This repo guides you through the basics of file systems and the shell in a MacOS system.
We are all familiar with graphical user interfaces (GUI). They are easy to learn and suitable for “do the thing I want” by “click”. If you wish to do complex and purpose-specific things, you can use shell to express your instructions to the computer. Shell provides a simple language and a command-line interface to use it through.
The heart of a command-line interface is a read-evaluate-print loop (REPL). When you type a command and press Return or Enter, the shell reads your command, evaluates (or “executes”) it, prints the output of your command, loops back and waits for you to enter another command.
To learn how to use the shell, first we need to start a terminal session:
in Finder, open the Application -> Utilities folder, double-click Terminal.
You will see the hostname, followed by your current path and your name.
Last login: DDD MMM XX HH:MM:SS on ttysXXX
HOSTNAME:PATH USER$
The $ sign is a prompt, indicating you that the shell is waiting for commands. Your shell may use different text for the prompt. Most importantly: when typing commands, do not type the prompt, only the commands that follow it.
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Directory Structure and Filesystem: How can I move around on my computer and list files and directories? How can I create, copy, and delete files and directories?
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Text Wrangling: How can I edit files? How can I count the number of lines and sort contents of the files?
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Job Controls: How can I start a command in background and detach process in terminal?
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Working on EECS Servers: How can I run commands on EECS servers?
There are a couple of tools that are going to be handy:
1. TAB key
You probably want to type precise commands. For that you can use the embedded auto completion with your TAB_KEY.
For example,
HOSTNAME:PATH USER$ cd De[TAB_KEY]
HOSTNAME:PATH USER$ cd Desktop
2. Use history
It's good to know how to go back on your steps to take a look of what you have done.
- You can use the
historycommand:
HOSTNAME:PATH USER$ his[TAB_KEY]
HOSTNAME:PATH USER$ history
- Or you can go through your history using the
UP_KEY:
HOSTNAME:PATH USER$ [UP_KEY]
HOSTNAME:PATH USER$ history
3.Read the manual
Unix has an embedded manual. Just type man followed by the name of the command and you will get the manual for it. Use key for navigating throughout it and after that press q to quit.
Generally, commands take the form: <command> <options> <parameters>
<options> usually being of the form -x or --extract, <parameters> being based on their position.
4.Keyboard shortcuts
a. Control Process
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Ctrl+CKill whatever you are running -
Ctrl+ZPuts whatever you are running into a suspended background process.fgrestores it.
b. Control your entry
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Ctrl+DExit the current shell -
Ctrl+LClears the Screen, similar to the clear command -
Ctrl+UClears the line before the cursor position. If you are at the end of the line, clears the entire line. -
Ctrl+AGo to the beginning of the line you are currently typing on -
Ctrl+EGo to the end of the line you are currently typing on -
Ctrl+WDelete the word before the cursor -
Ctrl+KClear the line after the cursor -
Ctrl+RLet’s you search through previously used commands -
TABAuto-complete files and folder names
c. Control your terminal
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Cmd+NCreate a new terminal window -
Cmd+RIGHTandCmd+LEFTJump between windows -
Cmd+shift+wclose Terminal windows -
Cmd+tCreate a new terminal tab -
Cmd+Shift+right/leftJump between tabs -
Cmd+wClose Tab -
Cmd+upline up -
Cmd+downline down