操作檔案和目錄

At this point, we are ready for some real work! This chapter will introduce the following commands:

此時此刻，我們已經準備好了做些真正的工作！這一章節將會介紹以下命令：

• cp – Copy files and directories

• mv – Move/rename files and directories

• mkdir – Create directories

• rm – Remove files and directories

• ln – Create hard and symbolic links

• cp — 複製檔案和目錄

• mv — 移動/重新命名檔案和目錄

• mkdir — 建立目錄

• rm — 刪除檔案和目錄

• ln — 建立硬連結和符號連結

These five commands are among the most frequently used Linux commands. They are used for manipulating both files and directories.

這五個命令屬於最常使用的 Linux 命令之列。它們用來操作檔案和目錄。

Now, to be frank, some of the tasks performed by these commands are more easily done with a graphical file manager. With a file manager, we can drag and drop a file from one directory to another, cut and paste files, delete files, etc. So why use these old command line programs?

現在，坦誠地說，用圖形檔案管理器來完成一些由這些命令執行的任務會更容易些。使用檔案管理器， 我們可以把檔案從一個目錄拖放到另一個目錄、剪貼和貼上檔案、刪除檔案等等。那麼， 為什麼還使用早期的命令列程式呢？

The answer is power and flexibility. While it is easy to perform simple file manipulations with a graphical file manager, complicated tasks can be easier with the command line programs. For example, how could we copy all the HTML files from one directory to another, but only copy files that do not exist in the destination directory or are newer than the versions in the destination directory? Pretty hard with a file manager. Pretty easy with the command line:

答案是命令列程式，功能強大靈活。雖然圖形檔案管理器能輕鬆地實現簡單的檔案操作，但是對於 複雜的檔案操作任務，則使用命令列程式比較容易完成。例如，怎樣拷貝一個目錄下所有的HTML檔案 ——這些檔案在目標目錄不存在或者版本比目標目錄的檔案更新——到目標目錄呢？ 要完成這個任務，使用檔案管理器相當難，使用命令列相當容易：

cp -u *.html destination

萬用字元

Before we begin using our commands, we need to talk about a shell feature that makes these commands so powerful. Since the shell uses filenames so much, it provides special characters to help you rapidly specify groups of filenames. These special characters are called wildcards. Using wildcards (which is also known as globbing) allow you to select filenames based on patterns of characters. The table below lists the wildcards and what they select:

在開始使用命令之前，我們需要介紹一個使命令列如此強大的 shell 特性。因為 shell 頻繁地使用 檔名，shell 提供了特殊字元來幫助你快速指定一組檔名。這些特殊字元叫做萬用字元。 使用萬用字元（也以檔名代換著稱）允許你依據字元的組合模式來選擇檔名。下表列出這些萬用字元 以及它們所選擇的物件：

Table 5-2 lists the most commonly used character classes:

表5-2列出了最常使用的字元類別：

Using wildcards makes it possible to construct very sophisticated selection criteria for filenames. Here are some examples of patterns and what they match:

藉助萬用字元，為檔名建構非常複雜的選擇標準成為可能。下面是一些型別匹配的範例:

Wildcards can be used with any command that accepts filenames as arguments, but we’ll talk more about that in Chapter 8.

接受檔名作為引數的任何命令，都可以使用萬用字元，我們會在第八章更深入地談到這個知識點。

Character Ranges

字元範圍

If you are coming from another Unix-like environment or have been reading some other books on this subject, you may have encountered the [A-Z] or the [a-z] character range notations. These are traditional Unix notations and worked in older versions of Linux as well. They can still work, but you have to be very careful with them because they will not produce the expected results unless properly configured. For now, you should avoid using them and use character classes instead.

如果你用過別的類別 Unix 系統的操作環境，或者是讀過這方面的書籍，你可能遇到過[A-Z]或 [a-z]形式的字元範圍表示法。這些都是傳統的 Unix 表示法，並且在早期的 Linux 版本中仍有效。 雖然它們仍然起作用，但是你必須小心地使用它們，因為它們不會產生你期望的輸出結果，除非 你合理地配置它們。從現在開始，你應該避免使用它們，並且用字元類別來代替它們。

Wildcards Work In The GUI Too

萬用字元在 GUI 中也有效

Wildcards are especially valuable not only because they are used so frequently on the command line, but are also supported by some graphical file managers.

萬用字元非常重要，不僅因為它們經常用在命令列中，而且一些圖形檔案管理器也支援它們。

• In Nautilus (the file manager for GNOME), you can select files using the Edit/Select Pattern menu item. Just enter a file selection pattern with wildcards and the files in the currently viewed directory will be highlighted for selection.

• In Dolphin and Konqueror (the file managers for KDE), you can enter wildcards directly on the location bar. For example, if you want to see all the files starting with a lowercase “u” in the /usr/bin directory, type “/usr/bin/u*” into the location bar and it will display the result.

• 在 Nautilus (GNOME 檔案管理器）中，可以透過 Edit/Select 模式選單項來選擇檔案。 輸入一個用萬用字元表示的檔案選擇模式後，那麼當前所瀏覽的目錄中，所匹配的檔名就會高亮顯示。

• 在 Dolphin 和 Konqueror（KDE 檔案管理器）中，可以在位址列中直接輸入萬用字元。例如， 如果你想檢視目錄 /usr/bin 中，所有以小寫字母 ‘u’ 開頭的檔案， 在位址列中敲入 ‘/usr/bin/u*‘，則 檔案管理器會顯示匹配的結果。

Many ideas originally found in the command line interface make their way into the graphical interface, too. It is one of the many things that make the Linux desktop so powerful.

最初源於命令列介面中的想法，在圖形介面中也適用。這就是使 Linux 桌面系統 如此強大的眾多原因中的一個

mkdir - 建立目錄

The mkdir command is used to create directories. It works like this:

mkdir 命令是用來建立目錄的。它這樣工作：

mkdir directory...

A note on notation: When three periods follow an argument in the description of a command (as above), it means that the argument can be repeated, thus:

注意表示法: 在描述一個命令時（如上所示），當有三個圓點跟在一個命令的引數後面， 這意味著那個引數可以重複，就像這樣：

mkdir dir1

would create a single directory named “dir1”, while

會建立一個名為”dir1”的目錄，而

mkdir dir1 dir2 dir3

would create three directokries named “dir1”, “dir2”, “dir3”.

會建立三個目錄，名為 dir1, dir2, dir3。

cp - 複製檔案和目錄

The cp command copies files or directories. It can be used two different ways:

cp 命令，複製檔案或者目錄。它有兩種使用方法：

cp item1 item2

to copy the single file or directory “item1” to file or directory “item2” and:

複製單個檔案或目錄”item1”到檔案或目錄”item2”，和：

cp item... directory

to copy multiple items (either files or directories) into a directory.

複製多個專案（檔案或目錄）到一個目錄下。

有用的選項和範例

Here are some of the commonly used options (the short option and the equivalent long option) for cp:

這裡列舉了 cp 命令一些有用的選項（短選項和等效的長選項）：

mv - 移動和重新命名檔案

The mv command performs both file moving and file renaming, depending on how it is used. In either case, the original filename no longer exists after the operation. mv is used in much the same way as cp:

mv 命令可以執行檔案移動和檔案命名任務，這依賴於你怎樣使用它。任何一種 情況下，完成操作之後，原來的檔名不再存在。mv 使用方法與 cp 很相像：

mv item1 item2

to move or rename file or directory “item1” to “item2” or:

把檔案或目錄 “item1” 移動或重新命名為 “item2”, 或者：

mv item... directory

to move one or more items from one directory to another.

把一個或多個條目從一個目錄移動到另一個目錄中。

有用的選項和範例

mv shares many of the same options as cp:

mv 與 cp 共享了很多一樣的選項：

rm - 刪除檔案和目錄

The rm command is used to remove(delete)files and directories:

rm 命令用來移除（刪除）檔案和目錄：

rm item...

where “item” is one or more files or directories.

“item”代表一個或多個檔案或目錄。

有用的選項和範例

Here are some of the common options for rm:

下表是一些普遍使用的 rm 選項：

Be Careful With rm!

小心 rm!

Unix-like operating systems such as Linux do not have an undelete command. Once you delete something with rm, it’s gone. Linux assumes you’re smart and you know what you’re doing.

類別 Unix 的作業系統，比如說 Linux，沒有復原命令。一旦你用 rm 刪除了一些東西， 它就消失了。Linux 假定你很聰明，你知道你在做什麼。

Be particularly careful with wildcards. Consider this classic example. Let's say you want to delete just the HTML files in a directory. To do this, you type:

尤其要小心萬用字元。思考一下這個經典的例子。假如說，你只想刪除一個目錄中的 HTML 檔案。輸入：

rm *.html

which is correct, but if you accidentally place a space between the “*” and the “.html” like so:

這是正確的，如果你不小心在「*」和 “.html” 之間多輸入了一個空格，就像這樣：

rm * .html

the rm command will delete all the files in the directory and then complain that there is no file called “.html”.

這個 rm 命令會刪除目錄中的所有檔案，還會抱怨沒有檔案叫做 “.html”。

Here is a useful tip. Whenever you use wildcards with rm (besides carefully checking your typing!), test the wildcard first with ls. This will let you see the files that will be deleted. Then press the up arrow key to recall the command and replace the ls with rm.

小貼士。 當你使用帶有萬用字元的rm命令時（除了仔細檢查輸入的內容外）， 先用 ls 命令來測試萬用字元。這會讓你看到將要被刪除的檔案是什麼。然後按下上箭頭按鍵，重新呼叫 剛剛執行的命令，用 rm 替換 ls。

ln — 建立連結

The ln command is used to create either hard or symbolic links. It is used in one of two ways:

ln 命令既可建立硬連結，也可以建立符號連結。可以用其中一種方法來使用它：

ln file link

to create a hard link, and:

建立硬連結，和：

ln -s item link

to create a symbolic link where “item” is either a file or a directory.

建立符號連結，”item” 可以是一個檔案或是一個目錄。

硬連結

Hard links are the original Unix way of creating links; symbolic links are more modern. By default, every file has a single hard link that gives the file its name. When we create a hard link, we create an additional directory entry for a file. Hard links have two important limitations:

與更加現代的符號連結相比，硬連結是最初 Unix 建立連結的方式。每個檔案預設會有一個硬連結， 這個硬連結給予檔名字。我們每建立一個硬連結，就為一個檔案建立了一個額外的目錄項。 硬連結有兩個重要侷限性：

1. A hard link cannot reference a file outside its own file system. This means a link may not reference a file that is not on the same disk partition as the link itself.

2. A hard link may not reference a directory.

1. 一個硬連結不能關聯它所在檔案系統之外的檔案。這是說一個連結不能關聯 與連結本身不在同一個磁碟分割槽上的檔案。

2. 一個硬連結不能關聯一個目錄。

A hard link is indistinguishable from the file itself. Unlike a symbolic link, when you list a directory containing a hard link you will see no special indication of the link. When a hard link is deleted, the link is removed but the contents of the file itself continue to exist (that is, its space is not deallocated) until all links to the file are deleted. It is important to be aware of hard links because you might encounter them from time to time, but modern practice prefers symbolic links, which we will cover next.

一個硬連結和檔案本身沒有什麼區別。不像符號連結，當你列出一個包含硬連結的目錄 內容時，你會看到沒有特殊的連結指示說明。當一個硬連結被刪除時，這個連結 被刪除，但是檔案本身的內容仍然存在（這是說，它所佔的磁碟空間不會被重新分配）， 直到所有關聯這個檔案的連結都刪除掉。知道硬連結很重要，因為你可能有時 會遇到它們，但現在實際中更喜歡使用符號連結，下一步我們會討論符號連結。

符號連結

Symbolic links were created to overcome the limitations of hard links. Symbolic links work by creating a special type of file that contains a text pointer to the referenced file or directory. In this regard, they operate in much the same way as a Windows shortcut though of course, they predate the Windows feature by many years ;-)

建立符號連結是為了克服硬連結的侷限性。符號連結生效，是透過建立一個 特殊型別的檔案，這個檔案包含一個關聯檔案或目錄的文字指標。在這一方面， 它們和 Windows 的快捷方式差不多，當然，符號連結早於 Windows 的快捷方式 很多年;-)

A file pointed to by a symbolic link, and the symbolic link itself are largely indistinguishable from one another. For example, if you write some something to the symbolic link, the referenced file is also written to. However when you delete a symbolic link, only the link is deleted, not the file itself. If the file is deleted before the symbolic link, the link will continue to exist, but will point to nothing. In this case, the link is said to be broken. In many implementations, the ls command will display broken links in a distinguishing color, such as red, to reveal their presence.

一個符號連結指向一個檔案，而且這個符號連結本身與其它的符號連結幾乎沒有區別。 例如，如果你往一個符號連結裡面寫入東西，那麼相關聯的檔案也被寫入。然而， 當你刪除一個符號連結時，只有這個連結被刪除，而不是檔案自身。如果先於符號連結 刪除檔案，這個連結仍然存在，但是不指向任何東西。在這種情況下，這個連結被稱為 壞連結。在許多實現中，ls 命令會以不同的顏色展示壞連結，比如說紅色，來顯示它們 的存在。

The concept of links can seem very confusing, but hang in there. We’re going to try all this stuff and it will, hopefully, become clear.

關於連結的概念，看起來很迷惑，但不要膽怯。我們將要試著練習 這些命令，希望，它變得清晰起來。

建立遊戲場（實戰演習）

Since we are going to do some real file manipulation, Let's build a safe place to “play” with our file manipulation commands. First we need a directory to work in. We’ll create one in our home directory and call it “playground.”

下面我們將要做些真正的檔案操作，讓我們先建立一個安全地帶， 來玩一下檔案操作命令。首先，我們需要一個工作目錄。在我們的 家目錄下建立一個叫做“playground”的目錄。

建立目錄

The mkdir command is used to create a directory. To create our playground directory we will first make sure we are in our home directory and will then create the new directory:

mkdir 命令被用來建立目錄。首先確定我們在我們的家目錄下，然後建立 playground 目錄：

[me@linuxbox ~]$ cd
[me@linuxbox ~]$ mkdir playground

To make our playground a little more interesting, Let's create a couple of directories inside it called “dir1” and “dir2”. To do this, we will change our current working directory to playground and execute another mkdir:

為了讓我們的遊戲場更加有趣，在 playground 目錄下建立一對目錄 ，分別叫做 “dir1” 和 “dir2”。更改我們的當前工作目錄到 playground，然後 執行 mkdir 命令：

[me@linuxbox ~]$ cd playground
[me@linuxbox playground]$ mkdir dir1 dir2

Notice that the mkdir command will accept multiple arguments allowing us to create both directories with a single command.

注意到 mkdir 命令可以接受多個引數，它允許我們用一個命令來建立這兩個目錄。

###　複製檔案

Next, Let's get some data into our playground. We’ll do this by copying a file. Using the cp command, we’ll copy the passwd file from the /etc directory to the current working directory:

下一步，讓我們輸入一些資料到我們的遊戲場中。我們可以透過複製一個檔案來實現目的。 我們使用 cp 命令從 /etc 目錄複製 passwd 檔案到當前工作目錄下：

[me@linuxbox playground]$ cp /etc/passwd .

Notice how we used the shorthand for the current working directory, the single trailing period. So now if we perform an ls, we will see our file:

請注意，我們使用命令末尾的一個圓點來簡化當前工作目錄的寫法。如果我們執行 ls 命令， 可以看到我們的檔案：

[me@linuxbox playground]$ ls -l
total 12
drwxrwxr-x 2  me  me   4096 2008-01-10 16:40 dir1
drwxrwxr-x 2  me  me   4096 2008-01-10 16:40 dir2
-rw-r--r-- 1  me  me   1650 2008-01-10 16:07 passwd

Now, just for fun, Let's repeat the copy using the “-v” option (verbose) to see what it does:

現在，僅僅是為了高興，重複操作複製命令，使用”-v”選項（詳細），看看它做了些什麼：

[me@linuxbox playground]$ cp -v /etc/passwd .
`/etc/passwd' -> `./passwd'

The cp command performed the copy again, but this time displayed a concise message indicating what operation it was performing. Notice that cp overwrote the first copy without any warning. Again this is a case of cp assuming that you know what you’re are doing. To get a warning, we’ll include the “-i” (interactive) option:

cp 命令再一次執行了複製操作，但是這次顯示了一條簡潔的資訊，指明它 進行了什麼操作。注意，cp 沒有警告，就重寫了第一次複製的檔案。這是一個案例， cp 會假設你知道自己在做什麼。如果希望得到警告的話，需要加入“-i”（互動）選項：

[me@linuxbox playground]$ cp -i /etc/passwd .
cp: overwrite `./passwd'?

Responding to the prompt by entering a “y” will cause the file to be overwritten, any other character (for example, “n”) will cause cp to leave the file alone.

在提示資訊後輸入”y”，檔案就會被重寫，輸入其它的字元（例如，”n”） cp 命令會保留原檔案。

移動和重新命名檔案

Now, the name “passwd” doesn’t seem very playful and this is a playground, so Let's change it to something else:

現在，”passwd” 這個名字，看起來不怎麼有趣，這是個遊戲場，所以我們給它改個名字：

[me@linuxbox playground]$ mv passwd fun

Let's pass the fun around a little by moving our renamed file to each of the directories and back again:

讓我們來傳送 fun 檔案，透過移動重新命名的檔案到各個子目錄， 然後再把它移回到當前目錄：

[me@linuxbox playground]$ mv fun dir1

to move it first to directory dir1, then:

首先，把 fun 檔案移動目錄 dir1 中，然後：

[me@linuxbox playground]$ mv dir1/fun dir2

to move it from dir1 to dir2, then:

再把 fun 檔案從 dir1 移到目錄 dir2, 然後：

[me@linuxbox playground]$ mv dir2/fun .

to finally bringing it back to the current working directory. Next, Let's see the effect of mv on directories. First we will move our data file into dir1 again:

最後，再把 fun 檔案帶回到當前工作目錄。接下來，來看看移動目錄的效果。 首先，我們先移動我們的資料檔案到 dir1 目錄：

[me@linuxbox playground]$ mv fun dir1

then move dir1 into dir2 and confirm it with ls:

然後移動 dir1到 dir2目錄，用 ls 來確認執行結果:

[me@linuxbox playground]$ mv dir1 dir2
[me@linuxbox playground]$ ls -l dir2
total 4
drwxrwxr-x 2 me me 4096 2008-01-11 06:06 dir1
[me@linuxbox playground]$ ls -l dir2/dir1
total 4
-rw-r--r-- 1 me me 1650 2008-01-10 16:33 fun

Note that since dir2 already existed, mv moved dir1 into dir2. If dir2 had not existed, mv would have renamed dir1 to dir2. Lastly, Let's put everything back:

注意：因為目錄 dir2 已經存在，mv 命令會把 dir1 移動到 dir2 目錄中。如果 dir2 不存在， mv 會把dir1重新命名為 dir2。最後，讓我們把所有的東西放回原處：

[me@linuxbox playground]$ mv dir2/dir1 .
[me@linuxbox playground]$ mv dir1/fun .

建立硬連結

Now we’ll try some links. First the hard links. We’ll create some links to our data file like so:

現在，我們試著建立連結。首先是硬連結。我們建立一些關聯我們 資料檔案的連結：

[me@linuxbox playground]$ ln fun fun-hard
[me@linuxbox playground]$ ln fun dir1/fun-hard
[me@linuxbox playground]$ ln fun dir2/fun-hard

So now we have four instances of the file “fun”. Let's take a look our playground directory:

所以現在，我們有四個檔案”fun”的範例。看一下目錄 playground 中的內容：

[me@linuxbox playground]$ ls -l
total 16
drwxrwxr-x 2 me  me 4096 2008-01-14 16:17 dir1
drwxrwxr-x 2 me  me 4096 2008-01-14 16:17 dir2
-rw-r--r-- 4 me  me 1650 2008-01-10 16:33 fun
-rw-r--r-- 4 me  me 1650 2008-01-10 16:33 fun-hard

One thing you notice is that the second field in the listing for fun and fun-hard both contain a “4” which is the number of hard links that now exist for the file. You’ll remember that a file will always have at least one because the file’s name is created by a link. So, how do we know that fun and fun-hard are, in fact, the same file? In this case, ls is not very helpful. While we can see that fun and fun-hard are both the same size (field 5), our listing provides no way to be sure. To solve this problem, we’re going to have to dig a little deeper.

注意到一件事，列表中，檔案 fun 和 fun-hard 的第二個欄位是”4”，這個數字 是檔案”fun”的硬連結數目。你要記得一個檔案至少有一個硬連結，因為檔案 名就是由連結建立的。那麼，我們怎樣知道實際上 fun 和 fun-hard 是同一個檔案呢？ 在這個例子裡，ls 不是很有用。雖然我們能夠看到 fun 和 fun-hard 檔案大小一樣 （第五欄位），但我們的列表沒有提供可靠的資訊來確定（這兩個檔案一樣）。 為了解決這個問題，我們更深入的研究一下。

When thinking about hard links, it is helpful to imagine that files are made up of two parts: the data part containing the file’s contents and the name part which holds the file’s name. When we create hard links, we are actually creating additional name parts that all refer to the same data part. The system assigns a chain of disk blocks to what is called an inode, which is then associated with the name part. Each hard link therefore refers to a specific inode containing the file’s contents.

當考慮到硬連結的時候，我們可以假設檔案由兩部分組成：包含檔案內容的資料部分和持有檔名的名字部分 ，這將有助於我們理解這個概念。當我們建立檔案硬連結的時候，實際上是為檔案建立了額外的名字部分， 並且這些名字都關聯到相同的資料部分。這時系統會分配一連串的磁碟塊給所謂的索引節點，然後索引節點與文 件名字部分相關聯。因此每一個硬連結都關係到一個具體的包含檔案內容的索引節點。

The ls command has a way to reveal this information. It is invoked with the “-i” option:

ls 命令有一種方法，來展示（檔案索引節點）的資訊。在命令中加上”-i”選項：

[me@linuxbox playground]$ ls -li
total 16
12353539 drwxrwxr-x 2 me  me 4096  2008-01-14  16:17  dir1
12353540 drwxrwxr-x 2 me  me 4096  2008-01-14  16:17  dir2
12353538 -rw-r--r-- 4 me  me 1650  2008-01-10  16:33  fun
12353538 -rw-r--r-- 4 me  me 1650  2008-01-10  16:33  fun-hard

In this version of the listing, the first field is the inode number and, as we can see, both fun and fun-hard share the same inode number, which confirms they are the same file.

在這個版本的列表中，第一欄位表示檔案索引節點號，正如我們所見到的， fun 和 fun-hard 共享一樣的索引節點號，這就證實這兩個檔案是同一個檔案。

建立符號連結

Symbolic links were created to overcome the two disadvantages of hard links: hard links cannot span physical devices and hard links cannot reference directories, only files. Symbolic links are a special type of file that contains a text pointer to the target file or directory.

建立符號連結的目的是為了克服硬連結的兩個缺點：硬連結不能跨越物理裝置， 硬連結不能關聯目錄，只能是檔案。符號連結是檔案的特殊型別，它包含一個指向 目標檔案或目錄的文字指標。

Creating symbolic links is similar to creating hard links:

符號連結的建立過程相似於建立硬連結：

[me@linuxbox playground]$ ln -s fun fun-sym
[me@linuxbox playground]$ ln -s ../fun dir1/fun-sym
[me@linuxbox playground]$ ln -s ../fun dir2/fun-sym

The first example is pretty straightforward, we simply add the “-s” option to create a symbolic link rather than a hard link. But what about the next two? Remember, when we create a symbolic link, we are creating a text description of where the target file is relative to the symbolic link. It’s easier to see if we look at the ls output:

第一個例子相當直接，在 ln 命令中，簡單地加上”-s”選項就可以建立一個符號連結， 而不是一個硬連結。下面兩個例子又是怎樣呢？ 記住，當我們建立一個符號連結 的時候，會建立一個目標檔案在哪裡和符號連結有關聯的文字描述。如果我們看看 ls 命令的輸出結果，比較容易理解。

[me@linuxbox playground]$ ls -l dir1
total 4
-rw-r--r-- 4 me  me 1650 2008-01-10 16:33 fun-hard
lrwxrwxrwx 1 me  me    6 2008-01-15 15:17 fun-sym -> ../fun

The listing for fun-sym in dir1 shows that is it a symbolic link by the leading “l” in the first field and that it points to “../fun”, which is correct. Relative to the location of fun-sym, fun is in the directory above it. Notice too, that the length of the symbolic link file is 6, the number of characters in the string “../fun” rather than the length of the file to which it is pointing.

目錄 dir1 中，fun-sym 的列表說明了它是一個符號連結，透過在第一欄位中的首字元”l” 可知，並且它還指向”../fun”，也是正確的。相對於 fun-sym 的儲存位置，fun 在它的 上一個目錄。同時注意，符號連結檔案的長度是6，這是字串”../fun”所包含的字元數， 而不是符號連結所指向的檔案長度。

When creating symbolic links, you can either use absolute pathnames:

當建立符號連結時，你既可以使用絕對路徑名：

ln -s /home/me/playground/fun dir1/fun-sym

or relative pathnames, as we did in our earlier example. Using relative pathnames is more desirable because it allows a directory containing symbolic links to be renamed and/or moved without breaking the links.

也可用相對路徑名，正如前面例題所展示的。使用相對路徑名更令人滿意， 因為它允許一個包含符號連結的目錄重新命名或移動，而不會破壞連結。

In addition to regular files, symbolic links can also reference directories:

除了普通檔案，符號連結也能關聯目錄：

[me@linuxbox playground]$ ln -s dir1 dir1-sym
[me@linuxbox playground]$ ls -l
total 16
...省略

移動檔案和目錄

As we covered earlier, the rm command is used to delete files and directories. We are going to use it to clean up our playground a little bit. First, Let's delete one of our hard links:

正如我們之前討論的，rm 命令被用來刪除檔案和目錄。我們將要使用它 來清理一下我們的遊戲場。首先，刪除一個硬連結：

[me@linuxbox playground]$ rm fun-hard
[me@linuxbox playground]$ ls -l
total 12
...省略

That worked as expected. The file fun-hard is gone and the link count shown for fun is reduced from four to three, as indicated in the second field of the directory listing. Next, we’ll delete the file fun, and just for enjoyment, we’ll include the “-i” option to show what that does:

結果不出所料。檔案 fun-hard 消失了，檔案 fun 的連結數從4減到3，正如 目錄列表第二欄位所示。下一步，我們會刪除檔案 fun，僅為了娛樂，我們會加入”-i” 選項，看一看它的作用：

[me@linuxbox playground]$ rm -i fun
rm: remove regular file `fun'?

Enter “y” at the prompt and the file is deleted. But Let's look at the output of ls now. Noticed what happened to fun-sym? Since it’s a symbolic link pointing to a now- nonexistent file, the link is broken:

在提示符下輸入”y”，刪除檔案。讓我們看一下 ls 的輸出結果。注意，fun-sym 發生了 什麼事? 因為它是一個符號連結，指向已經不存在的檔案，連結已經壞了：

[me@linuxbox playground]$ ls -l
total 8
drwxrwxr-x 2 me  me     4096 2008-01-15 15:17 dir1
lrwxrwxrwx 1 me  me        4 2008-01-16 14:45 dir1-sym -> dir1
drwxrwxr-x 2 me  me     4096 2008-01-15 15:17 dir2
lrwxrwxrwx 1 me  me        3 2008-01-15 15:15 fun-sym -> fun

Most Linux distributions configure ls to display broken links. On a Fedora box, broken links are displayed in blinking red text! The presence of a broken link is not, in and of itself dangerous but it is rather messy. If we try to use a broken link we will see this:

大多數 Linux 的發行版本配置 ls 顯示損壞的連結。在 Fedora 系統中，壞的連結以閃爍的 紅色文字顯示！損壞連結的出現，並不危險，但是相當混亂。如果我們試著使用 損壞的連結，會看到以下情況：

[me@linuxbox playground]$ less fun-sym
fun-sym: No such file or directory

Let's clean up a little. We’ll delete the symbolic links:

稍微清理一下現場。刪除符號連結：

[me@linuxbox playground]$ rm fun-sym dir1-sym
[me@linuxbox playground]$ ls -l
total 8
drwxrwxr-x 2 me  me    4096 2008-01-15 15:17 dir1
drwxrwxr-x 2 me  me    4096 2008-01-15 15:17 dir2

One thing to remember about symbolic links is that most file operations are carried out on the link’s target, not the link itself. rm is an exception. When you delete a link, it is the link that is deleted, not the target.

對於符號連結，有一點值得記住，執行的大多數檔案操作是針對連結的物件，而不是連結本身。 而 rm 命令是個特例。當你刪除連結的時候，刪除連結本身，而不是連結的物件。

Finally, we will remove our playground. To do this, we will return to our home directory and use rm with the recursive option (-r) to delete playground and all of its contents, including its subdirectories:

最後，我們將刪除我們的遊戲場。為了完成這個工作，我們將返回到 我們的家目錄，然後用 rm 命令加上選項(-r)，來刪除目錄 playground， 和目錄下的所有內容，包括子目錄：

[me@linuxbox playground]$ cd
[me@linuxbox ~]$ rm -r playground

Creating Symlinks With The GUI

用 GUI 來建立符號連結

The file managers in both GNOME and KDE provide an easy and automatic method of creating symbolic links. With GNOME, holding the Ctrl+Shift keys while dragging a file will create a link rather than copying (or moving) the file. In KDE, a small menu appears whenever a file is dropped, offering a choice of copying, moving, or linking the file.

檔案管理器 GNOME 和 KDE 都提供了一個簡單而且自動化的方法來建立符號連結。 在 GNOME 裡面，當拖動檔案時，同時按下 Ctrl+Shift 按鍵會建立一個連結，而不是 複製（或移動）檔案。在 KDE 中，無論什麼時候放下一個檔案，會彈出一個小選單， 這個選單會提供複製，移動，或建立連結檔案選項。

總結

We’ve covered a lot of ground here and it will take a while to fully sink in. Perform the playground exercise over and over until it makes sense. It is important to get a good understanding of basic file manipulation commands and wildcards. Feel free to expand on the playground exercise by adding more files and directories, using wildcards to specify files for various operations. The concept of links is a little confusing at first, but take the time to learn how they work. They can be a real lifesaver.

在這一章中，我們已經研究了許多基礎知識。我們得花費一些時間來全面地理解。 反覆練習 playground 例題，直到你覺得它有意義。能夠良好地理解基本檔案操作 命令和萬用字元，非常重要。隨意透過新增檔案和目錄來拓展 playground 練習， 使用萬用字元來為各種各樣的操作命令指定檔案。關於連結的概念，在剛開始接觸 時會覺得有點迷惑，花些時間來學習它們是怎樣工作的。它們能成為真正的救星。