6

Premise:

In a automotive gate automation scenario, I'm building a daemon, that I think to run in an Ubuntu headless server.

      linux headless host
    +----------------------+
    |                      |
    |                      |
    |                      |
    |   +--------------+   |
    |   | graphic card |   |
    +---+------+-------+---+
               | HDMI
               |
               |
+--------------v---------------+
|                              |
| Please contact the operator. |
| Push the emergency button    |
|                              |
|                              |
|                              |
|                              |
+------------------------------+
     high resolution screen

Goal:

The daemon program has to display some simple texts on a screen. Basically I just need to write text lines on a stdout, but with configurable BIG size fonts and geometry, as I could with a gnome terminal on a desktop environment. The point is that I would avoid to install a desktop environment just to solve the problem.

big text on terminal example

In the screenshot it's displayed the command clear && echo "Please contact operator" on a gnome terminal with different font size setting.

BTW, the reason of big font requirement is that displayed text will be read by truck drivers, at a distance of 1/2 meters from the computer monitor.

Notes:

  • A way I explored is to set the TTY character setting (at GRUB level). Unfortunately it doesn't appear to be a good option, because the font setting are very limited.

  • Reading Linux without graphical OS but with graphical resources, maybe framebuffer mode could be an option?

Question:

How can I display big front texts (so in a graphic mode) on a headless computer?

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4
  • I haven't tried this, but there is this link. I'm not sure if that's less limited than the GRUB method.
    – KGIII
    Commented Nov 2, 2020 at 18:23
  • yes, thx. I was read that article. the problem is that, I said in my note, the GRUB settings are very limited, not allowing a "full screen size" big font
    – Giorgio Robino
    Commented Nov 3, 2020 at 9:38
  • 1
    does this helps? askubuntu.com/a/579752/283843
    – αғsнιη
    Commented Nov 3, 2020 at 9:44
  • @αғsнιη That's smart! despite the name :-) I got nice result with: clear && printf "push the\nemergency\nbutton" | toilet -t --font=mono12
    – Giorgio Robino
    Commented Nov 3, 2020 at 10:48

1 Answer 1

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4

I answer myself just to share 3 solutions I found, listed from the worst to the best IMMO:

  1. using programs like toilet or figlet
clear && printf "push the\nemergency\nbutton" | toilet -t --font=mono12

                               ▄▄                            ▄▄
                               ██                    ██      ██
 ██▄███▄   ██    ██  ▄▄█████▄  ██▄████▄            ███████   ██▄████▄   ▄████▄
 ██▀  ▀██  ██    ██  ██▄▄▄▄ ▀  ██▀   ██              ██      ██▀   ██  ██▄▄▄▄██
 ██    ██  ██    ██   ▀▀▀▀██▄  ██    ██              ██      ██    ██  ██▀▀▀▀▀▀
 ███▄▄██▀  ██▄▄▄███  █▄▄▄▄▄██  ██    ██              ██▄▄▄   ██    ██  ▀██▄▄▄▄█
 ██ ▀▀▀     ▀▀▀▀ ▀▀   ▀▀▀▀▀▀   ▀▀    ▀▀               ▀▀▀▀   ▀▀    ▀▀    ▀▀▀▀▀
 ██




  ▄████▄   ████▄██▄   ▄████▄    ██▄████   ▄███▄██   ▄████▄   ██▄████▄   ▄█████▄  ▀██  ███
 ██▄▄▄▄██  ██ ██ ██  ██▄▄▄▄██   ██▀      ██▀  ▀██  ██▄▄▄▄██  ██▀   ██  ██▀    ▀   ██▄ ██
 ██▀▀▀▀▀▀  ██ ██ ██  ██▀▀▀▀▀▀   ██       ██    ██  ██▀▀▀▀▀▀  ██    ██  ██          ████▀
 ▀██▄▄▄▄█  ██ ██ ██  ▀██▄▄▄▄█   ██       ▀██▄▄███  ▀██▄▄▄▄█  ██    ██  ▀██▄▄▄▄█     ███
   ▀▀▀▀▀   ▀▀ ▀▀ ▀▀    ▀▀▀▀▀    ▀▀        ▄▀▀▀ ██    ▀▀▀▀▀   ▀▀    ▀▀    ▀▀▀▀▀      ██
                                          ▀████▀▀                                 ███


 ▄▄
 ██                    ██        ██
 ██▄███▄   ██    ██  ███████   ███████    ▄████▄   ██▄████▄
 ██▀  ▀██  ██    ██    ██        ██      ██▀  ▀██  ██▀   ██
 ██    ██  ██    ██    ██        ██      ██    ██  ██    ██
 ███▄▄██▀  ██▄▄▄███    ██▄▄▄     ██▄▄▄   ▀██▄▄██▀  ██    ██
 ▀▀ ▀▀▀     ▀▀▀▀ ▀▀     ▀▀▀▀      ▀▀▀▀     ▀▀▀▀    ▀▀    ▀▀
  1. Visualize an image on framebuffer

If the text is "static" (fixed) a solution is to display a bitmap on the framebuffer (an image containing the desired text).

An old but nice utility is fbi:

$ sudo apt install fbi

so having the image: fullscreen_text_image.PNG a fullscreen bitmap (e.g. in PNG format), here below the command (trick) to display the image for 5 seconds:

sudo fbi --noverbose --timeout 5 --once fullscreen_text_image.PNG
  1. framebuffer terminal emulation

fbterm is an old framebuffer terminal emulation program. The nice feature is that you can select a lot of options and by example you can have VERY HUGE font sizes:

sudo apt install fbterm

# run the terminal emulation on the framebuffer
fbterm --font-size=300

# remove prompt
PS1=''

# remove cursor
setterm --cursor off

# other settings (e.g. change background color)
# setterm --background red

# font change
# setfont /usr/share/consolefonts/Uni3-Terminus32x16.psf.gz

Running fbterm as shown, one can have a "normal" stdout, but with VERY BIG texts in high graphical quality! See picture:

enter image description here

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