Standard for ANSI Colors in Terminals

The current situation to get colored output from most console commands is a mess. Some check for the TERM environment variable, or look for ANSICON on Windows, or need to be passed a parameter like --color, --ansi or -fdiagnostics-color.

That’s why this page tries to create some sort of “standard” which programs should comply to no matter on which platform they are run.

The idea is to have the environment variables CLICOLOR and CLICOLOR_FORCE (which are currently already used for this exact reason on some UNIX systems). When set, the following rules should apply:

CLICOLOR != 0
- ANSI colors are supported and should be used when the program isn’t piped.
CLICOLOR == 0
- Don’t output ANSI color escape codes.
CLICOLOR_FORCE != 0
- ANSI colors should be enabled no matter what.

If you have ideas or comments please create a new issue on GitHub or edit this page.

How to Implement

If you want to check in your program if ANSI colors are supported, it should look like this Python code example:

import os, sys

def has_colors():
    if ((os.getenv("CLICOLOR", "1") != "0" and sys.stdout.isatty()) or
        os.getenv("CLICOLOR_FORCE", "0") != "0"):
        return True
    else:
        return False

Supported Colors

To get an idea what colors you can use, run the following Python script:

RESET = "\x1b[0m"
print("To reset attributes: \\x1b[0m\n")
for i in range(0, 8):
    print("\x1b[1;3{0}m\\x1b[1;3{0}m{1} \x1b[0;3{0}m\\x1b[0;3{0}m{1} "
          "\x1b[1;4{0};3{0}m\\x1b[1;3{0};4{0}m{1}".format(i, RESET))

Which should print:

To reset attributes: \x1b[0m

\x1b[1;30m \x1b[0;30m \x1b[1;30;40m
\x1b[1;31m \x1b[0;31m \x1b[1;31;41m
\x1b[1;32m \x1b[0;32m \x1b[1;32;42m
\x1b[1;33m \x1b[0;33m \x1b[1;33;43m
\x1b[1;34m \x1b[0;34m \x1b[1;34;44m
\x1b[1;35m \x1b[0;35m \x1b[1;35;45m
\x1b[1;36m \x1b[0;36m \x1b[1;36;46m
\x1b[1;37m \x1b[0;37m \x1b[1;37;47m

Also see the ISO 6429 (ANSI) color sequences.

Windows

Windows 10 supports ANSI colors since v1511. For earlier versions of Windows installing ANSICON will enable ANSI colors in cmd.exe.

Bug Reports

This is a list of bug reports on the progress of supporting CLICOLOR:

The following bug reports have been resolved: