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phosphor(6x) XScreenSaver manual phosphor(6x)


phosphor - simulates an old terminal with long-sustain phosphor


phosphor [--display host:display.screen] [--window] [--root] [--window-id number][--install] [--visual visual] [--font font] [--scale int] [--ticks int] [--delay usecs] [--program command] [--meta] [--esc] [--bs] [--del] [--fps]


The phosphor program draws text on the screen in a very large pixelated font that looks like an old low resolution dumb tty. The pixels flare and fade out as if the phosphor was very long-sustain. It is also a fully functional vt100 terminal emulator.


phosphor accepts the following options:

Draw on a newly-created window. This is the default.
Draw on the root window.
--window-id number
Draw on the specified window.
Install a private colormap for the window.
Specify which visual to use. Legal values are the name of a visual class, or the id number (decimal or hex) of a specific visual.
The X font to use. Phosphor can take any font and scale it up to pixelate it. The default is fixed.
How much to scale the font up: in other words, the size in real pixels of the simulated pixels. Default 6.
The number of colors to use when fading to black. Default 20.
The speed of the terminal: how long to wait between drawing each character. Default 50000, or about 1/20th second.
Launch the sub-program under a PTY, so that it can address the screen directly. This is the default.
Launch the sub-program at the end of a pipe: do not let it address the screen directly.
The command to run to generate the text to display. This option may be any string acceptable to /bin/sh. The program will be run at the end of a pty or pipe, and any characters that it prints to stdout will be printed on phosphor's window. The characters will be printed artificially slowly, as per the --delay option above. If the program exits, it will be launched again after 5 seconds.

For example:

phosphor --program 'ping'
phosphor --program 'ps -e'
phosphor --program 'od -txC -w6 /dev/random'
phosphor --program 'cat /dev/random'
phosphor --scale 2 --program 'top'
phosphor --scale 4 --program 'mtr'
phosphor --scale 4 --program 'emacs -nw -q -f life'
phosphor --scale 4 --program 'emacs -nw -q --eval "(hanoi 5)"'
If you have the festival(1) text-to-speech system installed, you can have it read the screen as phosphor prints it:

phosphor --program \
'xscreensaver-text | tee /dev/stderr | festival --tts'
You can also use phosphor as a lo-fi replacement for the xterm(1) and gnome-terminal(1) terminal emulators:

phosphor -delay 0 -program $SHELL
When the user types a key with the Alt or Meta keys held down, send an ESC character first. This is the default.
When Meta or Alt are held down, set the high bit on the character instead.
Swap Backspace and Delete. This is the default.
Do not swap Backspace and Delete.
Display the current frame rate and CPU load.


By default, phosphor allocates a pseudo-tty for the sub-process to run under. This has the desirable side effect that the program will be able to use ioctl(2) to fetch information about terminal parameters and window size, which many programs (such as top(1)) need to run properly. phosphor will also set the environment variable TERM to vt100 in the child process.

Any characters typed on the phosphor window will be passed along to the sub-process. (Note that this only works when running in "window" mode, not when running in --root mode under xscreensaver.)


to get the default host and display number.
to get the name of a resource file that overrides the global resources stored in the RESOURCE_MANAGER property.
The window ID to use with --root.
to inform the sub-process of the type of terminal emulation.


xscreensaver(1), xscreensaver-text(6x), fortune(1), apple2(6x), starwars(6x), fontglide(6x), ljlatest(6x), dadadodo(1), webcollage(6x), driftnet(1) EtherPEG, EtherPeek, console_codes(4).


Copyright © 1999 by Jamie Zawinski. Permission to use, copy, modify, distribute, and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation. No representations are made about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty.


Jamie Zawinski <>, 27-Apr-99. Pty and vt100 emulation by Fredrik Tolf <>.

6.09 (07-Jun-2024) X Version 11