linux: added greeters to lightdm

wiki/linux/lightdm.md

@@ -8,6 +8,12 @@ It is available for both [X](/wiki/linux/x_window_system.md) and Wayland.
 
 On most linux distributions LightDM can be installed with the `lightdm` package.
 Additionally `lightdm-gtk-greeter` and `xorg-server-xephyr` are recommended.
+This setup will work with [LightDM-GTK-Greeter](#lightdm-gtk-greeter) which is the default 
+[greeter](#greeters) but others may be chosen.
+If that is the case `lightdm-gtk-greeter` does not have to be installed, but another one.
+For a guide on how to set the greeter navigate to the [greeter section](#greeters).
+This section will also discuss various other greeters like the
+[LightDM-Mini-Greeter](#lightdm-mini-greeter).
 
 This setup needs an `xsession`.
 An alternative to this is using `xinitrc` as an `xsession`.
@@ -38,3 +44,129 @@ system.
 systemctl enable lightdm.service`
 reboot
 ```
+
+## Greeters
+
+LightDM features the option to choose between many different greeters.
+This section focusses on various greeters.
+
+The greeter can be set with the option `greeter-session` under the section `[Seat:*]` in the file 
+`/etc/lightdm/lightdm.conf`.
+This will look similar to the following line.
+
+```txt 
+[Seat:*]
+
+greeter-session=lightdm-mini-greeter
+```
+
+If no `greeter-session` is set the default will fall back to the
+[LightDM-GTK-Greeter](#lightdm-gtk-greeter).
+
+### LightDM-GTK-Greeter
+
+The [LightDM-GTK-Greeter](https://github.com/Xubuntu/lightdm-gtk-greeter) is the default greeter 
+for LightDM.
+
+### LightDM-Mini-Greeter
+
+[LightDM-Mini-Greeter](https://github.com/prikhi/lightdm-mini-greeter) is a minimal greeter.
+
+For the LightDM-Mini-Greeter to work correctly some settings have to be set in the file
+`/etc/lightdm/lightdm-mini-greeter.conf`.
+The following lines show an example of this file.
+The most important changes have been done to set the `user` under `[greeter]` 
+and `background-image` under `[greeter-theme]`.
+The background image path can vary, but lightdm has to be able to access the 
+image.
+
+```txt
+# LightDM Mini Greeter Configuration
+#
+# To test your configuration out, run: lightdm --test-mode
+
+[greeter]
+# The user to login as.
+user = user
+# Whether to show the password input's label.
+show-password-label = true
+# The text of the password input's label.
+password-label-text = Password:
+# The text shown when an invalid password is entered. May be blank.
+invalid-password-text = Invalid Password
+# Show a blinking cursor in the password input.
+show-input-cursor = true
+# The text alignment for the password input. Possible values are:
+# "left", "center", or "right"
+password-alignment = left
+# The number of characters that should fit into the password input.
+# A value of -1 will use GTK's default width.
+# Note: The entered width is a suggestion, GTK may render a narrower input.
+password-input-width = -1
+# Show the background image on all monitors or just the primary monitor.
+show-image-on-all-monitors = false
+
+
+[greeter-hotkeys]
+# The modifier key used to trigger hotkeys. Possible values are:
+# "alt", "control" or "meta"
+# meta is also known as the "Windows"/"Super" key
+mod-key = meta
+# Power management shortcuts (single-key, case-sensitive)
+shutdown-key = s
+restart-key = r
+hibernate-key = h
+suspend-key = u
+
+
+[greeter-theme]
+# A color from X11's `rgb.txt` file, a quoted hex string(`"#rrggbb"`) or a
+# RGB color(`rgb(r,g,b)`) are all acceptable formats.
+
+# The font to use for all text
+font = "Sans"
+# The font size to use for all text
+font-size = 1em
+# The font weight to use for all text
+font-weight = bold
+# The font style to use for all text
+font-style = normal
+# The default text color
+text-color = "#eeeeee"
+# The color of the error text
+error-color = "#F8F8F0"
+# An absolute path to an optional background image.
+# The image will be displayed centered & unscaled.
+# Note: The file should be somewhere that LightDM has permissions to read
+#       (e.g., /etc/lightdm/).
+background-image = "/etc/lightdm/background.jpg"
+# The screen's background color.
+background-color = "#0e0f14"
+# The password window's background color
+window-color = "#282828"
+# The color of the password window's border
+border-color = "#555a63"
+# The width of the password window's border.
+# A trailing `px` is required.
+border-width = 2px
+# The pixels of empty space around the password input.
+# Do not include a trailing `px`.
+layout-space = 15
+# The character used to mask your password. Possible values are:
+# "-1", "0", or a single unicode character(including emojis)
+# A value of -1 uses the default bullet & 0 displays no characters when you
+# type your password.
+password-character = -1
+# The color of the text in the password input.
+password-color = "#eeeeee"
+# The background color of the password input.
+password-background-color = "#282828"
+# The color of the password input's border.
+# Falls back to `border-color` if missing.
+password-border-color = "#282828"
+# The width of the password input's border.
+# Falls back to `border-width` if missing.
+password-border-width = 2px
+# The border radius of the password input.
+password-border-radius = 0.341125em
+```