Redshift-GUI works very well indeed.
Years ago, before moving to Linux, I used to use f.Lux in Windoze. Under Linux, f.Lux is command-line only.....and a wee bit complicated to get right.
RedshiftGUI does much the same thing for Linux.....and, in fact, I personally prefer the interface to that of f.Lux. You can get this from SourceForge:-
https://sourceforge.net/projects/redshiftgui/
(I
have to use something like this. Where I used to work, years ago, we were processing a very abrasive mineral, like sharp sand. It was a lot finer, though.....and air-flow helmets wouldn't entirely keep it out. It would get round the back of your eyeballs and cause scratching to the delicate tissue, leaving you with extremely sore eyes. Even now, years after leaving the place, my eyes are permanently sensitized to bright light.....so something like this for night-time use is, for me, a must-have item.)
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There's a very small, lightweight command-line alternative, called SCT (
Set
Color
Temperature). It's available from Github. You need to compile it yourself, but it really is a piece of cake to do so. If a blockhead like me can do it, then you
know it's got to be easy..!
Download the tarball, and extract. Make sure your development tools are installed, or loaded; I'm afraid I've been using Puppy for so long I can't remember how this is done in the mainstream distros; in Pup we 'load' the 'devx' SFS package. Then 'unload' again when finished.
Open a terminal in the directory where you extracted it to, then enter into the terminal the command string found on line 23 of the 'Read Me' file:-
Code:
cc -std=c99 -O2 -I /usr/X11R6/include -o sct sct.c -L /usr/X11R6/lib -lm -lX11 -lXrandr
.....and within 10 seconds you'll get a compiled binary. Move this into /usr/bin, then you can run it using the following terminal command. Very simply
...for example. 3600 is a 'night-time' value (a warm, red-tinted hue).
...would give you a normal, daylight tint.
...would give you a very blue-white light. And so on.
I've used both of these for a while in Pup, and, so far, any screenshots I've taken at night with either of them don't seem to transfer the reddish hue to whatever I take a piccie of.
There's a short video I put together here, showing the process.....although no sound, I'm afraid. It was a demo I knocked up for another member of the Murga-Linux 'Puppy' Forums.
https://youtu.be/X_a6MKDr8XQ
(It's almost certain to be different in whatever you happen to be running, although the principle remains the same.)
You might find the forum thread helpful, too:-
http://www.murga-linux.com/puppy/viewtopic.php?t=111450
Mike.