rmt Command in Linux

Introduction

In this tutorial, we will delve into the Linux rmt command, an essential tool for system administrators. rmt, short for "remote magnetic tape," facilitates control over remote magnetic tape drives via a network connection, enabling seamless remote backups and restores. We'll explore how to integrate rmt with the tar command for efficient file backup and restoration across networks. Furthermore, we'll demonstrate how to automate this backup process using a Cron job.

This guide will cover: An introduction to the rmt command, performing backup and restore operations using rmt, and automating backups with rmt within a Cron Job. While rmt is primarily designed for managing remote tape drives, its versatility extends to other storage mediums such as disks or network-attached storage.

Introduction to the rmt Command

In this section, we will explore the rmt command, or "remote magnetic tape," within the Linux environment. The rmt command empowers systemadmins to manage remote magnetic tape drives across a network.

Let's begin by verifying the version of the rmt command installed on your system:

rmt --version

Example output:

rmt (GNU tar) 1.34
Copyright (C) 2021 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by John Gilmore and Jay Fenlason.

The rmt command is commonly used alongside the tar command to facilitate remote backup and restore operations. It enables control over a remote tape drive as if it were directly connected, simplifying backup management across networked systems.

Next, we will demonstrate how to use the rmt command for backing up and restoring files.

Backup and Restore Files Using rmt

This section focuses on utilizing the rmt command for backing up and restoring files over a network connection.

Firstly, let's create a sample file for our demonstration:

echo "This is a test file." > ~/project/test_file.txt

Now, let's employ the tar command in conjunction with rmt to create a backup of test_file.txt on a remote server:

sudo tar -cvf - ~/project/test_file.txt | rmt remote_host:/path/to/backup.tar

Breaking down the command:

  • tar -cvf -: Creates a tarball archive from the test_file.txt.
  • | rmt remote_host:/path/to/backup.tar: Pipes the tarball output to the rmt command, which then transmits the data to the specified remote host and saves it as backup.tar.

To restore the file from the remote backup, execute the following command:

rmt remote_host:/path/to/backup.tar | sudo tar -xvf -

This command retrieves the backup.tar file from the remote host and extracts its contents onto the local system.

Let's confirm that the file was successfully restored:

cat ~/project/test_file.txt

Example output:

This is a test file.

Excellent! You've successfully utilized the rmt command to backup and restore a file across a network.

Automating Backup with rmt in a Cron Job

In this final section, we will automate the backup process by integrating the rmt command with a Cron job.

First, we'll create a backup script that can be scheduled using Cron:

nano ~/project/backup.sh

Populate the script with the following content:

#!/bin/bash

## Set the remote host and backup directory
REMOTE_HOST="remote_host"
BACKUP_DIR="/path/to/backup"

## Backup the ~/project directory
sudo tar -czf - ~/project | rmt $REMOTE_HOST:$BACKUP_DIR/project_backup.tar.gz

Save the file and exit the editor.

Next, grant the script executable permissions:

chmod +x ~/project/backup.sh

Now, let's configure a Cron job to execute the backup script daily at 2:00 AM:

sudo crontab -e

Add the following line to the crontab file:

0 2 * * * /home/labex/project/backup.sh

This entry will execute the backup.sh script every day at 2:00 AM.

To test the backup process, you can manually run the script:

~/project/backup.sh

You should observe the backup being created on the designated remote host.

Congratulations! You've successfully automated the backup process using the rmt command and a Cron job.

Summary

This tutorial covered the Linux rmt command, a powerful tool for controlling remote magnetic tape drives over a network. We demonstrated how to check the rmt command's version and how to utilize it with the tar command for remote backups and restores. Specifically, we created a test file, backed it up to a remote server using rmt, and then restored it. This guide provided a practical understanding of leveraging the rmt command for efficient file management across networks, a core skill for any systemadmin dealing with legacy backup systems. Using the rmt command can provide a good solution for systemadmin in backing up data to a remote server.

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