RGB values of current terminal color settings?

Question

The colors displayed for different ANSI escape codes are configurable via .Xdefaults or directly on the command line via other ANSI escapes.
Is there any way to dump the current values from a terminal? For example, given the ANSI escape code "\033[31m", I would like to know the current RGB values used to display it.
Obviously this will depend on the terminal (e.g. urxvt can have different settings from xterm), but I'm hoping that there is some obscure tool to do this.

Answer 1

Coincidentally, I recently wrote a script to do exactly this: query all the color values from a terminal emulator and show them in a nice table. I was planning to make a thread for this, but this thread is perfect.  In my opinion, the strategy of querying colors from the terminal itself is superior (when it is supported by the terminal) to mucking around with .Xresources, .Xdefaults, or "xrdb --query", which only work in pretty limited situations. The drawbacks of my approach are: (1) it can be challenging to make the same code work on different terminal emulators, and (2) you have to use it from the terminal you want to query, and not from within a screen or tmux session. (I think there may be partial workarounds for (2), but I haven't implemented them.) I've tested my code on a number of terminals, and the upshot is that xterm and urxvt are supported flawlessly, and VTE-based terminals like gnome-terminal and XFCE's "Terminal" are almost fully supported. (I wasn't able to query the default foreground and background colors, but everything else seems to work.) Most other X terminals don't seem to support this method of querying color values.
Here's an example of what the script produces:
Obviously, that's a heavily formatted table, but I think the code has enough comments that you can take what you need from it. It works under python 3 or python 2.7.
Edit: This version is superseded by the one in post #27, which is structured better. I'm leaving this here since some of the future replies refer to it.
#!/usr/bin/python
This is a Python script to show off your terminal ANSI colors (or more
colors, if your terminal has them). It works on both Python 2.7 and
Python 3.
This script must be run from the terminal whose colors you want to
showcase. Not all terminal types are supported (see below). At the
very minimum, 16-color support is required.
Fully supported terminals:
xterm
urxvt
For these terminals, this script can show a color table with correct RGB
values for each color. It queries the RGB values from the terminal
itself, so it works even if you change the colors after starting the
terminal.
Mostly supported terminals: pretty much all VTE-based terminals. This
includes:
vte
Terminal (XFCE)
gnome-terminal
terminator
tilda
and many more. These are on "mostly" status because I don't know how to
query their foreground and background colors. Everything else works,
though, albeit with noticeable slowness (which may be beyond this
script's control).
Somewhat supported terminals: pretty much all other X-client terminals
I've tried. These include:
konsole (KDE)
terminology (Enlightenment)
Eterm (Enlightenment)
(etc.)
For these terminals, the script can output a color table just fine, but
without RGB values.
Unsupported terminals:
ajaxterm
Linux virtual console (i.e., basic TTY without X-windows)
Warning: do not run this script on the Linux virtual console unless you
want a garbled TTY! That said, you can still type `tput reset<Enter>'
afterward to get back to a usable console. :-) The situation with
ajaxterm is similar, but not as bad.
If a terminal isn't mentioned here, I probably haven't tried it. Attempt
at your own risk!
Note regarding screen/tmux: this script can theoretically be run from a
screen or tmux session, but you will not get any RGB values in the
output (indeed, a screen session can be opened on multiple terminals
simultaneously, so there typically isn't a well defined color value for
a given index). However, it's interesting to observe that screen and
tmux emulate a 256 color terminal independently of the terminal(s)
to which they are attached, which is very apparent if you run the script
with 256-color output on a screen session attached to a terminal with 8-
or 16-color terminfo (or with $TERM set to such).
This code is licensed under the terms of the GNU General Public License:
http://www.gnu.org/licenses/gpl-3.0.html
and with absolutely no warranty. All use is strictly at your own risk.
from sys import stdin, stdout, stderr
import re
import select
import termios
from collections import defaultdict
from argparse import (ArgumentParser, ArgumentError)
# Operating system command
osc = "\033]"
# String terminator
# ("\033\\" is another option, but "\007" seems to be understood by
# more terminals. Terminology, for example, doesn't seem to like
# "\033\\".)
st = "\007"
# Control sequence introducer
csi = "\033["
# ANSI SGR0
reset = csi + 'm'
# Errors that may be raised by rgb_query
num_errors = 0
class InvalidResponseError(Exception):
The terminal's response couldn't be parsed.
def __init__(self, q, r):
global num_errors
num_errors += 1
Exception.__init__(self, "Couldn't parse response " + repr(r) +
" to query " + repr(q))
class NoResponseError(Exception):
The terminal didn't respond, or we were too impatient.
def __init__(self, q):
global num_errors
num_errors += 1
Exception.__init__(self, "Timeout on query " + repr(q))
# Wrappers for xterm & urxvt operating system controls.
# These codes are all common to xterm and urxvt. Their responses aren't
# always in the same format (xterm generally being more consistent), but
# the regular expression used to parse the responses is general enough
# to work for both.
# Note: none of these functions is remotely thread-safe.
def get_fg(timeout):
Get the terminal's foreground (text) color as a 6-digit
hexadecimal string.
return rgb_query([10], timeout)
def get_bg(timeout):
Get the terminal's background color as a 6-digit hexadecimal
string.
return rgb_query([11], timeout)
def get_color(a, timeout):
Get color a as a 6-digit hexadecimal string.
return rgb_query([4, a], timeout)
def test_fg(timeout):
Return True if the terminal responds to the "get foreground" query
within the time limit and False otherwise.
return test_rgb_query([10], timeout)
def test_bg(timeout):
Return True if the terminal responds to the "get background" query
within the time limit and False otherwise.
return test_rgb_query([11], timeout)
def test_color(timeout):
Return True if the terminal responds to the "get color 0" query
within the time limit and False otherwise.
return test_rgb_query([4, 0], timeout)
def test_rgb_query(q, timeout):
Determine if the terminal supports query q.
Arguments: `q' and `timeout' have the same interpretation as in
rgb_query().
Return: True if the terminal gives a valid response within the
time limit and False otherwise.
This function will not raise InvalidResponseError or
NoResponseError, but any other errors raised by rgb_query will
be propagated.
try:
rgb_query(q, timeout)
return True
except (InvalidResponseError, NoResponseError):
return False
# String to use for color values that couldn't be determined
rgb_placeholder = '??????'
# This is what we expect the terminal's response to a query for a color
# to look like. If we didn't care about urxvt, we could get away with a
# simpler implementation here, since xterm and vte seem to give pretty
# consistent and systematic responses. But I actually use urxvt most of
# the time, so....
ndec = "[0-9]+"
nhex = "[0-9a-fA-F]+"
crgb = ("\033\\]({ndec};)+rgba?:" +
"({nhex})/({nhex})/({nhex})(/({nhex}))?").format(**vars())
re_response = re.compile(crgb)
# The problem I'm attempting to work around with this complicated
# implementation is that if you supply a terminal with a query that it
# does not recognize or does not have a good response to, it will simply
# not respond *at all* rather than signaling the error in any way.
# Moreover, there is a large variation in how long terminals take to
# respond to valid queries, so it's difficult to know whether the
# terminal has decided not to respond at all or it needs more time.
# This is why rgb_query has a user-settable timeout.
P = select.poll()
P.register(stdin.fileno(), select.POLLIN)
def flush_input():
Discard any input that can be read at this moment.
repeat = True
while repeat:
evs = P.poll(0)
if len(evs) > 0:
stdin.read()
repeat = True
else:
repeat = False
def rgb_query(q, timeout=-1):
Query a color-valued terminal parameter.
Arguments:
q: The query code as a sequence of nonnegative integers, i.e.,
[q0, q1, ...] if the escape sequence in pseudo-Python is
"\033]{q0};{q1};...;?\007"
timeout: how long to wait for a response. (negative means
wait indefinitely if necessary)
Return: the color value as a 6-digit hexadecimal string.
Errors:
NoResponseError will be raised if the query times out.
InvalidResponseError will be raised if the terminal's
response can't be parsed.
See
http://invisible-island.net/xterm/ctlseqs/ctlseqs.html
("Operating System Controls") to see the various queries
supported by xterm. Urxvt supports some, but not all, of them,
and has a number of its own (see man -s7 urxvt).
Warning: before calling this function, make sure the terminal is
in noncanonical, non-blocking mode.
query = osc + ';'.join([str(k) for k in q]) + ';?' + st
flush_input()
stdout.write(query)
stdout.flush()
# This is addmittedly flawed, since it assumes the entire response
# will appear in one shot. It seems to work in practice, though.
evs = P.poll(timeout)
if len(evs) == 0:
raise NoResponseError(query)
r = stdin.read()
m = re_response.search(r)
if not m:
raise InvalidResponseError(query, r)
# (possibly overkill, since I've never seen anything but 4-digit RGB
# components in responses from terminals, in which case `nd' is 4
# and `u' is 0xffff, and the following can be simplified as well
# (and parse_component can be eliminated))
nd = len(m.group(2))
u = int('f'*nd, 16)
# An "rgba"-type reply (for urxvt) is apparently actually
# rgba:{alpha}/{alpha * red}/{alpha * green}/{alpha * blue}
# I opt to extract the actual RGB values by eliminating alpha. (In
# other words, the alpha value is discarded completely in the
# reported color value, which is a compromise I make in order to get
# an intuitive and compact output.)
if m.group(5):
# There is an alpha component
alpha = float(int(m.group(2), 16))/u
idx = [3, 4, 6]
else:
# There is no alpha component
alpha = 1.0
idx = [2, 3, 4]
c_fmt = '%0' + ('%d' % nd) + 'x'
components = [int(m.group(i), 16) for i in idx]
t = tuple(parse_component(c_fmt % (c/alpha)) for c in components)
return "%02X%02X%02X" % t
def parse_component(s):
Take a string representation of a hexadecimal integer and transorm
the two most significant digits into an actual integer (or double
the string if it has only one character).
n = len(s)
if n == 1:
s += s
elif n > 2:
s = s[:2]
return int(s, 16)
def test_num_colors(timeout):
Attempt to determine the number of colors we are able to query from
the terminal. timeout is measured in milliseconds and has the same
interpretation as in rgb_query. A larger timeout is safer but will
cause this function to take proportionally more time.
if not test_color(timeout):
return 0
a = 0
b = 1
while test_rgb_query([4, b], timeout):
a = b
b += b
while b - a > 1:
c = (a + b)>>1
if test_rgb_query([4, c], timeout):
a = c
else:
b = c
return b
class ColorDisplay(object):
Class for producing a colored display of terminal RGB values.
def __init__(self, timeout=100, color_level=3, do_query=True):
timeout: same interpretation as in rgb_query. A larger timeout
will be used a small number of times to test the
capabilities of the terminal.
color_level: how much color should be in the output. Use 0 to
suppress all color and 3 or greater for maximum coloredness.
do_query: whether to attempt to query RGB values from the
terminal or just use placeholders everywhere
self.timeout=timeout
self.color_level=color_level
# try getting the rgb value for color 0 to decide whether to
# bother trying to query any more colors.
self.do_query = do_query and test_color(self.timeout*5)
def none_factory():
return None
# colors for highlighting
self.hi = defaultdict(none_factory)
self.hi['['] = 10
self.hi[']'] = 10
self.hi['+'] = 9
self.hi['/'] = 9
for c in '0123456789ABCDEF':
self.hi[c] = 12
def show_ansi(self):
Show the 16 ANSI colors (colors 0-15).
color_order = [0, 1, 3, 2, 6, 4, 5, 7]
names = [' Black ', ' Red ', ' Green ', ' Yellow ',
' Blue ', ' Magenta', ' Cyan ', ' White ']
stdout.write(self.fgcolor('15', 3))
for k in range(8):
a = color_order[k]
stdout.write(names[a])
stdout.write('\n')
stdout.write(self.fgcolor(None, 3))
c = None
for k in range(8):
a = color_order[k]
c = self.hiprint(' [%X/%X] ' % (a, 8 + a), c)
stdout.write('\n')
self.show_color_table([0,8], color_order)
def show_color_cube(self, n):
Show the "RGB cube" (xterm colors 16-231 (256-color) or 16-79
(88-color)). The cube has sides of length 6 or 4 (for 256-color
or 88-color, respectively).
base = {256:6, 88:4}[n]
c = None
c = self.hiprint('[ + ] ', c)
for w in range(base):
c = self.hiprint('[%X] ' % w, c)
stdout.write('\n\n' + self.fgcolor(None, 3))
for u in range(base):
for v in range(base):
stdout.write(' '*v)
x = (u*base + v)*base
self.hiprint(' [%02X] ' % (16 + x))
for w in range(base):
self.show_color(x + w + 16)
stdout.write('\n')
stdout.write('\n\n')
def show_grayscale_ramp(self, end):
Show the "grayscale ramp" (xterm colors 232-255 (256-color) or
80-87 (88-color)).
start = {256:232, 88:80}[end]
n = end - start
vals = [self.get_color(a) for a in range(start, end)]
#stdout.write(reset)
c = None
c = self.hiprint('[ ', c)
for v in range(n):
c = self.hiprint('%02X ' % (start + v), c)
c = self.hiprint(']\n', c)
stdout.write('\n ' + self.fgcolor(None, 3))
for v in range(n):
stdout.write(' ' + self.block(start + v, 2))
stdout.write('\n ')
for u in range(3):
for v in range(n):
stdout.write(' ')
stdout.write(self.fgcolor(start + v, 2))
stdout.write(vals[v][2*u : 2*(u + 1)])
stdout.write(self.fgcolor(None, 2))
stdout.write('\n ')
stdout.write('\n')
def show_colors(self, n):
Make a table showing colors 0 through n-1.
self.show_color_table(range(0,n,8), range(8), n, True)
def show_color_table(self, rows, cols, stop=-1, label=False):
Make a color table with all possible color indices of the form
rows[k] + cols[j] that are less than `stop' (if `stop' is not
negative). If label is True, then print row and column labels.
if label:
self.hiprint('[ + ]')
stdout.write(self.fgcolor(None, 3))
for a in cols:
stdout.write(' ' + self.octal(a) + ' ')
stdout.write('\n')
if label:
stdout.write(' ')
stdout.write('\n')
for b in rows:
if label:
stdout.write(self.octal(b) + ' ')
for a in cols:
c = a + b
if stop < 0 or c < stop:
self.show_color(b + a)
else:
stdout.write(' ')
stdout.write('\n')
stdout.write('\n')
def show_color(self, a):
Make a pretty display of color number `a', showing a block of
that color followed by the 6-character hexadecimal code for the
color.
stdout.write(' ' + self.block(a) + ' ')
stdout.write(self.fgcolor(a, 2) + (self.get_color(a)))
stdout.write(self.fgcolor(None, 2))
def hiprint(self, s, last_color=-1):
Print s to stdout, highlighting digits, brackets, etc. if the
color level allows it.
Arguments:
s: the string to print.
last_color: the current terminal foreground color. This
should be `None' if no color is set, or the current
color index, or something else (like a negative integer)
if the color isn't known. (The last option is always
safe and will force this function to do the right
thing.)
Return: the current foreground color, which can be passed as
last_color to the next call if the color isn't changed in
between.
for c in s:
if c == ' ':
color = last_color
else:
color = self.hi[c]
if color != last_color:
stdout.write(self.fgcolor(color, 3))
stdout.write(c)
last_color = color
return last_color
def octal(self, x):
Return a base-8 string for the integer x, highlighted if the
color level allows it.
return self.fgcolor(self.hi['+'], 3) + '0' + \
self.fgcolor(self.hi['0'], 3) + ('%03o' % x)
def block(self, c, n=1):
Return a string that prints as a block of color `c' and size `n'.
return self.bgcolor(c, 1) + ' '*n + self.bgcolor(None, 1)
# Changing the foreground and background colors.
# While the 38;5 and 48;5 SGR codes are less portable than the usual
# 30-37 and 40-47, these codes seem to be fairly widely implemented (on
# X-windows terminals, screen, and tmux) and support the whole color
# range, as opposed to just colors 0-8. They also make it very easy to
# set the background to a given color without needing to mess around
# with bold or reverse video (which are hardly portable themselves).
# This is useful even for the 16 ANSI colors.
def fgcolor(self, a=None, level=-1):
Return a string designed to set the foreground color to `a' when
printed to the terminal. None means default.
if self.color_level >= level:
if a is None:
return csi + '39m'
else:
return csi + '38;5;' + str(a) + 'm'
else:
return ''
def bgcolor(self, a=None, level=-1):
Return a string designed to set the background color to `a' when
printed to the terminal. None means default.
if self.color_level >= level:
if a is None:
return csi + '49m'
else:
return csi + '48;5;' + str(a) + 'm'
else:
return ''
def get_color(self, a):
if self.do_query:
try:
return get_color(a, timeout=self.timeout)
except (InvalidResponseError, NoResponseError):
return rgb_placeholder
else:
return rgb_placeholder
# Command-line arguments
timeout_dft = 200
parser = ArgumentParser(
description="Python script to show off terminal colors.",
epilog="Run this script from the terminal whose colors " +
"you want to showcase. " +
"For a brief synopsis of which terminal types are " +
"supported, see the top of the source code.")
mode_group = parser.add_mutually_exclusive_group()
p_choices = [16, 88, 256]
arg_p = mode_group.add_argument(
'-p', '--pretty',
action='store_true', default=False,
help="show colors 0 through N-1 in a pretty format. " +
("N must belong to %r. " % p_choices) +
"If N > 16, it should be the actual number of colors " +
"supported by the terminal, or the output will almost " +
"certainly not be pretty.")
mode_group.add_argument(
'-f', '--flat',
action='store_true', default=False,
help="show a simple table with colors 0 through N-1. ")
parser.add_argument(
'n', nargs='?', metavar='N',
type=int, default=16,
help="number of colors to show. " +
"Unless you explicitly supply -p/--pretty or -f/--flat, " +
"--pretty is used if possible and --flat is used " +
"otherwise. " +
"N defaults to 16, showing the ANSI colors 0-15. " +
"If N is 0, the script will attempt to determine the " +
"maximum number of colors automatically " +
"(which may be slow).")
parser.add_argument(
'--no-fgbg',
action='store_false', dest='fgbg', default=True,
help="suppress display of foreground/background colors.")
parser.add_argument(
'--no-query',
action='store_false', dest='do_query', default=True,
help="don't try to query any RGB values from the terminal " +
"and just use placeholders.")
parser.add_argument(
'-t', '--timeout', metavar='T',
type=int, default=timeout_dft,
help="how long to wait for the terminal to "
"respond to a query, in milliseconds " +
"[default: {0}]. ".format(timeout_dft) +
"If your output has '?' characters " +
"instead of RGB values " +
"or junk printed after the script runs, " +
"increasing this value may or may not " +
"help, depending on the terminal. " +
"A negative T will behave like infinity.")
parser.add_argument(
'-l', '--level', metavar='L',
type=int, default=3,
help="choose how much color to use in the output. " +
"(0 = no color; 3 = most color [default])")
if __name__ == '__main__':
args = parser.parse_args()
assert not (args.pretty and args.flat)
if args.pretty:
if args.n not in p_choices:
raise ArgumentError(
arg_p,
"N must belong to %r" % p_choices)
tc_save = None
try:
tc_save = termios.tcgetattr(stdout.fileno())
tc = termios.tcgetattr(stdout.fileno())
# Don't echo the terminal's responses
tc[3] &= ~termios.ECHO
# Noncanonical mode (i.e., disable buffering on the terminal
# level)
tc[3] &= ~termios.ICANON
# Make input non-blocking
tc[6][termios.VMIN] = 0
tc[6][termios.VTIME] = 0
termios.tcsetattr(stdout.fileno(), termios.TCSANOW, tc)
if args.n == 0:
args.n = test_num_colors(args.timeout)
# We are guaranteed to have failed some queries now, but
# that isn't meaningful.
num_errors = 0
if not (args.pretty or args.flat):
if args.n in p_choices:
args.pretty = True
else:
args.flat = True
if args.level >= 1:
stdout.write(reset)
if args.fgbg:
if args.do_query:
try:
bg = get_bg(timeout=args.timeout)
except (InvalidResponseError, NoResponseError):
bg = rgb_placeholder
try:
fg = get_fg(timeout=args.timeout)
except (InvalidResponseError, NoResponseError):
fg = rgb_placeholder
else:
bg = rgb_placeholder
fg = rgb_placeholder
stdout.write("\n Background: %s\n" % bg)
stdout.write(" Foreground: %s\n\n" % fg)
C = ColorDisplay(args.timeout, args.level, args.do_query)
if args.pretty:
assert args.n in p_choices
stdout.write('\n ANSI colors:\n\n')
C.show_ansi()
if args.n > 16:
stdout.write('\n RGB cube:\n\n')
C.show_color_cube(args.n)
stdout.write(' Grayscale ramp:\n\n')
C.show_grayscale_ramp(args.n)
else:
C.show_colors(args.n)
if num_errors > 0:
stderr.write("Warning: not all queries succeeded\n" +
"Warning: (output contains " +
"placeholders and may be inaccurate)\n")
finally:
if args.level >= 1:
stdout.write(reset)
flush_input()
if tc_save != None:
termios.tcsetattr(stdout.fileno(),
termios.TCSANOW, tc_save)
Run it as
python showcolors.py -h
to get an overview of the functionality.
TL;DR: you can echo a string like "\033]4;13;?\007" to an xterm, and it will output the RGB value of color #13 to itself in the form "\033]4;13;rgb:rrrr/gggg/bbbb\007", which you can then read and parse. To try it out:
$ echo -en "\033]4;13;?\007"
There are some subtleties if you want this to work on other terminals like urxvt; for that you can experiment yourself or read the code. 
Further reading: http://invisible-island.net/xterm/ctlseqs/ctlseqs.html (heading "Operating System Controls").
Xyne, regarding determining the number of colors: I don't know how to do that completely reliably. You can try simply
tput colors
but this relies on the value of $TERM and its terminfo and thus may be unreliable. A kludgy but workable way to do this using the "rgb_query" function in my script is to query color values using binary search to find the highest color value the terminal will allow you to query. The main problem with this is that if you query an invalid color index, then the terminal just won't respond at all, and if you query a valid index, it will respond but after a somewhat unpredictable delay, so it's hard to know for sure which one is the case. Like I said, it's kludgy but workable.
Edit: I went ahead and added that functionality to my script. Try running it as
python showcolors.py 0
or look at the function "test_num_colors".
Last edited by Lux Perpetua (2012-10-22 11:18:21)