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diff.1 (11347B)


      1 .\" $OpenBSD: diff.1,v 1.43 2014/02/13 14:52:53 jmc Exp $
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     30 .\"     @(#)diff.1	8.1 (Berkeley) 6/30/93
     31 .\"
     32 .Dd $Mdocdate: February 13 2014 $
     33 .Dt DIFF 1
     34 .Os
     35 .Sh NAME
     36 .Nm diff
     37 .Nd differential file and directory comparator
     38 .Sh SYNOPSIS
     39 .Nm diff
     40 .Op Fl abdilpTtw
     41 .Oo
     42 .Fl c | e | f |
     43 .Fl n | q | u
     44 .Oc
     45 .Op Fl I Ar pattern
     46 .Op Fl L Ar label
     47 .Ar file1 file2
     48 .Nm diff
     49 .Op Fl abdilpTtw
     50 .Op Fl I Ar pattern
     51 .Op Fl L Ar label
     52 .Fl C Ar number
     53 .Ar file1 file2
     54 .Nm diff
     55 .Op Fl abdiltw
     56 .Op Fl I Ar pattern
     57 .Fl D Ar string
     58 .Ar file1 file2
     59 .Nm diff
     60 .Op Fl abdilpTtw
     61 .Op Fl I Ar pattern
     62 .Op Fl L Ar label
     63 .Fl U Ar number
     64 .Ar file1 file2
     65 .Nm diff
     66 .Op Fl abdilNPprsTtw
     67 .Oo
     68 .Fl c | e | f |
     69 .Fl n | q | u
     70 .Oc
     71 .Op Fl I Ar pattern
     72 .Bk -words
     73 .Op Fl L Ar label
     74 .Op Fl S Ar name
     75 .Op Fl X Ar file
     76 .Op Fl x Ar pattern
     77 .Ek
     78 .Ar dir1 dir2
     79 .Sh DESCRIPTION
     80 The
     81 .Nm
     82 utility compares the contents of
     83 .Ar file1
     84 and
     85 .Ar file2
     86 and writes to the standard output the list of changes necessary to
     87 convert one file into the other.
     88 No output is produced if the files are identical.
     89 .Pp
     90 Output options (mutually exclusive):
     91 .Bl -tag -width Ds
     92 .It Fl C Ar number
     93 Like
     94 .Fl c
     95 but produces a diff with
     96 .Ar number
     97 lines of context.
     98 .It Fl c
     99 Produces a diff with 3 lines of context.
    100 With
    101 .Fl c
    102 the output format is modified slightly:
    103 the output begins with identification of the files involved and
    104 their creation dates and then each change is separated
    105 by a line with fifteen
    106 .Li * Ns 's .
    107 The lines removed from
    108 .Ar file1
    109 are marked with
    110 .Sq \&-\ \& ;
    111 those added to
    112 .Ar file2
    113 are marked
    114 .Sq \+\ \& .
    115 Lines which are changed from one file to the other are marked in
    116 both files with
    117 .Sq !\ \& .
    118 Changes which lie within 3 lines of each other are grouped together on
    119 output.
    120 .It Fl D Ar string
    121 Creates a merged version of
    122 .Ar file1
    123 and
    124 .Ar file2
    125 on the standard output, with C preprocessor controls included so that
    126 a compilation of the result without defining
    127 .Ar string
    128 is equivalent to compiling
    129 .Ar file1 ,
    130 while defining
    131 .Ar string
    132 will yield
    133 .Ar file2 .
    134 .It Fl e
    135 Produces output in a form suitable as input for the editor utility,
    136 .Xr ed 1 ,
    137 which can then be used to convert file1 into file2.
    138 .Pp
    139 Extra commands are added to the output when comparing directories with
    140 .Fl e ,
    141 so that the result is a
    142 .Xr sh 1
    143 script for converting text files which are common to the two directories
    144 from their state in
    145 .Ar dir1
    146 to their state in
    147 .Ar dir2 .
    148 .It Fl f
    149 Identical output to that of the
    150 .Fl e
    151 flag, but in reverse order.
    152 It cannot be digested by
    153 .Xr ed 1 .
    154 .It Fl n
    155 Produces a script similar to that of
    156 .Fl e ,
    157 but in the opposite order and with a count of changed lines on each
    158 insert or delete command.
    159 This is the form used by
    160 .Xr rcsdiff 1 .
    161 .It Fl q
    162 Just print a line when the files differ.
    163 Does not output a list of changes.
    164 .It Fl U Ar number
    165 Like
    166 .Fl u
    167 but produces a diff with
    168 .Ar number
    169 lines of context.
    170 .It Fl u
    171 Produces a
    172 .Em unified
    173 diff with 3 lines of context.
    174 A unified diff is similar to the context diff produced by the
    175 .Fl c
    176 option.
    177 However, unlike with
    178 .Fl c ,
    179 all lines to be changed (added and/or removed) are present in
    180 a single section.
    181 .El
    182 .Pp
    183 Comparison options:
    184 .Bl -tag -width Ds
    185 .It Fl a
    186 Treat all files as
    187 .Tn ASCII
    188 text.
    189 Normally
    190 .Nm
    191 will simply print
    192 .Dq Binary files ... differ
    193 if files contain binary characters.
    194 Use of this option forces
    195 .Nm
    196 to produce a diff.
    197 .It Fl b
    198 Causes trailing blanks (spaces and tabs) to be ignored, and other
    199 strings of blanks to compare equal.
    200 .It Fl d
    201 Try very hard to produce a diff as small as possible.
    202 This may consume a lot of processing power and memory when processing
    203 large files with many changes.
    204 .It Fl I Ar pattern
    205 Ignores changes, insertions, and deletions whose lines match the
    206 extended regular expression
    207 .Ar pattern .
    208 Multiple
    209 .Fl I
    210 patterns may be specified.
    211 All lines in the change must match some pattern for the change to be
    212 ignored.
    213 See
    214 .Xr re_format 7
    215 for more information on regular expression patterns.
    216 .It Fl i
    217 Ignores the case of letters.
    218 E.g.,
    219 .Dq A
    220 will compare equal to
    221 .Dq a .
    222 .It Fl L Ar label
    223 Print
    224 .Ar label
    225 instead of the first (and second, if this option is specified twice)
    226 file name and time in the context or unified diff header.
    227 .It Fl l
    228 Long output format; each text file
    229 .Nm diff Ns \'d
    230 is piped through
    231 .Xr pr 1
    232 to paginate it;
    233 other differences are remembered and summarized
    234 after all text file differences are reported.
    235 .It Fl p
    236 With unified and context diffs, show with each change
    237 the first 40 characters of the last line before the context beginning
    238 with a letter, an underscore or a dollar sign.
    239 For C source code following standard layout conventions, this will
    240 show the prototype of the function the change applies to.
    241 .It Fl T
    242 Print a tab rather than a space before the rest of the line for the
    243 normal, context or unified output formats.
    244 This makes the alignment of tabs in the line consistent.
    245 .It Fl t
    246 Will expand tabs in output lines.
    247 Normal or
    248 .Fl c
    249 output adds character(s) to the front of each line which may screw up
    250 the indentation of the original source lines and make the output listing
    251 difficult to interpret.
    252 This option will preserve the original source's indentation.
    253 .It Fl w
    254 Is similar to
    255 .Fl b
    256 but causes whitespace (blanks and tabs) to be totally ignored.
    257 E.g.,
    258 .Dq if (\ \&a == b \&)
    259 will compare equal to
    260 .Dq if(a==b) .
    261 .El
    262 .Pp
    263 Directory comparison options:
    264 .Bl -tag -width Ds
    265 .It Fl N
    266 If a file is found in only one directory, act as if it was found in the
    267 other directory too but was of zero size.
    268 .It Fl P
    269 If a file is found only in
    270 .Ar dir2 ,
    271 act as if it was found in
    272 .Ar dir1
    273 too but was of zero size.
    274 .It Fl r
    275 Causes application of
    276 .Nm
    277 recursively to common subdirectories encountered.
    278 .It Fl S Ar name
    279 Re-starts a directory
    280 .Nm
    281 in the middle, beginning with file
    282 .Ar name .
    283 .It Fl s
    284 Causes
    285 .Nm
    286 to report files which are the same, which are otherwise not mentioned.
    287 .It Fl X Ar file
    288 Exclude files and subdirectories from comparison whose basenames match
    289 lines in
    290 .Ar file .
    291 Multiple
    292 .Fl X
    293 options may be specified.
    294 .It Fl x Ar pattern
    295 Exclude files and subdirectories from comparison whose basenames match
    296 .Ar pattern .
    297 Patterns are matched using shell-style globbing via
    298 .Xr fnmatch 3 .
    299 Multiple
    300 .Fl x
    301 options may be specified.
    302 .El
    303 .Pp
    304 If both arguments are directories,
    305 .Nm
    306 sorts the contents of the directories by name, and then runs the
    307 regular file
    308 .Nm
    309 algorithm, producing a change list,
    310 on text files which are different.
    311 Binary files which differ,
    312 common subdirectories, and files which appear in only one directory
    313 are described as such.
    314 In directory mode only regular files and directories are compared.
    315 If a non-regular file such as a device special file or
    316 .Tn FIFO
    317 is encountered, a diagnostic message is printed.
    318 .Pp
    319 If only one of
    320 .Ar file1
    321 and
    322 .Ar file2
    323 is a directory,
    324 .Nm
    325 is applied to the non-directory file and the file contained in
    326 the directory file with a filename that is the same as the
    327 last component of the non-directory file.
    328 .Pp
    329 If either
    330 .Ar file1
    331 or
    332 .Ar file2
    333 is
    334 .Sq - ,
    335 the standard input is
    336 used in its place.
    337 .Ss Output Style
    338 The default (without
    339 .Fl e ,
    340 .Fl c ,
    341 or
    342 .Fl n
    343 .\" -C
    344 options)
    345 output contains lines of these forms, where
    346 .Va XX , YY , ZZ , QQ
    347 are line numbers respective of file order.
    348 .Pp
    349 .Bl -tag -width "XX,YYcZZ,QQ" -compact
    350 .It Li XX Ns Ic a Ns Li YY
    351 At (the end of) line
    352 .Va XX
    353 of
    354 .Ar file1 ,
    355 append the contents
    356 of line
    357 .Va YY
    358 of
    359 .Ar file2
    360 to make them equal.
    361 .It Li XX Ns Ic a Ns Li YY,ZZ
    362 Same as above, but append the range of lines,
    363 .Va YY
    364 through
    365 .Va ZZ
    366 of
    367 .Ar file2
    368 to line
    369 .Va XX
    370 of file1.
    371 .It Li XX Ns Ic d Ns Li YY
    372 At line
    373 .Va XX
    374 delete
    375 the line.
    376 The value
    377 .Va YY
    378 tells to which line the change would bring
    379 .Ar file1
    380 in line with
    381 .Ar file1 .
    382 .It Li XX,YY Ns Ic d Ns Li ZZ
    383 Delete the range of lines
    384 .Va XX
    385 through
    386 .Va YY
    387 in
    388 .Ar file1 .
    389 .It Li XX Ns Ic c Ns Li YY
    390 Change the line
    391 .Va XX
    392 in
    393 .Ar file1
    394 to the line
    395 .Va YY
    396 in
    397 .Ar file2 .
    398 .It Li XX,YY Ns Ic c Ns Li ZZ
    399 Replace the range of specified lines with the line
    400 .Va ZZ .
    401 .It Li XX,YY Ns Ic c Ns Li ZZ,QQ
    402 Replace the range
    403 .Va XX , Ns Va YY
    404 from
    405 .Ar file1
    406 with the range
    407 .Va ZZ , Ns Va QQ
    408 from
    409 .Ar file2 .
    410 .El
    411 .Pp
    412 These lines resemble
    413 .Xr ed 1
    414 subcommands to convert
    415 .Ar file1
    416 into
    417 .Ar file2 .
    418 The line numbers before the action letters pertain to
    419 .Ar file1 ;
    420 those after pertain to
    421 .Ar file2 .
    422 Thus, by exchanging
    423 .Ic a
    424 for
    425 .Ic d
    426 and reading the line in reverse order, one can also
    427 determine how to convert
    428 .Ar file2
    429 into
    430 .Ar file1 .
    431 As in
    432 .Xr ed 1 ,
    433 identical
    434 pairs (where num1 = num2) are abbreviated as a single
    435 number.
    436 .Sh ENVIRONMENT
    437 .Bl -tag -width TMPDIR
    438 .It Ev TMPDIR
    439 If the environment variable
    440 .Ev TMPDIR
    441 exists,
    442 .Nm
    443 will use the directory specified by
    444 .Ev TMPDIR
    445 as the temporary directory.
    446 .El
    447 .Sh FILES
    448 .Bl -tag -width /tmp/diff.XXXXXXXX -compact
    449 .It Pa /tmp/diff. Ns Ar XXXXXXXX
    450 Temporary file used when comparing a device or the standard input.
    451 Note that the temporary file is unlinked as soon as it is created
    452 so it will not show up in a directory listing.
    453 .El
    454 .Sh EXIT STATUS
    455 The
    456 .Nm
    457 utility exits with one of the following values:
    458 .Pp
    459 .Bl -tag -width Ds -offset indent -compact
    460 .It 0
    461 No differences were found.
    462 .It 1
    463 Differences were found.
    464 .It >1
    465 An error occurred.
    466 .El
    467 .Sh SEE ALSO
    468 .Xr cmp 1 ,
    469 .Xr comm 1 ,
    470 .Xr diff3 1 ,
    471 .Xr ed 1 ,
    472 .Xr patch 1 ,
    473 .Xr sdiff 1
    474 .Rs
    475 .%A James W. Hunt
    476 .%A M. Douglas McIlroy
    477 .%T "An Algorithm for Differential File Comparison"
    478 .%J Computing Science Technical Report
    479 .%Q Bell Laboratories 41
    480 .%D June 1976
    481 .Re
    482 .Sh STANDARDS
    483 The
    484 .Nm
    485 utility is compliant with the
    486 .St -p1003.1-2008
    487 specification.
    488 .Pp
    489 The flags
    490 .Op Fl aDdIiLlNnPpqSsTtwXx ,
    491 as well as the
    492 .Ev TMPDIR
    493 environment variable,
    494 are extensions to that specification.
    495 .Sh HISTORY
    496 A
    497 .Nm
    498 command appeared in
    499 .At v6 .