unit 5

1. Explain the procedure of adding, removing and modifying user accounts in Linux with necessary commands and examples.

Managing user accounts in Linux involves adding, removing, and modifying user accounts. Here's a step-by-step procedure for performing these tasks using necessary commands and examples:

Adding a User Account:

1. To add a user account, you can use the useradd command. For example, to add a user named "john," you would run:

   sudo useradd john

   This creates a new user without specifying any additional options. The user will be created with default settings, including a home directory under /home/john.

2. To set a password for the new user, use the passwd command:

   sudo passwd john

   You will be prompted to enter and confirm the password for the user.

3. Optionally, you can specify additional options while creating the user. For instance, to set the user's home directory and specify their shell, you can use the -d and -s options:

   sudo useradd -d /home/john -s /bin/bash john

Modifying User Account Properties:

1. To modify user account properties, you can use the usermod command. For example, to change the user "john" to use the /bin/bash shell, run:

   sudo usermod -s /bin/bash john

2. To change the user's home directory, use the -d option:

   sudo usermod -d /new/home/directory john

3. You can also modify other user attributes using usermod, such as changing the user's primary group with the -g option or adding the user to additional groups with the -aG option.

Removing a User Account:

1. To remove a user account, use the userdel command followed by the username:

   sudo userdel john

   By default, userdel only removes the user account and not the user's home directory and files. To remove the user's home directory as well, use the -r option:

   sudo userdel -r john

Viewing User Account Information:

1. To view user account information, you can use the id command:

   id john

2. What do you means by disk quota? Write the steps of setting user disk quotas.Write the process of implementing Disk Quata in Linux.

Disk Quotas in Linux are a system for limiting the amount of disk space or the number of inodes that a user or a group of users can consume on a filesystem. This feature is useful in multi-user environments and on systems where you want to prevent users from using excessive disk resources.

Here are the steps to set user disk quotas and implement disk quotas in Linux:

Step 1: Check Kernel Support for Quotas:

Before enabling disk quotas, ensure that your Linux kernel supports quota features. Most modern kernels have quota support built-in. You can check if quotas are supported by examining the /proc/mounts file:

cat /proc/mounts | grep usrquota
cat /proc/mounts | grep grpquota

If you see output lines containing usrquota or grpquota, your kernel supports user and group quotas.

Step 2: Prepare the Filesystem:

You need to enable quota support on the filesystem where you want to enforce quotas. Typically, this is your user's home directory filesystem. Edit the /etc/fstab file to include the usrquota and grpquota options for the corresponding filesystem. For example:

/dev/sda1 /home ext4 defaults,usrquota,grpquota 0 0

After editing, remount the filesystem:

mount -o remount /home

Step 3: Install Quota Tools:

Ensure that the quota tools are installed on your system. If not, install them using your package manager. For example, on Debian/Ubuntu-based systems:

sudo apt-get install quota

Step 4: Initialize Quota Database:

Run the quotacheck command to initialize the quota database for the specified filesystem. Replace /home with the path to the filesystem you want to enable quotas on:

sudo quotacheck -cug /home

Step 5: Enable Quotas:

Enable quotas for the filesystem using the quotaon command:

sudo quotaon /home

Step 6: Set User and Group Quotas:

Use the edquota command to set user and group quotas. For example, to set user "john" with a soft limit of 1GB and a hard limit of 2GB on the /home filesystem:

sudo edquota -u john

This command will open an editor (usually nano or vi) where you can set the quota values.

Step 7: Check Quota Usage:

You can check the current quota usage for a user or group using the quota command:

quota -u john

Step 8: Monitoring and Maintenance:

To regularly check and update quotas, you can set up a cron job to run quotacheck and quotaon at specified intervals.

3. Explain the following user management commands with example of each.

useradd, usermod, groupadd, userdel 

1. useradd:

• The useradd command is used to create a new user account on a Linux system.

• Example: To create a new user named "jane," you would run:

  sudo useradd jane

  This command creates the user "jane" with default settings, including a home directory.

2. usermod:

• The usermod command is used to modify user account properties, such as changing the user's home directory or shell.

• Example: To change the shell for the user "jane" to /bin/bash, you would run:

  sudo usermod -s /bin/bash jane

  This command modifies the user's shell to /bin/bash.

3. groupadd:

• The groupadd command is used to create a new group on the system.

• Example: To create a new group named "developers," you would run:

  sudo groupadd developers

  This command creates the group "developers."

4. userdel:

• The userdel command is used to remove a user account from the system. By default, it only removes the user account, not the user's home directory or files.

• Example: To remove the user "jane," you would run:

  sudo userdel jane

  This command removes the user account "jane."

• To remove the user account along with the user's home directory and files, use the -r option:

  sudo userdel -r jane

  This command removes the user account "jane" and deletes their home directory and files.

4. Write the command Syntax for the following purpose

i) To create a user “Linux” with password “redhat”
ii) To change the password for that user to “fedora”
iii) To create a group “Hackers”
iv) After all assign the group “Hackers” for the user "“Linux”
V) After all provide comment name “Blackcat” and login shell “bash” for that user.
vi) Then assign the expiry date for that user account.
vii) To delete that group
viii) To remove that user

i) To create a user "Linux" with password "redhat":

sudo useradd Linux -p $(openssl passwd -1 redhat)

ii) To change the password for that user to "fedora":

sudo passwd Linux

iii) To create a group "Hackers":

sudo groupadd Hackers

iv) After all, assign the group "Hackers" for the user "Linux":

sudo usermod -aG Hackers Linux

V) After all, provide the comment name "Blackcat" and login shell "bash" for that user:

sudo usermod -c "Blackcat" -s /bin/bash Linux

vi) Then assign the expiry date for that user account:

sudo chage -E YYYY-MM-DD Linux

Replace YYYY-MM-DD with the desired expiration date.

vii) To delete that group:

sudo groupdel Hackers

viii) To remove that user:

sudo userdel -r Linux