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

#Task1: Write a bash script createdirectories.sh. When the script is executed with given arguments (three rectory names, start number and end number) it creates a specified number of directories with a dynamic directory name.

#!/bin/bash

# Check if three arguments are provided
if [ "$#" -ne 3 ]; then
  echo "Usage: $0 <directory_name> <start_number> <end_number>"
  exit 1
fi

# Get the arguments
directory_name=$1
start_number=$2
end_number=$3

# Function to create directories
create_directories() {
  for ((i=start_number; i<=end_number; i++)); do
    dir_name="${directory_name}_${i}"
    mkdir -p "$dir_name"
    echo "Created directory: $dir_name"
  done
}

# Call the function
create_directories

To run the script:

1. Copy the above script into a text editor.

2. Save the file with the name createDirectories.sh

3. Open your terminal or command prompt.

4. Navigate to the directory where you saved the script.

5. Give execute permission to the script:

chmod 777 createDirectories.sh

1. Run the script with three arguments (directory name, start number, and end number):

./createDirectories.sh Day 1 90

The script will create 90 directories with names like Day_1, Day_2, and so on, up to Day_90. Each directory will be created in the current working directory.

#Task2: Create a Script to backup all your work done till now.

#!/bin/bash

# Check if the directory name is provided as an argument
if [ $# -ne 1 ]; then
  echo "Usage: $0 <directory_name>"
  exit 1
fi

# Extract the directory name from the argument
directory_name="$1"

# Validate if the directory exists
if [ ! -d "$directory_name" ]; then
  echo "Error: Directory '$directory_name' not found."
  exit 1
fi

# Create a backup directory with the current date and time
backup_dir="backup_$(date +%Y%m%d_%H%M%S)"

# Create the backup directory
mkdir "$backup_dir" || { echo "Failed to create backup directory."; exit 1; }

# Copy the content of the specified directory to the backup directory
cp -r "$directory_name"/* "$backup_dir" || { echo "Failed to create backup."; exit 1; }

echo "Backup created successfully at: $backup_dir"

Give execute permission to the script:

chmod 777 backup_script.sh

Run the script with the directory name you want to back up, for example:

./backup_script.sh my_directory

The script will create a backup of the specified directory, ensuring your important data is safe and secure.

#Task3: Read About Cron and Crontab, to automate the Script

Cron is the system's main scheduler for running jobs or tasks unattended. A command called crontab allows the user to submit, edit or delete entries to cron. A crontab file is a user file that holds the scheduling information.

You can use the following command to check the crontab list :-

crontab -l

If you want to create a new cron job you use the following command and enter in text editor to add a new cron entry.

crontab -e

It is possible to create jobs that you want to reoccur. This process is known as job scheduling. This process is handled by the cron service or a daemon called crond. and crontab -r to remove the current crontab configuration.

#Task4: Read about User Management

User is an entity that can manipulate files and perform serveral other operations. Each user in a Linux operating system is assigned an id. After installation of the OS, ID 0 is assigned to the root user. ID 1–999 are assigned to system users and ID from 1000 onwards are assigned to local user.

1. Command to get id of a user id username

2.Command to add a user sudo useradd username

3.Command to assign password to a user passwd username

4.Command to access user configuration cat /etc/passwd

5.Command to delete a user userdel -r username

6.For switching user account su username

#Task5: Create 2 users and just display their Usernames

To create a user, we can use the following command:

Create the first user:

sudo adduser demo1

Create the second user:

sudo adduser demo2

Display the usernames:

echo "User 1: user1"
echo "User 2: user2"

Thank you for reading!

Contact me at :

linkedin: https://www.linkedin.com/in/sutish-pradhan/

E-mail: psutish@gmail.com