Day 5 Task: Advanced Linux Shell Scripting for DevOps Engineers with User Management.

• If you noticed that there are a total of 90 sub-directories in the directory '2023' of this repository. What did you think, how did I create 90 directories? Manually one by one or using a script, or a command? All 90 directories within seconds using a simple command.

---

Task 1 :

I have to do the same using Shell Script i.e. using either Loops or command with start day and end day variables using arguments.

---

Task 2 :

Create a Script to back up all your work done till now.

• Extracted tar file using command tar xf backups.sh

---

Task 3 :

Read About Cron and Crontab, to automate the backup Script.

Cron :

• Cron is a Linux utility that schedules tasks to run automatically at specified intervals.

• The tasks are defined in a crontab file which is a simple text file containing a list of commands meant to be run at specified times.

• Each line of the file represents a single cron job and follows a particular syntax.

Crontab :

• A crontab file is composed of six fields separated by spaces, that specify the schedule for a task to run.

• Minute (0-59)

• Hour (0-23)

• Days of the month (1-31)

• Month (1-12)

• Days of Week (0-7) Where 0 & 7 is Sunday

• Command to be executed.

COMMANDS FOR CRON

• crontab -e : To edit your crontab.

• crontab -l : To list the current crontab file.

• crontab -r : To remove your current crontab file.

• crontab -d : To delete a specific user crontab.

• crontab -l -u : To list specific user crontab.

Automate The Backup Script

• First, have Script "backup.sh".

• Here we will edit the crontab with the proper path in it.

• Now we will see the result by concatenate or cat the file.

---

User Management

In Linux, user management involves creating, modifying, and deleting user accounts. It also involves managing user permissions and groups. Here are some common commands and tools used for user management in Linux:

• useradd: This command is used to create new user accounts. For example, to create a new user account named "john", you would use the command "sudo useradd john".

• passwd: This command is used to set a password for a user account. For example, to set a password for the user account "john", you would use the command "sudo passwd john".

• usermod: This command is used to modify user accounts. For example, to change the home directory of the user account "john", you would use the command "sudo usermod -d /new/home/directory john".

• userdel: This command is used to delete user accounts. For example, to delete the user account "john", you would use the command "sudo userdel john".

• groups: This command is used to display the groups that a user belongs to. For example, to display the groups that the user "john" belongs to, you would use the command "groups john".

• useradd -G: This command is used to add a user to a group. For example, to add the user "john" to the group "developers", you would use the command "sudo useradd -G developers john".

• chgrp: This command is used to change the group ownership of a file or directory. For example, to change the group ownership of the file "file.txt" to the group "developers", you would use the command "sudo chgrp" developers file.txt".

These are just a few of the commands and tools used for user management in Linux. Proper user management is important for security and access control on a Linux system

---

Happy Learning :)