backup.sh

backup.sh is a POSIX compliant, modular and lightweight backup utility to save and encrypt your files. This tool is intended to be used on small scale UNIX environment such as VPS, small servers and workstations. backup.sh uses rsync, tar and openssl to copy, compress and encrypt the backup.

Installation

backup.sh consists in a single source file, to install it you can copy the script wherever you want. Alternatively, you can install the script, the default sources file and the man file using the following command:

$> sudo make install

This will copy backup.sh into /usr/local/bin/backup.sh, backup_sources.bk into /usr/local/etc/backup_sources.bk and backup.sh.1 into /usr/local/share/man/man1.

At this point you still need to install the dependencies:

• rsync
• tar
• openssl

Usage

To show the available options, you can run backup.sh --help, which will print out the following message:

backup.sh - POSIX compliant, modular and lightweight backup utility.

Syntax: ./backup.sh [-b|-e|-h]
options:
-b|--backup  SOURCES USER PASS  Backup folders from SOURCES file.
-e|--extract ARCHIVE PASS       Extract ARCHIVE using PASS.
-h|--help                       Show this helper.

As you can see, backup.sh supports two options: backup creation and archive extraction, the former requires root permissions, while the latter does not. Let us see them in details.

Backup creation

To specify the directories to backup, backup.sh uses an associative array called defined in a text file(called sources file) with the following syntax:

<LABEL>=<PATH>

Where <LABEL> is the name of the backup and <PATH> is its path. For example, if you want you back up /etc/nginx and /etc/ssh, add the following entries to the sources file:

nginx=/etc/nginx/
ssh=/etc/ssh/

backup.sh will create two folders inside the backup archive with the following syntax:

backup-<LABEL>-<YYYYMMDD>

In the previous example, this would be:

backup-nginx-<YYYYMMDD>
backup-ssh-<YYYYMMDD>

You can add as many entries as you want, just be sure to use the proper syntax. In particular, the sources file, should not includes:

• Spaces between the label and the equal sign;
• Empty lines;
• Comments.

You can find a sample sources file at backup_sources.bk(or at /usr/local/etc/backup_sources.bk).

After having defined the sources file, you can invoke backup.sh using the following syntax:

$> sudo ./backup.sh --backup <SOURCES_FILE> <USER> <ENCRYPTION_PASSWORD>

Where <SOURCES_FILE> is the sources file, <USER> is the home directory where you want the final backup and <ENCRYPTION_PASSWORD> is the password to encrypt the compressed archive.

In the previous example, this would be:

$> sudo ./backup.sh --backup sources.bk john badpw1234

The backup utility will begin to copy the files defined in the sources file:

Copying nginx(1/2)
Copying ssh(2/2)
Compressing and encrypting backup...
Elapsed time: 10 seconds.

After that, you will find the final backup archive in /home/john/backup-<HOSTNAME>-<YYYMMDD>.tar.gz.enc.

You can also use backup.sh from a crontab rule:

$> sudo crontab -e
30 03 * * 6 EKEY=$(cat /home/john/.ekey) /usr/local/bin/backup.sh -b /usr/local/etc/sources.bk john $EKEY

This will automatically run backup.sh every Saturday morning at 03:30 AM. In the example above, the encryption key is stored in a local file(with fixed permissions) to avoid password leaking in crontab logs. You can also adopt this practice while using the --extract option to avoid password leaking in shell history.

Archive extraction

backup.sh can also extract the encrypted backup archive using the following syntax:

$> ./backup.sh --extract <ENCRYPTED_ARCHIVE> <ARCHIVE_PASSWORD>

where <ENCRYPTED_ARCHIVE> is the encrypted backup and <ARCHIVE_PASSWORD> is the backup password.

For instance:

$> ./backup.sh -extract backup-<hostname>-<YYYMMDD>.tar.gz.enc badpw1234

This will create a new folder called backup.sh.tmp in your local directory. Be sure to rename any directory with that name to avoid collisions. From the previous example, you should have the following directories:

backup-nginx-<YYYYMMDD>
backup-ssh-<YYYYMMDD>

How does backup.sh work

TODO: explain backend(rsync) parameters.

Backup flow

Graph with:

1. loop through sources;
2. Copy each source in tmp dir;
3. Compress the archive and encrypt it.

Encryption

TODO: show file output of the backup

Unit tests

License