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README.md

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 # Backup
 A flexible backup script for backing up linux system using rsync, ssh, cron and other common shell commands.
 
+## Usage
+
+First add your settings at the top of the file and then add a cronjob to periodically execute the script. In the following paragraphs the settings will be explained.
+
+`SOURCES` is an array containing the paths to the folders that should be included in the backup.
+
+`TARGET` the absolute path to the folder where the backup will be saved to. If the `TOSSH` option is used, this should of course be the absolute path on the remote system.
+
+`EXCLUDEFROM` a path to a file containing folders and files that should be excluded from a backup.
+
+`MAILADRESS` if this option is a non empty string, the log of the backup will be send to the email adress contained in this string. For this to work the `mail` command must be set up properly.
+
+`LISTPACKAGES` if this option is set to a non empty string the log of the backup will contain a list of installed packages. For this command to work the `dpkg` command must be installed properly. 
+
+`LOG` the name of the log file.
+
+`RSYNCCONF` an array that contains additional rsync flags.
+
+`TOSSH` if this option is set to a non empty string, the backup will be saved on the remote host that this string refrences. **Attention:** Please set the `TOSSHUSER` and `TOSSHPORT` options as well, otherwise the script will probably fail to create a backup successfully. 
+
+`FROMSSH` if this option is set to a non empty string the folders refrenced in `SOURCES` will be fetched from the remote host refrenced by this string. **Attention:** Please set the `FROMSSHUSER` and `FROMSSHPORT` options as well otherwise the script might fail to create a backup successfully. 
+
+**Attention:** If both the `TOSSH` & `FROMSSH` options are set the script will fail!
+
+### Settings example
+
+```bash
+## General Settings
+SOURCES=(/home/example)           # What folder should be saved?
+TARGET="/home/backup/example"     # Where should they be saved? (absolute path!)
+EXCLUDEFROM="~/exclude.txt"       # What files are supposed to be excluded?
+MAILADRESS="example@example.com"  # To which email adress should the logs be sent?
+LISTPACKAGES=""                   # Change to non empty string to save a list of 
+                                  # installed packages!
+LOG=$0.log                        # Log file name & location
+RSYNCCONF=(--delete)              # Additional rsync flags  
+
+## SSH Settings
+TOSSH="my.backup.com"             # What ssh server stores the backups?
+FROMSSH=""                        # From what ssh server should the files be 
+                                  # backuped?
+                                  # For several reasons TOSSH and FROMSSH cannot
+                                  # be used at the same time!
+TOSSHUSER="example"               # The ssh user
+TOSSHPORT=22                      # The ssh port  
+FROMSSHUSER=""                    # The ssh user
+FROMSSHPORT=22                    # The ssh port
+```
+
+### Crontab example
+Create a backup every two hours:
+
+```bash
+0 */2 * * * ~/backup.sh
+```
+
 ## Inspiration
 
 - [Backup mit RSYNC](https://wiki.ubuntuusers.de/Skripte/Backup_mit_RSYNC/)