Is there a list of ANSI color escape codes somewhere in the standard libraries?

Question

I write a lot of little helper scripts, and often these print coloured text in the terminal. For the simplicity of their packaging and distribution, I often want these little scripts to be without any dependencies.

Hence I'm duplicating data like this a lot in scripts:

ansi_colors = {
    None: '\x1b[0m',  # actually black but whatevs
    'red': '\x1b[31m',
    'green' : '\x1b[32m',
    ...
}

Does this data exist anywhere in the core libraries? I dug around and found that curses has some COLOR_* constants, but they are just integers and it's not obvious how those transform into the ANSI escape codes.

I'm already aware of modules like termcolor , colorama , blessings , so please don't suggest to use those - I want to depend to standard libraries only.

Answer 1

You can check the man page console_codes(4) . What you want is the ECMA-48 Set Graphics Rendition:

The ECMA-48 SGR sequence ESC [ parameters m sets display attributes. Several attributes can be set in the same sequence, separated by semicolons. An empty parameter (between semicolons or string initiator or terminator) is interpreted as a zero.

  param result 0 reset all attributes to their defaults 1 set bold 2 set half-bright (simulated with color on a color display) 4 set underscore (simulated with color on a color display) (the colors used to simulate dim or underline are set using ESC ] ...) 5 set blink 7 set reverse video 10 reset selected mapping, display control flag, and toggle meta flag (ECMA-48 says "primary font"). 11 select null mapping, set display control flag, reset toggle meta flag (ECMA-48 says "first alternate font"). 12 select null mapping, set display control flag, set toggle meta flag (ECMA-48 says "second alternate font"). The toggle meta flag causes the high bit of a byte to be toggled before the mapping table translation is done. 21 set normal intensity (ECMA-48 says "doubly underlined") 22 set normal intensity 24 underline off 25 blink off 27 reverse video off 30 set black foreground 31 set red foreground 32 set green foreground 33 set brown foreground 34 set blue foreground 35 set magenta foreground 36 set cyan foreground 37 set white foreground 38 set underscore on, set default foreground color 39 set underscore off, set default foreground color 40 set black background 41 set red background 42 set green background 43 set brown background 44 set blue background 45 set magenta background 46 set cyan background 47 set white background 49 set default background color 

I don't think they are available as-is in any standard Python module. But if you look carefully, you'll notice that the foreground colors are 30 plus the curses constant, while the background colors are 40 plus the curses constant. So you can write something like this:

import curses
def fcolor(c):
    return '\x1B[{0}m'.format(30 + c)
def bcolor(c):
    return '\x1B[{0}m'.format(40 + c)
def fbcolor(f, b):
    return '\x1B[{0};{1}m'.format(30 + f, 40 + b)

print(fbcolor(curses.COLOR_RED, curses.COLOR_YELLOW) + "hello!")

Answer 2

It depends on what you want. ANSI colors technically refers to the 8-color palette implied by ECMA-48 (ISO-6429) which has named constants in curses. Libraries don't store escape sequences; those are in a database . For an ANSI (sic) terminal, those correspond to escape sequences which set graphic rendition (video attributes such as bold, underline, reverse — and color).

termcap, terminfo and curses use a more general notion where you start with a color number and generate the escape sequence which can produce the corresponding color. Terminals can have no colors, multiple colors (8 for instance, but possibly 16, 88, 256 for xterm and similar terminals). The information telling how to do this is stored in the terminal database as named capabilities . To set the ANSI foreground color, you would use setaf , either using a library call or a command-line application such as tput , eg,

tput setaf 4

for color 4 (blue). Simple applications use the low-level termcap or terminfo interfaces, usually with terminfo databases. While you might be inclined to format your own escape sequences, theses interfaces provide formatting functions that let you avoid knowing how many colors a terminal might support. The terminal database tells your program, using the TERM environment variable to select the actual terminal description. If you have a terminal supporting more than 8 colors, the escape sequence is not formed by adding 30 or 40 to the color number.

Here is an example using the low-level terminfo interface from Python:

import curses

curses.setupterm()
curses.putp(curses.tparm(curses.tigetstr("setaf"), curses.COLOR_RED))
curses.putp(curses.tparm(curses.tigetstr("setab"), curses.COLOR_YELLOW))
curses.putp("hello!")
curses.putp(curses.tigetstr("sgr0"))
curses.putp("\n")

Further reading:

• 15.11. curses — Terminal handling for character-cell displays
• ECMA-48: Control Functions for Coded Character Sets

Answer 3

Rodrigo gave a good answer, although the colors are limited to the 8 first colors for foreground. This is my little contribution to handle 16 foreground colors

def fcolor(c):
    if c>7:
        return '\x1B[1;{0}m'.format(22 + c)
    else:
        return '\x1B[0;{0}m'.format(30 + c)
def bcolor(c):
    return '\x1B[{0}m'.format(40 + c)
def fbcolor(f, b):
    if f>7:
        return '\x1B[1;{0};{1}m'.format(22 + f, 40 + b)
    else:
        return '\x1B[0;{0};{1}m'.format(30 + f, 40 + b)