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title: Taking Backups with Duplicity

## date: 2015-05-16

I wanted to start taking backups for some time, but I haven’t had the time to do any research and set everything up. After reading another horror story that was saved by backups[a], I decided to start taking some backups.

=> https://www.reddit.com/r/linuxmasterrace/comments/35ljcq/couple_of_days_ago_i_did_rm_rf_in_my_home/ [a]

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After doing some research on backup options, I decided on duplicity[a]. The backups are compressed, encrypted and incremental, both saving space and ensuring security. It supports both local and ssh files(as well as many other protocols), so it has everything I need.

=> http://duplicity.nongnu.org/ [a]

I first took a backup into my external hard drive, then VPS. The main problem I encountered was that duplicity uses paramiko[a] for ssh, but it wasn’t able to negotiate a key exchange algorithm with my VPS. Luckily, duplicity also supports pexpect[b], which uses OpenSSH. If you encounter the same problem, you just need to tell duplicity to use pexpect backend by prepending your url with pexpect+, like pexpect+ssh://example.com.

=> https://github.com/paramiko/paramiko [a]
=> http://pexpect.sourceforge.net/pexpect.html [b]

Duplicity doesn’t seem to have any sort of configuration files of itself, so I ended up writing a small bash script to serve as a sort of configuration, and also keep me from running duplicity with wrong args. I kept forgetting to add an extra slash to file://, causing duplicity to backup my home directory into my home directory! :D

If anyone is interested, here’s the script:

```#!/bin/bash

if [[ $(id -u) != "0" ]]; then
    read -p "Backup should be run as root! Continue? [y/N]" yn
    case $yn in
        [Yy]*) break;;
        *) exit;;
    esac
fi


if [[ $1 = file://* ]]; then
    echo "Doing local backup."
    ARGS="--no-encryption"
    if [[ $1 = file:///* ]]; then
        URL=$1
    else
        echo "Use absolute paths for backup."
        exit 1
    fi
elif [[ $1 = scp* ]]; then
    echo "Doing SSH backup."
    ARGS="--ssh-askpass"
    URL="pexpect+$1"
else
    echo "Unknown URL, use scp:// or file://"
    exit 1
fi


if [[ -n "$1" ]]; then
    duplicity $ARGS --exclude-filelist /home/kaan/.config/duplicity-files /home/kaan "$URL/backup"
else
    echo "Please specify a location to backup into."
    exit 1
fi

```
