How to backup Linux system

The core of backing up a Linux system is to protect the system configuration, personal data, and installed software list. 1. The most critical backup files include: /home/ (user files), /etc/ (system configuration), /var/log/ (optional logs), /opt/ or /usr/local/ (custom programs). 2. Recommended tools include: rsync (flexible incremental backup), tar (packaging and compression), dd (whole disk image), timeshift (graphical interface restore point), rsync is recommended for daily use, tar is used for one-time backup, and dd is considered for system-level recovery. 3. To back up installed software, you need to record the installation history of the package manager. For example, use dpkg --get-selections > installed_packages.txt for Debian/Ubuntu, and dnf list installed > installed_packages.txt for Fedora/CentOS. 4. Regular backup can be automatically executed by writing scripts in conjunction with cron or systemd timer. For example, running the backup script at 2 a.m. every day, and it is recommended to verify backup integrity and recoverability regularly.

Backing up a Linux system is not difficult. The key is to know what data is important and what tools are appropriate. The core idea is: the system configuration, personal data, and installed software list must be preserved.

1. Which files are the most critical to back up?

Not all files are worth backing up, and some directories are created temporarily, such as /tmp and /run . Those that really need to focus on are:

• /home/ : The user’s personal files and settings are here
• /etc/ : System configuration files, such as network settings, user permissions, service configuration, etc.
• /var/log/ (optional): log file, useful when troubleshooting problems
• /opt/ or /usr/local/ (if you have installed the program yourself)

As for virtual file systems such as /dev , /proc , and /sys , no backup is required.

2. What tool is the most reliable?

There are several commonly used tools under Linux, each with its own applicable scenarios:

• rsync : flexible, supports incremental backup, suitable for local or remote synchronization. For example, use rsync -aAXv /home/ /media/backup/home/ to back up the entire home directory.

• tar : Packaging and compression, simple and direct, such as tar cvpzf backup.tar.gz --exclude=/backup.tar.gz /home/ package home into a file

• dd : Suitable for full-disk image backup, but takes up a lot of space. It is generally used to restore system-level disasters.

• timeshift : graphical interface tool, imitating "system restore point", suitable for desktop users

Which one you choose depends on your needs. rsync is recommended for daily regular backup. It is very convenient to package tar in one time. Only consider dd for system-level backup.

3. How to back up installed software?

Want to restore the original software after reinstalling the system? You only need to remember two things:

• Package manager installation records
• The path of the software you have manually installed (for example, under /opt/ )

Take Debian/Ubuntu as an example:

 dpkg --get-selections > installed_packages.txt

Fedora/CentOS users can use:

 dnf list installed > installed_packages.txt

In this way, the names of all currently installed software can be saved, and they can be restored in batches after reinstalling the system.

4. How to make regular backups more worry-free?

Manual backup is easy to forget, setting a scheduled task will make you feel more at ease:

• Write a backup script, such as running rsync at 2 am every day
• Cooperate with cron or systemd timer to achieve automatic execution
• It’s more secure to save backups to an external hard drive or remote server

Let’s take a simple cron example:

 0 2 * * * /path/to/backup_script.sh

In this way, a backup will be automatically run at two o'clock every morning.

Of course, remember to regularly check whether the backup is successful and whether it can be restored.

That's basically it. Backing up may seem troublesome, but in fact, as long as you plan the directory and tools clearly, regular maintenance is not complicated.

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