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stackinator
Asked: 2018-10-27 05:34:55 +0800 CST

Force GNOME Night Light to stay on and never turn off

  • 772

There's a manual option to set the times you want GNOME night light to be on and off. I want it always on.

The closest I can get is to set it to turn on at 00:00 and turn off at 23:59. But then at midnight it goes off for a minute which is annoying. Then I have to turn it back on through the settings. How do I force it "always on".

gnome display 18.04

4 Answers

  1. Best Answer

    The "native" way for Gnome Shell to always keep your nightlight color on involves to access some hidden options in dconf-editor. dconf-editor is not installed by default on Ubuntu 18.04. You may need to install it first.

    • Open dconf-editor and navigate to the key /org/gnome/settings-daemon/plugins/color/
    • Set night-light-schedule-automatic to false
    • Set night-light-schedule-from to 0, and night-light-schedule-to to 24 (or any value higher than this)

    You can also adjust your color temperature there.

    In Ubuntu versions later than 18.04, these settings are exposed in "Settings", under "Displays".

    • 22

  2. I was similarly looking for a way to keep it on at all times but didn't see a way through the GUI. The other answers work but I found a simpler way to enable it via terminal without having to install any additional tools:

    gsettings set org.gnome.settings-daemon.plugins.color night-light-enabled true
gsettings set org.gnome.settings-daemon.plugins.color night-light-schedule-automatic false
gsettings set org.gnome.settings-daemon.plugins.color night-light-schedule-from 0
gsettings set org.gnome.settings-daemon.plugins.color night-light-schedule-to 24
gsettings set org.gnome.settings-daemon.plugins.color night-light-temperature 5000

    To get an idea of temperature value ranges, Redshift uses default values of 3700 at night and 5500 during the day.

    • 7

  3. Another alternative is sct which you can install with sudo apt install sct.

    $ sct -h
Usage: sct [temperature]
Temperatures must be in a range from 1000-10000
If no arguments are passed sct resets the display to the default temperature (6500K)
If -h is passed sct will display this usage information
$

    Putting sct 3500 or whatever other value you prefer in your autostart should do it.

    • 6

  4. The question can be reframed to "How can I have screen color temperature at 5000 all the time?".

    In this case you can use xrandr to set the color temperature. From these notes:

    /* -----------------------------------------------------------------------------
    Dec 9, 2018 - Future Help Screen? Below taken from `sct` C source code:

/* cribbed from redshift, but truncated with 500K steps */
static const struct { float r; float g; float b; } whitepoints[] = {
    { 1.00000000,  0.18172716,  0.00000000, }, /* 1000K */
    { 1.00000000,  0.42322816,  0.00000000, },
    { 1.00000000,  0.54360078,  0.08679949, }, /* 2000K */
    { 1.00000000,  0.64373109,  0.28819679, },
    { 1.00000000,  0.71976951,  0.42860152, }, /* 3000K */
    { 1.00000000,  0.77987699,  0.54642268, },
    { 1.00000000,  0.82854786,  0.64816570, }, /* 4000K */
    { 1.00000000,  0.86860704,  0.73688797, },
    { 1.00000000,  0.90198230,  0.81465502, }, /* 5000K */
    { 1.00000000,  0.93853986,  0.88130458, },
    { 1.00000000,  0.97107439,  0.94305985, }, /* 6000K */
    { 1.00000000,  1.00000000,  1.00000000, },             /* 6500K */
    { 0.95160805,  0.96983355,  1.00000000, }, /* 7000K */
    { 0.91194747,  0.94470005,  1.00000000, },
    { 0.87906581,  0.92357340,  1.00000000, }, /* 8000K */
    { 0.85139976,  0.90559011,  1.00000000, },
    { 0.82782969,  0.89011714,  1.00000000, }, /* 9000K */
    { 0.80753191,  0.87667891,  1.00000000, },
    { 0.78988728,  0.86491137,  1.00000000, }, /* 10000K */
    { 0.77442176,  0.85453121,  1.00000000, },
};

----------------------------------------------------------------------------- */

    You can see 5000K is:

    { 1.00000000,  0.90198230,  0.81465502, }, /* 5000K */

    So you can use xrandr like this

    xrandr --output DP-1 --gamma 1:.90:.81

    Do this on startup and forget about Night Light or any other add on.

    Ironically looking at the code redshift (at night) mostly entails blue shift + green shift (reduction).

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