linux-user-and-group-guide

Table of Contents

1. Search Words
2. Run Multiple Commands
3. Pipe Command
4. User Management
   • Create a User
   • View All Users
   • Verify User's Home Directory
   • Delete User
   • Create User Again
   • Change Username
   • Change User ID
   • Add Full Name
   • Change Home Directory
   • Change Shell Location
   • Set Password
   • Login and Check Password File
   • Manage Password Settings
5. Group Management
   • Add Group
   • Delete Group
   • Modify Group ID
   • Change User's Primary Group
   • Add User to Additional Groups
   • Remove User from Group
   • Add Multiple Users to a Group
   • Check Group Members
   • Add User to Multiple Groups
   • Change Group Name
6. Assign Permissions for User Management

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1) Search Words

Command: grep

Description: Searches the text file f1.txt for lines containing the word a (case-insensitive).

2) Run Multiple Commands

Description:

• Lists the files and directories in the current path.
• Creates a directory named abc.
• Creates an empty file named f30.
• Lists the updated files and directories.
• End of line ;

3) Pipe Command

Description:

• output of ls -l work as input of head -n 6

Description:

• Lists files with detailed information.
• Extracts the first 20 lines.
• Retrieves the last 5 of those 20 lines.
• Displays the first of the 5 lines.

4) User Management

Create a User

View All Users

Verify User's Home Directory

Delete User

Create User Again

useradd oggy cat /etc/passwd

Explanation of fields: oggy: Username X: Password placeholder 1001: User ID (UID) 1001: Group ID (GID) home/oggy: Home directory bin/bash: Default shell

Change Username

cat /etc/passwd

Change User ID

Add Full Name

Change Home Directory

cat /etc/passwd

Change Shell Location

Again change / to /bin/bash

Set Password

Login and Check Password File

• login as varun

when we login as user, '#' is chanage into '$'

'su' cammand use return to root

• password file are present in cat /etc/shadow

Fields explained:

Manage Password Settings

• chage -E "2024-09-23" varun for account expire
• chage -I 3 varun for password inactive

5) Group Management

Add Group

Delete Group

Modify Group ID

Change User's Primary Group

Add User to Additional Groups

Remove User from Group

Add Multiple Users to a Group

Check Group Members

Add User to Multiple Groups

Change Group Name

6) Assign Permissions for User Management

File to Edit: /etc/sudoers

Add the line to grant varun privileges: varun ALL=(ALL) ALL