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2012-02-19 16:16:08
DIFF(1) GNU Tools DIFF(1)
NAME
diff - find differences between two files
SYNOPSIS
diff [options] from-file to-file
DESCRIPTION
In the simplest case, diff compares the contents of the two files from-file and to-file. A file name of -
stands for text read from the standard input. As a special case, diff - - compares a copy of standard
input to itself.
在最简单应用中， diff比较两个文件from-file, to-file的差异。如果以"-"为文件名，则以标准输入为输入。 作为一个特例，diff -- 比较标准输入本身。
If from-file is a directory and to-file is not, diff compares the file in from-file whose file name is that
of to-file, and vice versa. The non-directory file must not be -.
如果"from-file"是一个路径名,而"to-file"不是路径名时，则diff比较的是"from-file"路径下和"to-file"相同名 的文件。反过来也是一样。这时，非路径文件不能是"-"。
If both from-file and to-file are directories, diff compares corresponding files in both directories, in
alphabetical order; this comparison is not recursive unless the -r or --recursive option is given. diff
never compares the actual contents of a directory as if it were a file. The file that is fully specified
may not be standard input, because standard input is nameless and the notion of ''file with the same name''
does not apply.
如果"from-file", "to-file"都是路径名，diff以字母顺序比较两个路径下相对就的文件。这个比较不会对目 录进行递进深入，除非指定了"-r "或"--recursive"选项。
diff options begin with -, so normally from-file and to-file may not begin with -. However, -- as an argu-
ment by itself treats the remaining arguments as file names even if they begin with -.
Options
Below is a summary of all of the options that GNU diff accepts. Most options have two equivalent names,
one of which is a single letter preceded by -, and the other of which is a long name preceded by --. Mul-
tiple single letter options (unless they take an argument) can be combined into a single command line word:
-ac is equivalent to -a -c. Long named options can be abbreviated to any unique prefix of their name.
Brackets ([ and ]) indicate that an option takes an optional argument.
-lines Show lines (an integer) lines of context. This option does not specify an output format by itself;
it has no effect unless it is combined with -c or -u. This option is obsolete. For proper opera-
tion, patch typically needs at least two lines of context.
-a Treat all files as text and compare them line-by-line, even if they do not seem to be text.
以文本方式逐行比较所有文件，即使它们不是文本文件。
-b Ignore changes in amount of white space.
忽略空格。
-B Ignore changes that just insert or delete blank lines.
忽略空行。
-q
--brief
Report only whether the files differ, not the details of the differences.
仅报告文件是否有差异，不进行细节的比较
-c Use the context output format.
使用上下文输出格式
-C lines
--context[=lines]
Use the context output format, showing lines (an integer) lines of context, or three if lines is not
given. For proper operation, patch typically needs at least two lines of context.
在使用上下文输出格式时，显示上下文的行数。Patch通常需要至少两行上下文行
--changed-group-format=format
Use format to output a line group containing differing lines from both files in if-then-else format.
-d Change the algorithm to perhaps find a smaller set of changes. This makes diff slower (sometimes
much slower).
-D name
Make merged if-then-else format output, conditional on the preprocessor macro name.
-e
--ed Make output that is a valid ed script.
--exclude=pattern
When comparing directories, ignore files and subdirectories whose basenames match pattern.
当比较文件路径时，忽略和"pattern"匹配的基本名的文件或子路径
--exclude-from=file
When comparing directories, ignore files and subdirectories whose basenames match any pattern contained in file.
当比较文件路径时，忽略文件"file"中指定的和基本名相匹配的任何文件名或子路径。
--expand-tabs
Expand tabs to spaces in the output, to preserve the alignment of tabs in the input files.
将tabs扩展成空格。
-f Make output that looks vaguely like an ed script but has changes in the order they appear in the file.
将输出格式化成ed的脚本。
-F regexp
In context and unified format, for each hunk of differences, show some of the last preceding line
that matches regexp.
在上下文和统一模式中，对于每个差异块，显示和"regexp"相匹配的前面行。
--forward-ed
Make output that looks vaguely like an ed script but has changes in the order they appear in the file.
-h This option currently has no effect; it is present for Unix compatibility.
-H
--speed-large-files
Use heuristics to speed handling of large files that have numerous scattered small changes.
使用启发式算法加速处理大文件中许多分散的小改变。
--horizon-lines=lines
Do not discard the last lines lines of the common prefix and the first lines lines of the common suffix.
不要丢弃最后的行数
-i Ignore changes in case; consider upper- and lower-case letters equivalent.
忽略大小写的区别
-I regexp
Ignore changes that just insert or delete lines that match regexp.
忽略和"regexp"匹配的行
--ifdef=name
Make merged if-then-else format output, conditional on the preprocessor macro name.
对指定了"name"的进行宏扩展输出
--ignore-all-space
Ignore white space when comparing lines.
忽略空格
--ignore-blank-lines
Ignore changes that just insert or delete blank lines.
忽略空行
--ignore-case
Ignore changes in case; consider upper- and lower-case to be the same.
忽略大小写
--ignore-matching-lines=regexp
Ignore changes that just insert or delete lines that match regexp.
忽略"regexp"指定的匹配行的改变
--ignore-space-change
Ignore changes in amount of white space.
忽略空格
--initial-tab
Output a tab rather than a space before the text of a line in normal or context format. This causes
the alignment of tabs in the line to look normal.
在标准或上下文格式中，在输出的文本前用Tab代替空格。
-l Pass the output through pr to paginate it.
-L label
--label=label
Use label instead of the file name in the context format and unified format headers.
在上下文和统一格式头中，使用标签来代替文件名
--left-column
Print only the left column of two common lines in side by side format.
--line-format=format
Use format to output all input lines in in-then-else format.
--minimal
Change the algorithm to perhaps find a smaller set of changes.This makes diff slower (sometimes
much slower).
-n Output RCS-format diffs; like -f except that each command specifies the number of lines affected.
-P When comparing directories, if a file appears only in the second directory of the two, treat it as
present but empty in the other.
-N
--new-file
In directory comparison, if a file is found in only one directory, treat it as present but empty in
the other directory.
在路径比较中，如果发现文件只在一个路径中存在，则认为它在另一个路径下为空
--new-group-format=format
Use format to output a group of lines taken from just the second file in if-then-else format.
--new-line-format=format
Use format to output a line taken from just the second file in if-then-else format.
--old-group-format=format
Use format to output a group of lines taken from just the first file in if-then-else format.
--old-line-format=format
Use format to output a line taken from just the first file in if-then-else format.
--paginate
Pass the output through pr to paginate it.
-r
--recursive
When comparing directories, recursively compare any subdirectories found.
比较目录时，对子目录进行递归
--rcs Output RCS-format diffs; like -f except that each command specifies the number of lines affected.
--report-identical-files
-s Report when two files are the same.
-S file
When comparing directories, start with the file file. This is used for resuming an aborted compari-
son.
比较目录时，指定起始的文件为"file"。它通常用来重启一个失败的比较
--from-file=file
Compare file to all operands. file can be a directory.
对文件进行所有操作
--to-file=file
Compare all operands to file. file can be a directory.
--sdiff-merge-assist
Print extra information to help sdiff. sdiff uses this option when it runs diff. This option is
not intended for users to use directly.
-p
--show-c-function
Show which C function each change is in.
--show-function-line=regexp
In context and unified format, for each hunk of differences, show some of the last preceding line
that matches regexp.
--side-by-side
Use the side by side output format.
--starting-file=file
When comparing directories, start with the file file. This is used for resuming an aborted compari-
son.
--suppress-common-lines
Do not print common lines in side by side format.
-t Expand tabs to spaces in the output, to preserve the alignment of tabs in the input files.
-T Output a tab rather than a space before the text of a line in normal or context format. This causes
the alignment of tabs in the line to look normal.
--text Treat all files as text and compare them line-by-line, even if they do not appear to be text.
-u Use the unified output format.
--unchanged-group-format=format
Use format to output a group of common lines taken from both files in if-then-else format.
--unchanged-line-format=format
Use format to output a line common to both files in if-then-else format.
--unidirectional-new-file
When comparing directories, if a file appears only in the second directory of the two, treat it as
present but empty in the other.
-u Use the unified output format.
使用统一输出格式
--unchanged-group-format=format
Use format to output a group of common lines taken from both files in if-then-else format.
--unchanged-line-format=format
Use format to output a line common to both files in if-then-else format.
--unidirectional-new-file
When comparing directories, if a file appears only in the second directory of the two, treat it as
present but empty in the other.
-U lines
--unified[=lines]
--text Treat all files as text and compare them line-by-line, even if they do not appear to be text.
-U lines
--unified[=lines]
Use the unified output format, showing lines (an integer) lines of context, or three if lines is not
given. For proper operation, patch typically needs at least two lines of context.
-v
--version
Output the version number of diff.
-w Ignore white space when comparing lines.
-W columns
--width=columns
Use an output width of columns in side by side format.
-x pattern
When comparing directories, ignore files and subdirectories whose basenames match pattern.
-X file
When comparing directories, ignore files and subdirectories whose basenames match any pattern contained in file.
-y Use the side by side output format.
SEE ALSO
cmp(1), comm(1), diff3(1), ed(1), patch(1), pr(1), sdiff(1).
DIAGNOSTICS
An exit status of 0 means no differences were found, 1 means some differences were found, and 2 means trou-
ble.
GNU Tools 22sep1993 DIFF(1)
