NAME
	radharc - Adjust display colour temperature after the Sun

SYNOPSIS
	radharc [-M method] [-S site] [-c crtc] ... [-R rule] [-p priority] [-f fade-in]
	        [-F fade-out] [-h [high-temp][@high-elev]] [-l [low-temp][@low-elev]]
	        [-W options] ... (-L latitude:longitude | -t temperature [-d] | -x)

DESCRIPTION
	radharc adjusts the colour temperature of your monitor according
	the the elevation of the Sun. This is intended to reduce eye strain
	and reduce deplayed sleep phase syndrome.

	radharc is inspired by redshift(1) but uses libcoopgamma(7) to allow it
	to be used alongside other programs that also modify the monitors
	colour output, as long as the also use libcoopgamma(7).

OPTIONS
	The following options are supported:

	-c crtc
		Apply the filter to the CRTC with the monitor whose EDID is crtc.
		By default, the filter is applied to all monitors.

		If crtc is '?', all available CRTC's are listed.

	-d
		Keep the process alive and remove the filter on death.

	-f fade-in
		Set effect fade-in time (gradual application when the program
		starts). The value is interpreted a real number of seconds.

	-F fade-out
		Set effect fade-out time (gradual restoration when the program
		stops). The value is interpreted a real number of seconds.

	-h [high-temp][@high-evel]
		Selects that the colour temperature shall be high-temp Kelvins
		when the Sun's elevation is high-evel degrees or higher above
		the horizon.

		This option only has effect when combined with the -L option.

	-l [low-temp][@low-evel]
		Selects that the colour temperature shall be low-temp Kelvins
		when the Sun's elevation is low-evel degrees or lower above
		the horizon.

		This option only has effect when combined with the -L option.

	-L latitude:longitude
		Selects the location the Sun's elevation shall be calculated
		for. The program will run until it is manually terminated and
		continually readjust the colour temperature according the
		the Sun's elevation. The latitude and longitude shall be
		specified in decimal format. Positive numbers shall be used
		GPS coordinates north of the equator and GPS coordinates
		east of the prime meridian. Negative number shall be used
		for GPS coordinates south of the equator and GPS coordinates
		west of the prime meridian.

	-M method
		Adjustment method name or number. Recognised names include:
		dummy     Dummy method
		randr     X RAndR
		vidmode   X VidMode
		drm       Linux DRM
		gdi       Windows GDI
		quartz    Quartz Core Graphics

		The adjustment methods are supported via libgamma(7). Only methods
		that were enabled when libgamma was compiled will be supported.

		If method is '?', all available adjustment methods are printed.

	-p priority
		Set the priority of the filter. Filters with higher priority
		are applied before filters with lower priority. The value must
		be a signed 64-bit integer (between -9223372036854775807 and
		9223372036854775807). radharc's default priority is
		-2305843009213693952.

		If priority is '?', the utility's default priority is printed.

	-R rule
		Set the rule of the filter to rule. This is the last part of
		the filter's identifier (class). The default rule is standard.

	-S site
		Select the site to which to connect. For example ':0', for local
		display 0 when using X.

	-t temperature
		Colour temperature, in Kelvins, to apply.

		If temperature is '?' or 'get', the utility will print the
		currently applied temperature.

	-W options
		Comma-separated list of implementation-specific options.

		Supported options are:

		linear=value
			If value is 'yes', the effect will be surrounded
			by an effect equivalent to that of cg-linear(1),
			the two effects will be applied as one.

			If value is 'no', the above will not be done.

		socket=name
			Select name (abstract address) of the socket created
			for IPC functionality.

			if name is '-', the standard input will be used, and
			must be a bound unix(7) datagram socket.

			If no specified, and no-socket has not been
			specified, a default string will be used, being
			defined by the pattern

				"/proc/%u/%s", <PID>, <class>

			Any comma (,) will be interpeted as part of name.

		no-socket
			Do not create a socket for IPC functionality.

	-x
		Remove the currently applied filter.

OPERANDS
	No operands are supported.

SIGNALS
	The following signals have non-default meaning:

	SIGINT
		Gradually fade out the effect and terminate the process.

		If the fade out time is 0 (default) or if the signal is sent
		twice, the effect is removed immediately.

	SIGHUP
		Terminate the process after any current fade in or fade out
		action, but leaf the effect in place.

	SIGUSR1
		Gradually fade out the effect but do not terminate the process.

		If the fade out time is 0 (default) or if the signal is sent
		twice, the effect is removed immediately.

	SIGUSR2
		Gradually fade the effect back in (from SIGUSR1).

		If the fade in time is 0 (default) or if the signal is sent
		twice, the effect is restored immediately.

		If sent during the initial fade in, the fade in is cancelled
		and the full effect is immediately applied.

SEE ALSO
	radharc-ipc(1), coopgammad(1), cg-tools(7), redshift(1), blueshift(1)