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phosphor - Man Page

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.

--visual visual

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.

--font font-name

The X font to use.  Phosphor can take any font and scale it up to pixelate it.  The default is fixed.

--scale int

How much to scale the font up: in other words, the size in real pixels of the simulated pixels.  Default 6.

--ticks int

The number of colors to use when fading to black.  Default 20.

--delay usecs

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.

--program sh-command

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 www.kernel.org'
  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.

Terminal Emulation

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.

See Also

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).


Jamie Zawinski <jwz@jwz.org>, 27-Apr-99. Pty and vt100 emulation by Fredrik Tolf <fredrik@dolda2000.com>.


6.09-1.fc41 (11-Jun-2024) X Version 11 XScreenSaver manual