如何在Linux终端中比较两个文本文件

柔情只为你懂 2021-07-26 12:12 408阅读 0赞

![Illustration of a terminal window on Linux][][Fatmawati Achmad Zaenuri/Shutterstock.com][Fatmawati Achmad Zaenuri_Shutterstock.com] [Fatmawati Achmad Zaenuri / Shutterstock.com][Fatmawati Achmad Zaenuri_Shutterstock.com]

Need to see the differences between two revisions of a text file? Then `diff` is the command you need. This tutorial shows you how to use `diff` on Linux and macOS, the easy way.

是否需要查看文本文件的两个修订版之间的差异？ 然后`diff`是您需要的命令。 本教程向您展示了如何在Linux和macOS上使用`diff`的简便方法。

## 深入了解差异 **(**Diving into diff**)** ##

The `diff` command compares two files and produces a list of the differences between the two. To be more accurate, it produces a list of the changes that would need to be made to the first file, to make it match the second file. If you keep that in mind you’ll find it easier to understand the output from `diff`. The `diff` command was designed to find differences between source code files and to produce an output that could be read and acted upon by other programs, such as the [patch][] command. In this tutorial, we’re going to look at the most useful human-friendly ways to use `diff`.

`diff`命令比较两个文件，并生成两个文件之间的差异列表。 为了更准确，它会生成一个列表，该列表需要对第一个文件进行更改以使其与第二个文件匹配。 如果牢记这一点，您会发现更容易理解`diff`的输出。 `diff`命令旨在查找源代码文件之间的差异，并生成可以被其他程序读取并作用的输出，例如[patch][]命令。 在本教程中，我们将研究使用`diff`的最有用的人性化方法。

Let’s dive right in and analyze two files. The order of the files on the command line determines which file `diff` considers to be the ‘first file’ and which it considers to be the “second file.” In the example below alpha1 is the first file, and alpha2 is the second file. Both files contain the [phonetic alphabet][] but the second file, alpha2, has had some further editing so that the two files are not identical.

让我们深入研究两个文件。 命令行上文件的顺序确定`diff`哪个文件被认为是“第一个文件”，哪个文件被认为是“第二个文件”。 在下面的示例中，alpha1是第一个文件，而alpha2是第二个文件。 这两个文件都包含[语音字母，][phonetic alphabet]但是第二个文件alpha2进行了进一步的编辑，以使两个文件不相同。

We can compare the files with this command. Type `diff`, a space, the name of the first file, a space, the name of the second file, and then press Enter.

我们可以使用此命令比较文件。 键入`diff` ，一个空格，第一个文件的名称，一个空格，第二个文件的名称，然后按Enter。

diff alpha1 alpha2

![Output from diff command with no options][]

How do we dissect that output? Once you know what to look for it’s not that bad. Each difference is listed in turn in a single column, and each difference is labeled. The label contains numbers either side of a letter, like `4c4`. The first number is the line number in alpha1, and the second number is the line number in alpha2.  The letter in the middle can be:

我们如何剖析该输出？ 一旦您知道要查找的内容，那还不错。 每个差异都在单列中依次列出，并标记每个差异。 标签包含字母两侧的数字，例如`4c4` 。 第一个数字是alpha1中的行号，第二个数字是alpha2中的行号。 中间的字母可以是：

*  **c**: The line in the first file needs to be changed to match the line in the second file.
    
    **c** ：需要更改第一个文件中的行以匹配第二个文件中的行。
 *  **d**: The line in the first file must be deleted to match the second file.
    
    **d** ：必须删除第一个文件中的行以匹配第二个文件。
 *  **a**: Extra content must be added to the first file to make it match the second file.
    
    **a** ：必须将额外的内容添加到第一个文件中，以使其与第二个文件匹配。

The `4c4` in our example tell us that line four of alpha1 must be changed to match line four of alpha2. This is the first difference between the two files that `diff` found.

在我们的示例中， `4c4`告诉我们必须更改alpha1的第四行以匹配alpha2的第四行。 这是`diff`找到的两个文件之间的第一个区别。

Lines that begin with `<` refer to the first file, in our example alpha1, and lines that start with `>` refer to the second file, alpha2. The line `< Delta` tells us that the word Delta is the content of line four in alpha1. The line `> Dave` tells us that the word Dave is the content of line four in alpha2. To summarise then, we need to replace Delta with Dave on line four in alpha1, to make that line match in both files.

在我们的示例alpha1中，以`<`开头的行引用第一个文件，而以`>`开头的行引用第二个文件alpha2。 `< Delta`行告诉我们单词Delta是alpha1中第四行的内容。 行`> Dave`告诉我们，单词Dave是alpha2中第四行的内容。 总结一下，我们需要在alpha1的第四行中用Dave替换Delta，以使这行在两个文件中都匹配。

The next change is indicated by the `12c12`. Applying the same logic, this tells us that line 12 in alpha1 contains the word Lima, but line 12 of alpha2 contains the word Linux.

下一个更改由`12c12`指示。 应用相同的逻辑，这告诉我们alpha1中的第12行包含单词Lima，而alpha2中的第12行包含单词Linux。

The third change refers to a line that has been deleted from alpha2. The label `21d20` is deciphered as “line 21 needs to be deleted from the first file to make both files synchronize from line 20 onwards.” The `< Uniform` line shows us the content of the line which needs to be deleted from alpha1.

第三次更改是指已从alpha2中删除的一行。 标签`21d20`被解读为“需要从第一个文件中删除第21行，以使两个文件从第20行开始进行同步。” `< Uniform`行向我们显示了需要从alpha1中删除的行的内容。

The fourth difference is labeled `26a26,28`. This change refers to three extra lines that have been added to alpha2. Note the `26,28` in the label. Two-line numbers separated by a comma represents a range of line numbers. In this example, the range is from line 26 to line 28. The label is interpreted as “at line 26 in the first file, add lines 26 to 28 from the second file.” We are shown the three lines in alpha2 that need to be added to alpha1. These contain the words Quirk, Strange, and Charm.

第四个差异标记为`26a26,28` 。 此更改是指已添加到alpha2的三行额外内容。 请注意标签中的`26,28` 。 用逗号分隔的两行数字表示一系列行号。 在此示例中，范围是从第26行到第28行。该标签被解释为“在第一个文件的第26行，从第二个文件中添加第26到28行。” 我们显示了alpha2中需要添加到alpha1中的三行。 这些包含单词Quirk，Strange和Charm。

## 活泼的单线 **(**Snappy One-Liners**)** ##

If you all you want to know is whether two files are the same, use the `-s` (report identical files) option.

如果您只想知道两个文件是否相同，请使用`-s` (报告相同文件)选项。

diff -s alpha1 alpha3

![Output of the diff command with -s option][]

You can use the `-q` (brief) option to get an equally terse statement about two files being different.

您可以使用`-q` (简短)选项来获得关于两个文件不同的同样简洁的语句。

diff -q alpha1 alpha2

![Output of the diff command with -q option][]

One thing to watch out for is that with two identical files the`-q` (brief) option completely clams up and doesn’t report anything at all.

需要注意的一件事是，对于两个相同的文件， `-q` (简短)选项会完全崩溃，并且根本不报告任何内容。

## 另一种观点 **(**An Alternative View**)** ##

The `-y` (side by side) option uses a different layout to describe the file differences. It is often convenient to use the `-W` (width) option with the side by side view, to limit the number of columns that are displayed. This avoids ugly wrap-around lines that make the output difficult to read. Here we have told `diff` to produce a side by side display and to limit the output to 70 columns.

`-y` (并排)选项使用不同的布局来描述文件差异。 在并排视图中使用`-W` (宽度)选项通常很方便，以限制显示的列数。 这样可以避免难看的环绕线，使输出难以阅读。 在这里，我们告诉`diff`并排显示，并将输出限制为70列。

diff -y -W 70 alpha1 alpha2

![Output of the diff command with side by side display][]

The first file on the command line, alpha1, is shown on the left and the second line on the command line, alpha2, is shown on the right. The lines from each file are displayed, side by side. There are indicator characters alongside those lines in alpha2 that have been changed, deleted or added.

命令行的第一个文件alpha1显示在左侧，命令行的第二个文件alpha2显示在右侧。 每个文件中的行并排显示。 在alpha2中已更改，删除或添加的那些行旁边有指示符。

*  **|**: A line that has been changed in the second file.
    
    **|** ：第二个文件中已更改的行。
 *  **<**: A line that has been deleted from the second file.
    
    **<** ：已从第二个文件中删除的行。
 *  **>**: A line that has been added to the second file that is not in the first file.
    
    **>** ：已添加到第二个文件的行，该行不在第一个文件中。

If you’d prefer a more compact side by side summary of the file differences, use the `--suppress-common-lines` option. This forces `diff` to list the changed, added or deleted lines only.

如果您希望文件差异的摘要更为紧凑，请使用`--suppress-common-lines`选项。 这将强制`diff`列出更改，添加或删除的行。

diff -y -W 70 --suppress-common-lines alpha1 alpha2

![Output of the diff command with --suppress-common-lines option][]

## 添加色彩飞溅 **(**Add a Splash of Color**)** ##

Another utility called `colordiff` adds color highlighting to the `diff` output. This makes it much easier to see which lines have differences.

另一个名为`colordiff`实用程序将颜色突出显示添加到`diff`输出中。 这样可以更轻松地查看哪些行具有差异。

Use `apt-get` to install this package onto your system if you’re using Ubuntu or another Debian-based distribution. On other Linux distributions, use your Linux distribution’s package management tool instead.

如果您使用的是Ubuntu或其他基于Debian的发行版，请使用`apt-get`将此软件包安装到系统上。 在其他Linux发行版上，请改用Linux发行版的程序包管理工具。

sudo apt-get install colordiff

Use `colordiff` just as you would use  `diff`.

就像使用`diff`一样，使用`colordiff` 。

![Output of the colordiff command with no options][]

In fact, `colordiff` is a wrapper for `diff`, and `diff` does all the work behind the scenes. Because of that, all of the `diff` options will work with `colordiff`.

实际上， `colordiff`是`diff`的包装，并且`diff`完成了幕后的所有工作。 因此，所有`diff`选项都可以与`colordiff`一起`colordiff` 。

![Output of the colordiff command with --suppress-common-lines option][]

## 提供一些背景 **(**Providing Some Context**)** ##

To find some middle ground between having all of the lines in the files displayed on the screen and having only the changed lines listed, we can ask `diff` to provide some context. There are two ways to do this. Both ways achieve the same purpose, which is to show some lines before and after each changed line. You’ll be able to see what’s going on in the file at the place where the difference was detected.

要在屏幕上显示文件的所有行和仅列出更改的行之间找到中间点，我们可以要求`diff`提供一些上下文。 有两种方法可以做到这一点。 两种方法都达到了相同的目的，即在每条更改的行之前和之后显示一些行。 您将能够在检测到差异的地方查看文件中正在发生的情况。

The first method uses the `-c` (copied context) option.

第一种方法使用`-c` (复制的上下文)选项。

colordiff -c alpha1 alpha2

![Output of colordiff with -c option][]

The `diff` output has a header. The header lists the two file names and their modification times. There are asterisks (`*`) before the name of the first file and dashes (`-`) before the name of the second file. Asterisks and dashes will be used to indicate which file the lines in the output belong to.

`diff`输出具有标头。 标头列出了两个文件名及其修改时间。 第一个文件名之前带有星号( `*` )，第二个文件名之前带有破折号( `-` )。 星号和破折号将用于指示输出中的行属于哪个文件。

A line of asterisks with 1,7 in the middle indicates we’re looking at lines from alpha1. To be precise, we’re looking at lines one to seven. The word Delta is flagged as changed. It has an exclamation point ( `!` ) alongside it, and it is red. There are three lines of unchanged text displayed before and after that line so we can see the context of that line in the file.

中间有1,7的星号线表示我们正在看的是alpha1的线。 确切地说，我们正在看第一到第七行。 单词Delta被标记为已更改。 它旁边有一个感叹号( `!` )，它是红色的。 在该行之前和之后显示三行未更改的文本，因此我们可以在文件中看到该行的上下文。

The line of dashes with 1,7 in the middle tells us we’re now looking at lines from alpha2. Again, we’re looking at lines one to seven, with the word Dave on line four flagged as being different.

中间有1,7的虚线表示我们现在正在查看alpha2中的线。 同样，我们要看的是第一行到第七行，第四行上的Dave这个词被标记为不同。

Three lines of context above and below each change is the default value. You can specify how many lines of context you want `diff` to provide. To do this, use the `-C` (copied context) option with a capital “C” and provide the number of lines you’d like:

每次更改上方和下方的三行上下文是默认值。 您可以指定要`diff`提供多少行上下文。 为此，请使用`-C` (复制的上下文)选项并使用大写字母“ C”，并提供所需的行数：

colordiff -C 2 alpha1 alpha2

![Output of colordiff with -C 2 option][]

The second `diff` option that offers context is the `-u` (unified context) option.

提供上下文的第二个`diff`选项是`-u` (统一上下文)选项。

colordiff -u alpha1 alpha2

![Output of colordiff with -u option][]

As before, we have a header on the output. The two files are named, and their modification times are shown. There are dashes (`-`) before the name of alpha1 and plus signs (`+`) before the name of alpha2. This tells us that dashes will be used to refer to alpha1 and plus signs will be used to refer to alpha2. Scattered throughout the listing are lines that start with at signs (`@`). These lines mark the start of each difference. They also tell us which lines are being shown from each file.

和以前一样，我们在输出上有一个标头。 这两个文件已命名，并显示了它们的修改时间。 alpha1名称前有破折号( `-` )，alpha2名称前有加号( `+` )。 这告诉我们，破折号将用于指代alpha1，加号将用于指代alpha2。 整个列表中散布着以符号( `@` )开头的行。 这些行标志着每个差异的开始。 他们还告诉我们每个文件中正在显示哪些行。

We are shown the three lines before and after the line flagged as being different so that we can see the context of the changed line. In the unified view, the lines with the difference are shown one above the other. The line from alpha1 is preceded by a dash and the line from alpha2 is preceded by a plus sign. This display achieves in eight lines what the copied context display above took fifteen to do.

将显示标记为不同的一行之前和之后的三行，以便我们可以看到更改后的行的上下文。 在统一视图中，具有差异的线一个显示在另一个之上。 alpha1的行之前是破折号，而alpha2的行之前是加号。 该显示用八行代码完成了上面复制的上下文显示用十五步完成的工作。

As you’d expect, we can ask `diff` to provide exactly the number of lines of unified context we’d like to see. To do this, use the `-U` (unified context) option with a capital “U” and provide the number of lines you’d want:

如您所料，我们可以要求`diff`提供我们希望看到的统一上下文的行数。 为此，请使用`-U` (统一上下文)选项并使用大写字母“ U”，并提供所需的行数：

colordiff -U 2 alpha1 alpha2

![Output of colordiff with -U 2 option][]

## 忽略空格和大小写 **(**Ignoring White Space and Case**)** ##

Let’s analyze another two files, test4 and test5. These have the names six of superheroes in them.

让我们分析另外两个文件，test4和test5。 它们中有六个超级英雄的名字。

colordiff -y -W 70 test4 test5

![Output of colordiff on test4 and test5 files][]

The results show that `diff` finds nothing different with the Black Widow, Spider-Man and Thor lines. It does flag up changes with the Captain America, Ironman, and The Hulk lines.

结果表明， `diff`与“黑寡妇”，“蜘蛛侠”和“雷神”系列没有什么不同。 它确实标记了美国队长，钢铁侠和绿巨人系列的变化。

So what’s different? Well, in test5 Hulk is spelled with a lowercase “h,” and Captain America has an extra space between “Captain” and “America.” OK, that’s plain to see, but what’s wrong with the Ironman line? There are no visible differences. Here’s a good rule of thumb. If you can’t see it, the answer is white space. There’s almost certainly a stray space or two, or a tab character, at the end of that line.

那有什么不同呢？ 好吧，在test5中，绿巨人的拼写是小写的“ h”，而美国队长在“队长”和“美国”之间有一个多余的空格。 好的，这很明显，但是Ironman系列到底出了什么问题？ 没有明显的差异。 这是一个很好的经验法则。 如果看不到，答案是空格。 该行的末尾几乎可以肯定有一个或两个杂散空格或一个制表符。

If they don’t matter to you, you can instruct `diff` to ignore specific types of line difference, including:

如果它们对您而言无关紧要，则可以指示`diff`忽略特定类型的行差异，包括：

*  **-i**: Ignore differences in case.
    
    **-i** ：忽略大小写差异。
 *  **-Z**: Ignore trailing white space.
    
    **-Z** ：忽略尾随空白。
 *  **-b**: Ignore changes in the amount of white space.
    
    **-b** ：忽略空白量的变化。
 *  **-w**: Ignore all white space changes.
    
    **-w** ：忽略所有空格更改。

Let’s ask diff to check those two files again, but this time to ignore any differences in case.

让我们让diff再次检查这两个文件，但是这次忽略大小写的任何差异。

colordiff -i -y -W 70 test4 test5

![output from colordiff ignore case][]

The lines with “The Hulk” and “The hulk” are now considered a match, and no difference is flagged for lowercase “h.” Let’s ask `diff` to also ignore trailing white space.

现在将带有“绿巨人”和“绿巨人”的行视为匹配项，并且小写字母“ h”没有区别。 让我们要求`diff`也忽略尾随空格。

colordiff -i -Z -y -W 70 test4 test5

![Output from colordiff ignore trailing white space][]

As suspected, trailing white space must have been the difference on the Ironman line because `diff` no longer flags a difference for that line. That leaves Captain America. Let’s ask `diff` to ignore case and to ignore *all* white space issues.

疑似，铁人行上的空白一定是差异，因为`diff`不再标记该行的差异。 剩下美国队长。 让我们要求`diff`忽略大小写并忽略*所有*空白问题。

colordiff -i -w -y -W 70 test4 test5

![Output from colordiff ignore all white space][]

By telling `diff` to ignore the differences that we’re not concerned about, `diff` tells us that, for our purposes, the files match.

通过告诉`diff`忽略我们不关心的`diff` ， `diff`告诉我们，出于我们的目的，文件是匹配的。

The `diff` command has many more options, but the majority of them relate to producing machine-readable output. These can be reviewed on the Linux [man page][]. The options we’ve used in the examples above will enable you to track down all the differences between versions of your text files, using the command line and human eyeballs.

`diff`命令具有更多选项，但其中大多数与生成机器可读输出有关。 这些可以在Linux [手册页][man page]上进行查看。 上面示例中使用的选项使您能够使用命令行和人眼来跟踪文本文件版本之间的所有差异。

> 翻译自: [https://www.howtogeek.com/410532/how-to-compare-two-text-files-in-the-linux-terminal/][https_www.howtogeek.com_410532_how-to-compare-two-text-files-in-the-linux-terminal]

[Illustration of a terminal window on Linux]: /images/20210726/0c4b4a95541f41b992f91498e32e2536.png
[Fatmawati Achmad Zaenuri_Shutterstock.com]: https://www.shutterstock.com/image-vector/linux-interface-screen-notebook-world-map-321627716
[patch]: http://man7.org/linux/man-pages/man1/patch.1p.html
[phonetic alphabet]: https://en.wikipedia.org/wiki/NATO_phonetic_alphabet
[Output from diff command with no options]: /images/20210726/6029a71d41d84e56ba33870bb6972a0e.png
[Output of the diff command with -s option]: /images/20210726/9845736b9c5c48b986662c9336379edf.png
[Output of the diff command with -q option]: /images/20210726/a74f4eee99c54c9e8faaf6222f18d36a.png
[Output of the diff command with side by side display]: /images/20210726/fe14348a74fd4ab59d94db618a7a7ce5.png
[Output of the diff command with --suppress-common-lines option]: /images/20210726/ef62f4c710764a1281169b85aeb2af2d.png
[Output of the colordiff command with no options]: /images/20210726/24a695c9edf24258a9eea5db204db131.png
[Output of the colordiff command with --suppress-common-lines option]: /images/20210726/287b1284face4403b94284d872bea916.png
[Output of colordiff with -c option]: /images/20210726/708d966dab2b421a9ca67c741e0214bb.png
[Output of colordiff with -C 2 option]: /images/20210726/03f0685a54ea4e10b46fbbd5b153f374.png
[Output of colordiff with -u option]: /images/20210726/bb3b3d3aaf454df899e13270d9b96e69.png
[Output of colordiff with -U 2 option]: /images/20210726/da5ff97ca9f34585a7cbff1d0a52094d.png
[Output of colordiff on test4 and test5 files]: /images/20210726/b4c6063abbd442f28f9ea96e4d8e24ed.png
[output from colordiff ignore case]: /images/20210726/251867fde0c641e6a865ea145fa76d4f.png
[Output from colordiff ignore trailing white space]: /images/20210726/fba160fef9014efcbeaaf91aa34c004a.png
[Output from colordiff ignore all white space]: /images/20210726/e59e86dbe5b14efdb1908dd5ec169a98.png
[man page]: http://man7.org/linux/man-pages/man1/diff.1.html
[https_www.howtogeek.com_410532_how-to-compare-two-text-files-in-the-linux-terminal]: https://www.howtogeek.com/410532/how-to-compare-two-text-files-in-the-linux-terminal/