR is equivalent | |
216 | to compiling | |
217 | .I file1, | |
218 | while defining | |
219 | .I string | |
220 | will yield | |
221 | .I file2. | |
222 | .TP | |
223 | .B \-b | |
224 | causes trailing blanks (spaces and tabs) to be ignored, and other | |
225 | strings of blanks to compare equal. | |
226 | .SH FILES | |
227 | /tmp/d????? | |
228 | .br | |
229 | /usr/lib/diffh for | |
230 | .B \-h | |
231 | .br | |
232 | /bin/pr | |
233 | .SH "SEE ALSO" | |
234 | cmp(1), cc(1), comm(1), ed(1), diff3(1) | |
235 | .SH DIAGNOSTICS | |
236 | Exit status is 0 for no differences, 1 for some, 2 for trouble. | |
237 | .SH BUGS | |
238 | Editing scripts produced under the | |
239 | .BR \-e " or" | |
240 | .BR \-f " option are naive about" | |
241 | creating lines consisting of a single `\fB.\fR'. | |
242 | .PP | |
243 | When comparing directories with the | |
244 | .B \-b | |
245 | option specified, | |
246 | .I diff | |
247 | first compares the files ala | |
248 | .I cmp, | |
249 | and then decides to run the | |
250 | .I diff | |
251 | algorithm if they are not equal. | |
252 | This may cause a small amount of spurious output if the files | |
253 | then turn out to be identical because the only differences are | |
254 | insignificant blank string differences. |