It is highly recommended that you keep regular backups of any important files. Backups are often not limited to user files; they could include configuration files, databases, installed software, settings, and even an entire snapshot of a system.
Here, we'll guide you through some backup techniques for your Raspberry Pi system.
A sensible way to keep your home folder backed up is to use the
tar command to make a snapshot archive of the folder, and keep a copy of it on your home PC or in cloud storage. To do this, enter the following commands:
cd /home/ sudo tar czf pi_home.tar.gz pi
This creates a tar archive called
/home/. You should copy this file to a USB stick or transfer it to another machine on your network.
If you have MySQL databases running on your Raspberry Pi, it would be wise to keep them backed up too. To back up a single database, use the
mysqldump recipes > recipes.sql
This command will back up the
recipes database to the file
recipes.sql. Note that, in this case, no username and password have been supplied to the
mysqldump command. If you don't have your MySQL credentials in a
.my.cnf configuration file in your home folder, then supply the username and password with flags:
mysqldump -uroot -ppass recipes > recipes.sql
To restore a MySQL database from a dumpfile, pipe the dumpfile into the
mysql command. Provide credentials, if necessary, and the database name. Note that the database must exist, so create it first:
mysql -Bse "create database recipes" cat recipes.sql | mysql recipes
Alternatively, you can use the
pv command to see a progress meter as the dumpfile is processed by MySQL. This is not installed by default, so install with
sudo apt install pv. This command is useful for large files:
pv recipes.sql | mysql recipes
SD card image
It may be sensible for you to keep a copy of the entire SD card image, so you can restore the card if you lose it or it becomes corrupt. You can do this using the same method you'd use to write an image to a new card, but in reverse.
sudo dd bs=4M if=/dev/sdb of=raspbian.img
This will create an image file on your computer which you can use to write to another SD card, and keep exactly the same contents and settings. To restore or clone to another card, use
dd in reverse:
sudo dd bs=4M if=raspbian.img of=/dev/sdb
These files can be very large, and compress well. To compress, you can pipe the output of
gzip to get a compressed file that is significantly smaller than the original size:
sudo dd bs=4M if=/dev/sdb | gzip > raspbian.img.gz
To restore, pipe the output of
gunzip --stdout raspbian.img.gz | sudo dd bs=4M of=/dev/sdb
If you are using a Mac, the commands used are almost exactly the same, but
4M in the above examples should be replaced with
4m, with a lower case letter.
See more about installing SD card images.
You could write a Bash script to perform each of these processes automatically, and even have it performed periodically using cron.