l0b0 / xterm-color-count

Count how many colors your XTerm actually supports

XTerm Color Count

Count how many colors your XTerm actually supports, since it may be different from what tput colors reports.

For example, both gnome-terminal and XTerm support 256 colors, but tput colors returns 8.

Usage

./xterm-color-count.sh

You might have to wait a few seconds for the result to be returned.

./xterm-color-count.sh -v

Print each color number and show what it looks like.

./xterm-color-count.sh [number]

Show all the colors, like -v, but use a given number instead of the count.

Bugs

• This does not work with the Linux console as it does not support the OSC 4 escape sequence. Instead the script falls back to tput colors which uses the terminfo file.

Discussion

• It is a mystery why the default terminfo for XTerm and gnome-terminal lie about how many colors they have. You can "fix" it so tput colors returns the proper result by using export TERM=xterm-256color. Some applications (such as emacs in a terminal window) will use the extra colors. For example, try,

    TERM=xterm-256color  emacs -nw -f list-colors-display -f delete-window
  

• A 256 color XTerm has this color mapping

  • System colors: 0 to 15
  • Grayscale: 232 to 255 (note, black and white intentionally omitted)
  • 6x6x6 color cube: 16-231 (For R,G,B between 0 and 5, color-index = 16 + R×6×6 + G×6 + B)

Credit

L0b0 wrote the code, hackerb9 changed it to a binary search. Gilles did all the research, and has awesome communication skills and *nix knowledge.