Month: February 2024

Shell script to create a new user and add their SSH public key to an Ubuntu VM

Below is a shell script that creates a new user and adds their SSH public key to an Ubuntu VM:

#!/bin/bash

# Function to create a new user and add SSH public key
create_user_and_add_ssh_key() {
    username=$1
    ssh_key_path=$2

    # Create user
    sudo adduser --disabled-password --gecos "" $username

    # Create .ssh directory if not exists
    sudo -u $username mkdir -p /home/$username/.ssh

    # Copy SSH public key to authorized_keys file
    cat $ssh_key_path >> /home/$username/.ssh/authorized_keys

    # Set proper permissions
    sudo chown -R $username:$username /home/$username/.ssh
    sudo chmod 700 /home/$username/.ssh
    sudo chmod 600 /home/$username/.ssh/authorized_keys
}

# Example usage
new_username="newuser"
ssh_key_path="/path/to/public_key.pub"

create_user_and_add_ssh_key $new_username $ssh_key_path

Make sure to replace newuser with the desired username and /path/to/public_key.pub with the path to the SSH public key file you want to add.

Save this script to a file (e.g., create_user_and_add_ssh_key.sh), make it executable (chmod +x create_user_and_add_ssh_key.sh), and then run it (./create_user_and_add_ssh_key.sh).

This script will create a new user without a password prompt and add their SSH public key to the authorized_keys file.

How do you set binlog retention period on MySQL?

In MySQL, you can control the retention period of binary log files using the expire_logs_days system variable. This variable determines how long binary log files are retained before they are automatically purged. Here’s how you can set up the binary log retention period:

  1. Check Current Configuration: You can check the current value of expire_logs_days by executing the following SQL query:sqlCopy codeSHOW VARIABLES LIKE 'expire_logs_days';
  2. Set Binary Log Retention Period: To set the binary log retention period to a specific number of days, you can use the following SQL statement:sqlCopy codeSET GLOBAL expire_logs_days = <number_of_days>; Replace <number_of_days> with the desired retention period.
  3. Update Configuration File (Optional): To make the change persistent across MySQL server restarts, you can add or update the expire_logs_days setting in your MySQL configuration file (e.g., my.cnf or my.ini). Add the following line:iniCopy codeexpire_logs_days = <number_of_days>
  4. Manually Purge Binary Logs (Optional): If you want to manually purge binary logs before the specified retention period, you can use the PURGE BINARY LOGS statement. For example, to purge logs older than 7 days, you can run:sqlCopy codePURGE BINARY LOGS BEFORE NOW() - INTERVAL 7 DAY; Be cautious while manually purging logs, as this operation cannot be undone.
  5. Restart MySQL Server (Optional): If you updated the configuration file, you might need to restart the MySQL server for the changes to take effect.

Keep in mind that setting a very short retention period may lead to potential data loss during certain recovery scenarios, so choose a value that aligns with your backup and recovery strategy. Additionally, be aware of the disk space implications of retaining binary logs for an extended period.