Introduction

Managing users and files efficiently is a cornerstone of system administration in Linux. 🖥️🔧 This blog delves into the essential aspects of user and file management, ensuring you can effectively control access, maintain security, and organize your data.

User Management involves creating, modifying, and deleting user accounts, assigning permissions, and managing groups. It ensures that each user has the right level of access to system resources and can perform their tasks without compromising the system's security.
File Management covers creating, organizing, and maintaining files and directories. It includes setting permissions, managing file ownership, and ensuring data integrity. With the right file management practices, you can keep your system organized, secure, and efficient.

System level commands

Shows the platform name of the cli( command line interface).
```
 uname
```
Screen time with users active.
```
 uptime
```
Shows the date.
```
 date
```
Shows the user logged in with time and data.
```
 who
```
Shows only the user name only.
```
 whoami
```
Show users id's and their group id's.
```
 id
```
It refers to the super user or root user for the file access permission.
```
 sudo
```

Shutdown and reboot the system or instance.

 sudo shutdown #shutdown
 sudo reboot   #reboot

To install an application.

 sudo apt install 'application name' # finding the application  in system and download it
 sudo apt-get install 'application name' # It is like installing an application from a browser

Updates the application to install the applications.
```
sudo apt-get update
```

Note: There are many package managers like this apt for Ubuntu,rpm for Red Hat, dnf for Fedora, portage foe centos, ect.

Users and group management commands

To add a new user (-m stands to make user).
```
 sudo useradd -m 'username'
```
To set the password to the new user.
```
 sudo passwd 'username'
```
Switch to new user.
```
 sudo su 'username'
```
To come in primary user or original user.
```
 exit
```
To delete the user.
```
 sudo userdel 'username'
```

To create groups.

(Let's consider there are 2 groups Developers and Interns. Developers have 2 members d1 and d2. Interns have 3 members i1 i2,i3 respectively)

(-a stands to add flag and -m for multiple )

 # create the groups of developers and interns
 sudo groupadd developers
 sudo groupadd interns
 # to add members in these groups (method 1 adding one by one)
 sudo gpasswd -a d1 developers
 sudo gpasswd -a d2 developers
 sudo gpasswd -a i1 interns
 sudo gpasswd -a i2 interns 
 sudo gpasswd -a i3 interns
 # to add members in these groups (method 2 adding the above members in respectively groups)
 sudo gpasswd -m d1,d2 developers
 sudo gpasswd -m i1,i2,i2 interns

To delete group

 sudo groupdel 'groupname'System level commands

File permission commands

(Before understanding the file permission command please refer the below image thoroughly )

chmod Cheatsheet : r/linux

So, the above table says that drwxrwxrwx here d stands for directory and rwx represents read, write, and execute the file for user, group, and others respectively

Change mode for the file permissions.

 chmod 764  newfile.txt # 7 for user  (read,write and execute)
                        # 6 for group (read,write ,no execute)
                        # 4 for other (only read)

_rwxrw_r__ This represents the file permission of file newfile.txt remember to use command ls -l will show the file and directory permissions

To change ownership belongs to a file or directory.
```
 sudo chown 'username' newfile.txt
```
To change a group belongs to a file or directory.
```
 sudo chgrp 'groupname' newfile.txt
```

Compression commands

To zip the file or directory.
```
 zip 'zipfilename.zip' 'path/ / '
```
To unzip the file or directory.
```
 unzip 'zipfilename.zip'
```

Mastering User and File Management in Linux

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