Day 5 - Advanced Linux Shell Scripting for DevOps Engineers with User Management

Create Directories Using Shell Script:

 ubuntu@ip-172-31-45-42:~/devops/ketan$ vim create_folders.sh

 #!/bin/bash
 if [ $# -ne 3 ]; then
   echo "Usage: $0 <string> <start_day> <end_day>"
   exit 1
 fi

 string="$1"
 start_day=$2
 end_day=$3

 if ! [[ "$start_day" =~ ^[0-9]+$ ]] || ! [[ "$end_day" =~ ^[0-9]+$ ]]; then
   echo "Start and end day should be integers."
   exit 1
 fi

 if [ "$start_day" -gt "$end_day" ]; then
   echo "Start day should be less than or equal to the end day."
   exit 1
 fi

 for ((i=start_day; i<=end_day; i++)); do
   directory_name="${string}-${i}"
   mkdir "$directory_name"
   echo "Created directory: $directory_name"
 done
 echo "Directories created successfully."

 ubuntu@ip-172-31-45-42:~/devops/ketan$ chmod 700 create_folders.sh

 ubuntu@ip-172-31-45-42:~/devops/ketan$ ./create_folders.sh "Day" 1 90
 Created directory: Day-1
 Created directory: Day-2
 Created directory: Day-3
 Created directory: Day-4
 Created directory: Day-5

 Directories created successfully.

Create a Script to Backup All Your Work:

 #!/bin/bash
 if [$# -ne 2]; then
         echo "Usage: $0 <source_directory> <target_directory>"
         exit 1
 fi

 source_dir="$1"
 target_dir="$2"
 # Validate if the source directory exists
 if [ ! -d "$source_dir" ]; then
         echo "Error: Source directory does not exist."
         exit 1

 fi
 # Validate if the target directory exists
 if [! -d "$target_dir" ]; then
         echo "Error: Target directory does not exist."
         exit 1
 fi

 # Create backup with current time stamp
 backup_file="$target_dir/backup_$(date +'%Y%m%d_%H%M%S').tar.gz"

 # Create the backup archive
 tar -cvf "$backup_file" -C "$source_dir" .
 echo "Backup created successfully at : $backup_file"

 ./create_backup.sh /path/to/source_directory /path/to/target_directory

 ubuntu@ip-172-31-45-42:~/devops$ mkdir backupfolder
 ubuntu@ip-172-31-45-42:~/devops$ ls
 backfolder  backupfolder  create_backup.sh  create_bakup.sh  ketan
 ubuntu@ip-172-31-45-42:~/devops$ ./create_backup.sh ketan backupfolder

 ./Day-22/
 ./Day-79/
 ./Day-84/
 ./Day-24/

 Backup created successfully at: backupfolder/backup_20240706_142339.tar.gz

Read About Cron and Crontab to Automate the Backup Script:

To add a cron job to execute the shell script at 11:00 PM every day, you must open the crontab file for the user that will run the cron job. Follow these steps to add the cron job:

1. Open the crontab file for editing crontab -e

2.    0 23  * /path/to/your/shell/script.sh /path/to/source_directory /path/to/target_directory
   

   Replace "/path/to/your/shell/script.sh" with the actual path to your shell script file. Also, replace "/path/to/source_directory" and "/path/to/target_directory" with the actual paths of the source and target directories.

3. Save the crontab file and exit the editor.

   The cron job will now run the shell script at 11:00 PM every day. It will create a backup with the current timestamp in the specified target directory.

Read About User Management:

Linux includes a built-in user management system to create, modify, and delete users.

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

     sudo useradd username
   

    ubuntu@ip-172-31-45-42:~/devops$ sudo useradd ketanhiray
    ubuntu@ip-172-31-45-42:~/devops$ cat /etc/passwd
   
    ketanhiray:x:1005:1007::/home/ketanhiray:/bin/sh
   

2. To modify user permissions, we can use the following command:

    ubuntu@ip-172-31-45-42:~/devops$ chmod 700 ketan
   

   This command will give the user username read, write, and execute permissions to the directory directory.

3. To delete a user, we can use the following command:

     sudo userdel username
   

Post Your Progress:

Mastering Advanced Linux Shell Scripting opens up a world of possibilities for DevOps engineers. Automating repetitive tasks and efficiently managing users can enhance productivity and streamline operations. I'm thrilled to have honed these skills and am eager to put them into practice in real-world projects!

Remember to like, comment, and share this post if you find it helpful, so we can inspire and support each other in our DevOps journey!