Posted onAug 13, 2024 • Originally published atyuscode.hashnode.dev

Chapter 2 - Basic Linux Commands

Introduction

Linux commands form the backbone of working with a Linux system. Mastering these commands allows you to efficiently navigate and manipulate files, directories, and system resources. In this chapter, we will cover the most essential commands for file and directory operations.

Commands for File and Directory Operations

ls

Thels command is used to list files and directories within the file system.

ls

ls -/: Lists all files and directories at the root of the file system.
```
ls /
```
ls -l: Provides a detailed listing including file permissions, number of links, owner, group, size, and timestamp.
```
ls-l
```
ls -a: Shows all files, including hidden files.
```
ls-a
```

cd

Thecd command is used to change the current directory.

cd[directory]

cd ~: Changes to the current user's home directory.
```
cd ~
```
cd ..: Moves up one directory level.
```
cd ..
```

pwd

pwd stands for "print working directory". This command displays the current directory.

pwd

touch

Thetouch command is used to create an empty file or update the timestamp of an existing file.

touchfile1.txt

cat

Thecat command is used to view the contents of a file.

cat[file_name]

cat file1.txt : Displays the content of file1.txt.
```
catfile1.txt
```

mkdir

Themkdir command is used to create new directories.

mkdir[directory_name]

To create a nested folder structure in Linux, you can use the mkdir command with the-p option like this:
```
mkdir-p directory-1/directory-2/directory-3/directory-4
```
The-p option tellsmkdir to create the parent directories as needed.

rmdir

Thermdir command is used to remove empty directories.

rmdir[directory_name]

cp

The cp command is used to copy files or directories.

cp[source][destination]

cp file1.txt /home/user: Copiesfile1.txt to the/home/user directory.
```
cpfile1.txt /home/user
```
cp -r dir1 /home/user : Recursively copies the directorydir1 and its contents to/home/user. Recursively as used in this case means to copy everything in the specified directory (dir1), including all its contents, subdirectories, and sub-subdirectories, and so on, all the way down.
```
cp-r dir1 /home/user
```

mv

Themv command is used to move or rename files or directories.

mv[source][destination]

mv file1.txt /home/user : Movesfile1.txt to the/home/user directory.
```
mvfile1.txt /home/user
```
mvold_name.txtnew_name.txt : Renamesold_name.txt tonew_name.txt.
```
mvold_name.txt new_name.txt
```

rm

Therm command is used to remove files or directories.

rm[file_name]

rm file1.txt : Deletesfile1.txt.
```
rmfile1.txt
```
rm -r dir1 : Recursively deletes the directorydir1 and its contents.
```
rm-r dir1
```

Globbing

Globbing is a way to find files on your computer that match a certain pattern. Think of it like a search function, but instead of searching for a specific word or phrase, you can use special characters called "wildcards" to match many files at once. Globbing is useful because it saves you time and effort when working with files. You can use globbing to:

Find and delete many files at once
Copy or move many files to a new location
Run scripts or programs on many files at once

Wildcards

In globbing, "wildcards" are special characters that represent one or more characters in a file name. Here are the most common wildcards:

* (asterisk): matches any characters (including none).
[abc] (square brackets): matches any character inside the brackets (e.g., a, b, or c).
[a-z] (square brackets with a range): matches any character in the range (e.g., a to z).

Below are example codes for each of the wildcards listed above:

* (asterisk):
```
ls*.txt
```
The command above lists all files ending with .txt
[abc] (square brackets):
```
ls[ab]*.txt
```
The command above lists files starting with a or b and ending with .txt (e.g., a_file.txt, b_file.txt)
[a-z] (square brackets with a range):
```
ls[a-z]*.txt
```
The command above lists files starting with any lowercase letter and ending with .txt (e.g., a_file.txt, z_file.txt)
NB: These examples use thels command to list files, but you can replacels with other commands likerm,cp, ormv to perform different actions on the matched files.

Conclusion

Mastering basic Linux commands is essential for navigating and managing a Linux system effectively. These commands form the foundation of working with files, directories, and system resources, empowering you to perform various tasks efficiently.

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