Name: Shell 和命令行文法簡介 (Introduction to the Shell and Command-line Syntax)
Uploaded: 2025-11-02T02:36:50.000Z
Duration: 8 min 42 s

In this video, I'll provide an introduction to the shell and command line syntax on Oracle Linux.

在這支影片中，我會為大家介紹 Oracle Linux 的 shell 和指令列語法。

進階形容詞比較級句型

You'll learn what a shell is, what information the shell prompt provides, the structure of a command, how to view the manual pages, as well as handy shortcuts like tab completion, recalling a command, and

你會學到 shell 是什麼，提示字元會提供哪些資訊，指令的結構，如何查看手冊頁，還有像鍵盤自動完成、回溯指令和

Many of the applications we're familiar with use a GUI or graphical user interface to allow you to interact with the software.

我們熟悉的許多應用程式都使用 GUI 或圖形使用者介面來讓你操作軟體。

instead they use a CLI or command line interface which accepts text based input and provides text based output.

而是使用 CLI 或指令列介面，它接受文字輸入並提供文字輸出。

In Linux, you'll often be working from the command line to execute commands and interface with the operating system, and

在 Linux 中，你經常會在指令列上執行指令並與作業系統互動，

the environment you do this in is called the shell.

而你進行這些操作的環境就叫做 shell。

The default shell used with Oracle Linux is Bash.

Oracle Linux 預設使用的 shell 是 Bash。

BASH is one of the most common and a good place to start.

Bash 是最常見的 shell 之一，也是一個很好的入門點。

Let's take a look at the structure of the shell prompt by opening a terminal on your system.

我們來打開終端機，看看 shell 提示字元的結構。

If you're working with a Linux system that has a gui, you can access the terminal on the desktop.

如果你使用的是有 GUI 的 Linux 系統，你可以在桌面上找到終端機。

If your system doesn't have a gui, the first thing you'll see when you log in is the terminal, so you'll already be looking at the shell prompt.

如果你的系統沒有 GUI，登入後看到的第一個畫面就是終端機，所以你已經在看 shell 提示字元了。

The prompt shows us some important information.

這個提示字元會顯示一些重要的資訊給我們。

It has the username that we're logged in as and the name of the system that we're on, followed by the name of the directory we're currently working in.

它包含了我們登入的使用者名稱、我們所在的系統名稱，以及我們目前正在工作的目錄名稱。

In this case it shows a tilde, which means we're in the home directory of this user.

在這個例子中，它顯示了一個波浪符號，這表示我們在這個使用者的家目錄裡。

I won't go into details about the home directory or Linux file structure in this video, and

這個影片我不會深入探討家目錄或 Linux 的檔案結構，

don't worry about it too much for now, but

check out the video on working with files and directories for more information.

但你可以看看關於檔案和目錄操作的影片來獲取更多資訊。

提示字元會顯示一個錢幣符號。

If you're logged in as a normal user or if I switch to a different terminal session, it may have a hash sign if you're logged in as an administrative user.

如果你是普通使用者登入，或是切換到不同的終端機，如果是管理員使用者登入，則會顯示一個井字號。

在 Linux 中，管理員使用者稱為 root。

This is important to note because there are certain commands you can only run as root.

這點很重要，因為有些指令只能以 root 身分執行。

In documentation, you'll often see a command prefixed with either the dollar sign to indicate a normal user can run it, or the hash sign to indicate that you must run the command as the root user.

在文件裡，你常會看到指令前面加上錢幣符號，表示普通使用者可以執行；或是井字號，表示你必須以 root 使用者身分執行該指令。

So keep an eye out for these two symbols that covers the basics of the prompt.

所以請留意這兩個符號，這就涵蓋了提示字元的基礎。

Now let's take a look at the structure of a command.

The general structure you'll see is command options, arguments.

你看到的通用結構是：指令 選項 參數。

You'll always have a command this is what tells the program which function to perform.

你一定會有一個指令，這就是告訴程式要執行哪個功能的指令。

Then, depending on the command, you might also have one or more options, one or more arguments, or you might have both options and arguments.

然後，根據指令的不同，你可能會有一個或多個選項、一個或多個參數，或者你可能同時有選項和參數。

It really depends on the command and what you're trying to accomplish.

這真的要看你用什麼指令，還有你想達成什麼目標。

For example, I might use LS L downloads, where LS is the command, the L is the option, and

舉個例子，我可能會用 LS L downloads，其中 LS 是指令，L 是選項，

downloads is the argument, and if I hit enter, it returns the results of that command.

downloads 是參數，然後我按下 Enter，它就會回傳該指令的結果。

But what if I don't know what a particular command does or how to use it?

但如果我不知道某個指令是做什麼的，或是怎麼用呢？

Turns out there's built in documentation we can look at, called manual pages or man pages for short.

原來系統內建了我們可以查詢的說明文件，叫做手冊頁，簡稱 man pages。

It will show us more details about the structure of the command, the options available, and

它會顯示更多關於指令結構、可用的選項，以及

the arguments that we can use to view the man pages, type man space and then the command.

我們可以用來檢視 man pages 的參數的詳細資訊，輸入 man 空格，然後是指令。

In this case, let's look at the LS command I just ran, so I'll type man ls.

在這個例子中，讓我們來看看我剛剛執行的 LS 指令，所以我會輸入 man ls。

In some cases, a command may not have a man page, so instead you can usually get similar information by entering the command a space and then help.

在某些情況下，指令可能沒有 man page，這時候你通常可以輸入指令 空格，然後是 help 來取得類似的資訊。

LS does have a man page, so let's take a look at it by hitting enter at the top.

LS 有 man page，所以我們在最上面按下 Enter 來看看它。

Here it gives the command name and a brief description, telling us it lists directory contents.

這裡會顯示指令名稱和簡短描述，告訴我們它會列出目錄內容。

Then the synopsis section shows us the structure we can use to execute the command.

接著，說明部分會顯示我們可以執行指令的結構。

So the command LS can be followed by an option, and

所以指令 LS 後面可以接一個選項，然後

then it can also take an argument, in this case the name or path of a file.

它也可以接受一個參數，在這個例子中是檔案名稱或路徑。

The syntax here is giving us a little more information than might be obvious.

這裡的語法給我們的資訊比看起來的還要多一點。

The square brackets mean that this value is optional, so I can run this command using an option, but

方括號表示這個值是可選的，所以我可以執行這個指令並帶上一個選項，但是

Same with the argument, I can run it with or without specifying a file.

參數也是一樣，我可以指定檔案或不指定檔案來執行它。

Since both these are optional, this is telling us we can just run the LS command by itself and it'll work.

由於這兩者都是可選的，這表示我們可以直接執行 LS 指令，它就會正常運作。

The ellipses tell us that you can use multiples of these, so you can run it with multiple options and multiple files specified.

省略符號告訴我們可以使用這些選項的複數，所以你可以執行它並指定多個選項和多個檔案。

那麼，我們可以使用哪些選項呢？

Down here you'll see items with a dash and a double dash.

在這裡你會看到有單一破折號和雙重破折號的項目。

這些就是我們可以使用的選項。

The single dash followed by a letter is a shorthand version of the option.

單一破折號後面接著一個字母是該選項的簡寫版本。

So you can use a or all and it would do the same thing.

所以你可以使用 a 或 all，結果會是一樣的。

And real quick, if you need to go back, hit B and it will page up.

然後快速地，如果你需要往回，按 B 鍵它就會向上翻頁。

So here's the L option which says use a long listing Format.

所以這裡的 L 選項，它代表使用長格式的列表。

Normally LS just provides the name of the files and directories and doesn't give any more information.

一般來說，LS 只會顯示檔案和目錄的名稱，不會提供更多資訊。

But the L option will provide details like the size of the file, permissions, the date it was modified, and

但 L 選項會提供像是檔案大小、權限、修改日期等詳細資訊，

If I page down, you'll notice some of the options have this equal sign next to them.

如果我向下翻頁，你會注意到有些選項旁邊會有個等號。

That means this option takes an argument.

這表示這個選項需要一個引數。

So if I use the sort option, then I'd also need to tell it how to sort, such as by size or time to exit out of the man pages.

所以如果我使用 sort 選項，我就需要告訴它如何排序，例如依大小或時間，來離開 man pages。

Hit Q let's try running the LS command now that we know a little bit more about it.

按 Q 鍵，現在我們對 LS 指令多瞭解一些了，來試著執行它吧。

You can run LS alone and it'll just list the files and directories.

你可以單獨執行 LS，它只會列出檔案和目錄。

I can also run it with multiple options, so let's try L for long listing and A for all, which will show me hidden files.

我也可以執行它並帶入多個選項，所以我們來試試 L（長格式列表）和 A（全部），這會顯示我隱藏的檔案。

Note here that I've grouped shorthand options together so I don't have to do ls L A I can, and

這裡要注意，我把簡寫的選項組合在一起，這樣就不需要打 ls L A，

it'll provide the same results, but it's quicker to group them together.

它會得到一樣的結果，但組合起來比較快。

However, you can't group long versions together, so any options you have to list separately.

不過，你不能把長選項組合在一起，所以任何選項你都必須分開列。

For example, I can run LS l all sort size and I get results, but

例如，我可以執行 LS l all sort size，然後得到結果，但是

It thinks I'm trying to use an option allsort which doesn't exist, so be sure to keep the options separate.

它會認為我試圖使用一個不存在的 allsort 選項，所以請務必將選項分開。

There are a couple more syntax things within the man pages I want to point out.

man pages 裡還有幾個語法我想要提醒大家。

Let's look at the man page for a command called f allocate.

我們來看看一個叫做 fallocate 的指令的手冊頁。

This has some syntax we didn't see with the LS command.

它有一些我們在 LS 指令裡沒見過的語法。

Note these options are in square brackets, meaning they're optional, but

請注意，這些選項是用方括號括起來的，表示它們是可選的，

they're also separated by pipes, which are these vertical lines.

而且它們也用管道符號分隔，也就是這些垂直線。

The pipe means or, so you can use c or p or z.

管道符號的意思是「或」，所以你可以使用 c、p 或 z。

You can pick one of these, but you can't use them all at the same time.

你可以選擇其中一個，但不能同時使用全部。

This command also has options and arguments that aren't in brackets, meaning those are required.

這個指令還有一些不在方括號裡的選項和參數，這表示它們是必需的。

If you remember, LS had just one version of the command listed.

如果你記得的話，LS 指令列出的指令只有一個版本。

This has three, which is telling me I can run Fallocate in any of these three ways.

這裡有三個，這告訴我可以用這三種方式中的任何一種來執行 Fallocate。

Let's exit with q, and I'll show you a couple other useful things about the command line.

我們用 q 離開，然後我會再跟大家分享幾個關於指令列的實用技巧。

A handy trick is using tab completion, which means if I start typing something and hit tab, it will try to autocomplete with something valid.

一個實用的技巧是使用鍵盤自動完成，意思是我開始輸入一些東西然後按下 tab，它會試著自動完成成一個有效的指令。

Let's Say I want to look at what's in the Photos directory.

假設我想看看 Photos 目錄裡有什麼。

I can do LS space and a capital p. Then hit tab and it'll complete the rest.

我可以輸入 LS 空白鍵，然後一個大寫 P。接著按下 tab，它就會自動補齊剩下的部分。

So if I do LS with a lowercase p and hit tab, nothing happens because there's no file or directory here that starts with a lowercase p.

所以如果我用小寫 p 輸入 LS 然後按下 tab，什麼也不會發生，因為這裡沒有以小寫 p 開頭的檔案或目錄。

Now maybe I want to look at what's in the Documents directory.

現在，也許我想看看 Documents 目錄裡有什麼。

So if I do LS space, capital d and then hit tab, it's only going to give me do because we have two possibilities that both start with d and to see these possibilities, I can hit tab twice.

所以如果我輸入 LS 空白鍵，一個大寫 D，然後按下 tab，它只會給我 do，因為我們有兩個以 d 開頭的可能性，要查看這些可能性，我可以按兩次 tab。

It shows the documents and downloads directories.

它會顯示 documents 和 downloads 這兩個目錄。

So if I type c and then tab now it knows which one I want.

所以如果我輸入 c 然後按下 tab，它現在就知道我想要哪個了。

You can also use tab to look up commands you can't quite remember.

你也可以用 tab 來查找你不太確定的指令。