# Rotate Gnome Wallpaper using Systemd
- **Note:** Adjust paths as applicable to the desired OS.
- **Note:** The "$" represents the terminal prompt.
- **Note:** Verified to work on Arch Linux with Gnome v3.14.

## Installation Instructions

1. Download "gnome-rotate-wallpaper.service", "gnome-rotate-wallpaper.timer" and "gnome_rotate_wallpaper".
2. Move the 3 files to where Systemd user files are stored.
```bash
$ mv gnome-rotate-wallpaper.service gnome-rotate-wallpaper.timer /etc/systemd/user/
```
3. Move the BASH script "gnome_rotate_wallpaper".
```bash
$ mv gnome_rotate_wallpaper /usr/local/bin/
```
4. Set execute permissions.
```bash
$ chmod +x /usr/local/bin/gnome_rotate_wallpaper
```
5. Enable the timer.
```bash
$ systemctl --user enable gnome-rotate-wallpaper.timer
```
6. Verify the timer is enabled.
```bash
$ systemctl --user list-unit-files
gnome-rotate-wallpaper.service disabled
gnome-rotate-wallpaper.timer   enabled
2 unit files listed.
```
7. Start the timer.
```bash
$ systemctl --user start gnome-rotate-wallpaper.timer
```
8. Verify the timer has been started.
```bash
$ systemctl --user list-timers
NEXT                         LEFT    LAST                         PASSED UNIT                         ACTIVATES
Thu 2016-03-10 18:49:00 CST  1s left Thu 2016-03-10 18:48:56 CST  1s ago gnome-rotate-wallpaper.timer gnome-rotate-wallpaper.service
1 timers listed.
Pass --all to see loaded but inactive timers, too.
```

## User Configuration

### Change the default wallpaper directory.

1. Create the required directories.
```bash
$ mkdir  ~/.config/systemd ~/.config/systemd/user
```
2. Create the configuration file. Replace "username" with applicable value.
```bash
$ nano ~/.config/systemd/user/gnome-rotate-wallpaper.conf
```

    WALLPAPER_DIR=/home/username/Pictures/wallpaper

### Set the Interval to When the Wallpaper Changes.

Create the timer file and then change the "OnCalendar" value to the desired interval. Refer to [ArchLinux: systemd/Timers](https://wiki.archlinux.org/index.php/Systemd/Timers#Realtime_timer) for further details.

1. Create the required directories.
```bash
$ mkdir  ~/.config/systemd ~/.config/systemd/user
```
2. Create the configuration file.
```bash
$ nano ~/.config/systemd/user/gnome-rotate-wallpaper.timer
```

```
[Unit]
Description=Gnome rotate wallpaper

[Timer]
OnCalendar=*:0/1
Persistent=true
Unit=gnome-rotate-wallpaper.service

[Install]
WantedBy=gnome-rotate-wallpaper.service
```

## Available picture-options

- none
- wallpaper
- centered
- scaled
- stretched
- zoom
- spanned

## External Links

 * https://wiki.archlinux.org/index.php/Systemd/User
 * https://wiki.archlinux.org/index.php/Systemd/Timers
 * https://major.io/2015/02/11/rotate-gnome-3s-wallpaper-systemd-user-units-timers/
 * https://stackoverflow.com/questions/10374520/gsettings-with-cron