Xterm is configured via X resources. This is how you might configure it for white on black, with a lighter blue than the default (adjust the color as you see fit, obviously):
XTerm.VT100.background: Black
XTerm.VT100.color0: Black
XTerm.VT100.color1: Red
XTerm.VT100.color2: Green
XTerm.VT100.color3: Yellow
XTerm.VT100.color4: CornflowerBlue
XTerm.VT100.color5: Magenta
XTerm.VT100.color6: Cyan
XTerm.VT100.color7: White
XTerm.VT100.colorBD: White
XTerm.VT100.colorBDMode: true
XTerm.VT100.colorUL: Yellow
XTerm.VT100.colorULMode: true
XTerm.VT100.cursorColor: Red
XTerm.VT100.foreground: White
You can use X color names (you can see all the color names with xcolors
or in a file called rgb.txt
which may be somewhere under /etc/X11
, /usr/X11
or /usr/share/X11
or some similar location depending on your system) or #RRGGBB
. colorBD
is the color used for bold; with colorBDMode
set to false
(the default), this setting is ignored and bold text is displayed in a bold font. The same goes for colorUL
, colorULMode
and underline. You can go beyond color8
(up to color255
, or less depending on the xterm version and compile-time configuration). color8
through color15
correspond to 0–7 with bold; colors beyond 16 are rarely used by applications unless you've explicitly configured them.
Put these settings into a file called ~/.Xdefaults
. Most systems load this file automatically when you log in. If yours doesn't, add this command to your X startup script:
xrdb -merge ~/.Xdefaults
To test the appearance of foreground color 42 over background color 17, run this in a shell in that terminal:
printf '\033[38;5;%dm\033[48;5;%dm%s\033[0m\n' 42 17 "Hello, world."
If your xterm is compiled without extended color support, you'll need to use the classical control sequences:
printf '\033[3%dm\033[4%dm%s\033[0m\n' 4 1 "Hello, world."
The foreground and background color must be in the range 0–7 in that case. If your xterm is compiled with 16-color support, replace [3
and [4
by [9
and [10
respectively to select the bright versions (colors 8–15).
The colors
function records the names of colors and similar attributes (bold, underline and so on) in the associative array color
. This array associates names with terminal attribute strings, which are numbers, e.g. 00
↔ normal
, 42
↔ bg-green
, …
echo ${(o)color}
If you want to see how the array is built, look at the source of the function: which colors
or less $^fpath/colors(N)
.
The colors
function only defines names and escape strings (in the associative arrays fg
and bg
) for the 8 standard colors. Your terminal may have more. See this answer for how to explore what colors are available.
Best Answer
What language are you writing your application in?
The normal approach is to check if the output device is a tty, and if it is, check if that type of terminal supports colors.
In
bash
, that would look likeIn C, you have to do a lot more typing, but can achieve the same result using isatty and the functions listed in
man 3 terminfo
.