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linux chapter 5.pptx lesson About introduction to linux

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Unit 5: Getting to Know the Command Line
Topics
1. Command Line Skills
2. Getting help commands
3. Working with files and Directories

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1. Command Line Skills
A) Command Line Interface (CLI)
The Command Line Interface (CLI), is a text-based interface to the computer, where
the user types in a command and the computer then executes it. The CLI
environment is provided by an application on the computer known as a terminal.
Accessing a Terminal
• There are many ways to access a terminal window. Some systems will boot
directly to a terminal.
• there are commonly two ways to access a terminal, a GUI-based terminal and a
virtual terminal( press on Crl+Alt+F1 to return GUI press on Crl+Alt+F7

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B) Prompt
• The prompt is designed to tell the user to enter a command.
• The structure of the prompt may vary between distributions, but will typically contain information about the
user and the system. Below is a common prompt structure:
sysadmin@localhost:~$
Systadmin : username
Local host: computer name
~ : current directory
$ : user type or Normal user .
C) Shell
• A shell is the interpreter that translates commands entered by a user into actions to be performed by the
operating system.
• The most commonly used shell for Linux distributions is called the BASH shell.
• The BASH shell also has other popular features:
1.Scripting: The ability to place commands in a file and execute the file, resulting in all of the commands being
executed. This feature also has some programming features, such as conditional statements and the ability to
create functions (AKA, subroutines).
2.Aliases: The ability to create short "nicknames" for longer commands.
3.Variables: Variables are used to store information for the BASH shell.

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D) Formatting commands
The typical format for a command is as follows:
command [options] [arguments] example : ls –l .d
Working with Options
• Options can be used with commands to expand or modify the way a command behaves.
• For example, you can use the -l option with the ls command to display more information about
the files that are listed. The ls -l command will list the files contained within the current
directory .
E) Command history
• When you execute a command in a terminal, the command is stored in a "history list". To view
the history list of a terminal, use the history command:
• sysadmin@localhost:~$ history or history –c
F) Introducing BASH shell variables
A BASH shell variable is a feature that allows you or the shell to store data.
To display the value of a variable, you can use the echo command. The echo command is used to
display output in the terminal; in the example below, the command will display the value of the
HISTSIZE variable: sysadmin@localhost:~$ HISTSIZE =500

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2. Getting Help commands
A) man Pages
Provides the a basic description of the purpose of the command, example : man ls
B) info Command/ learning guide and links
provides documentation on operating system commands and features.
example : info cal
C) --help
Provide basic information about command for example : find --help .
D) which Command/display the full path to the command in question:
searches for the location of a command by searching the PATH variable.
For example : which ls
E) type Command
The type command can be used to determine information about various commands.
Example : type which
F) whereis command. /specifically find commands and man pages.
search for the location of a command . Example : whereis date

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3.Working with Files and Directories
A) Introduction
When working in a Linux Operating System, you will need to know how to manipulate
files and directories. Some Linux distributions have GUI-based applications that allow you
to manage files, but it is important to know how to perform these operations via the
command line.
B) Understanding Files and Directories
Files are used to store data such as text, graphics , programs and devices.
Directories "folders") are used to provide a hierarchical organization structure.
This directory structure is called the filesystem by most Linux users.
To view the root filesystem, type ls /:

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C) Directory Path
A path allows you to specify the exact location of a directory. For the sound directory, the path
would be /etc/sound.
There are two types of paths : Absolute path and Relative Path .
Absolute path :
With an absolute path, you always provide directions to a directory starting from the root
directory. For example :cd /home/rooble/Desktop/arday.
Relative Path :
With relative path, provides directions using your current location .
For example : cd arday .
D) Directory and file listing commands
• Home Directory
Provides system users and represent it ~ ( tilde ) ex : cd ~
• Current Directory
is the directory where you are currently working in a terminal. To determine current directory
use pwd command .

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Changing Directories
If you want to change to a different directory, use the cd (change directory)
command. Cd Desktop .
Listing Files in a Directory
• The ls command (ls is short for list) can be used to display the contents of a
directory.
• Listing Colors
• There are many different types of files in Linux:
• Listing Hidden Files
To display all files, including hidden files, use the -a option to the ls command. Ls -a
Type Description
plain file A file that isn't a special file type; also called a normal file
directory A directory file (contains other files)
executable A file that can be run like a program
symbolic link A file that points to another file

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• Long Display Listing
There is information about each file example : ls –l
• Human Readable Sizes
When you display file sizes with the -l option to the ls command, you end up with
file sizes in bytes. For text files, a byte is 1 character. For example : ls -1h
• Listing Directories
When the command ls -d is used, it refers to the current directory. ls -d

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E) manipulating Directories
1. Creating directory
syntax : $mkdir dir name example :$kdir science
2. Create multiple directories :
Syntax :$mkdir dir1 dir2 dir3 example :$mkdir math economic
3. Entering the directory
syntax :$cd dirname example :$ cd science
4. Copy directory
Syntax :$ cp-r dir dir2 example :$cp science copy science
5. Renaming directory
Syntax :$mv dir1 dir2 example : $mv science cilmi
6. Deleting directory
syntax: $rmdir dirname- empty directory example :$rmdir science
Syntax : $rm-r dirname – is not empty example :$rm-r science

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F) Manipulating files
1.Creating file
Syntax : $cat>filename example : $cat>cashar.txt
Syntax : $touch filename –empty file example : $touch cashar2.txt
2. Appending contents to the file
Syntax : $cat>>filename example : $cat>>cashar2.txt
3.Concatenating multiple files :
Syntax : $cat file1 file2 >file3 example : $cat cashar.txt cashar2.txt >cashar3
4.Displaying the file content /open file
Syntax : $cat filename example : $cat cashar.txt
5.Renaming the file
Syntax : $mv filename example : $mv cashar.txt tijaabo.txt
6.Copying the file
Syntax : $cp source destination example : $cp cashar.txt copycashar.txt

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Cont …
7. Viewing the file type
Syntax : $ file filename example : $ file cashar.txt
8. Viewing the whole file
Syntax : $cat filename example : $cat cashar.txt or
Syntax : $less filename –one page example : $less cashar.txt
9. Viewing parts of a file
A- head command – first lines of the file
Syntax : $ head -3 filename example : $ head-3 cashar.txt
B-tail command – last lines of the file
Syntax : $ tail -3 filename example : $ last -3 cashar.txt
10. Deleting the file
Syntax : $ rm file example : $ rm cashar.txt
Syntax : $ rm file1 file 2 file example : $ rm cashar.txt cashar2.txt

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linux chapter 5.pptx lesson About introduction to linux

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