Last updated: 2023-05-06

An increasing number of command-line software programs output text with
ANSI color
escape codes by default.
While some developers and users obviously prefer seeing these colors,
some users don’t.
Unfortunately, every new piece of software seems to have a
different way
of disabling colored text output and some software has no way at all.

Accepting the futility of trying to reverse this trend in 2017, an informal
standard was proposed:

Command-line software which adds ANSI color to its output by default should
check for a NO_COLOR environment variable that, when present and not an empty
string (regardless of its value), prevents the addition of ANSI color.

By adopting this standard, users that prefer to have plain, non-colored text
output can export NO_COLOR=1 to their shell’s environment and automatically
disable color by default in all supported software.

If your software outputs color by default, please consider not doing so.
If you insist, please implement this standard to make it easy for your
users to disable color and then add your software to this list by
submitting a pull request.

If your software does not output color by default, you do not need to bother
with this standard.

Example Implementation

#include 
#include 
#include 

int
main(int argc, char *argv[])
{
	char *no_color = getenv("NO_COLOR");
	bool color = true;

	if (no_color != NULL && no_color[0] != '')
		color = false;

	/* do getopt(3) and/or config-file parsing to possibly turn color back on */
	...
}

Frequently Asked Questions

1. Why not just set $TERM to dumb or xterm without color support?
   Or change all color definitions in the terminal to print the same color?

   The terminal is capable of color and should be able to print color when
   instructed.
   NO_COLOR is a hint to the software running in the terminal to suppress
   addition of color, not to the terminal to prevent any color from being
   shown.

   It is reasonable to configure certain software such as a text editor to use
   color or other ANSI attributes sparingly (such as the reverse attribute for
   a status bar) while still desiring that other software not add color unless
   configured to.
   It should be up to the user whether color is used, not the software author.

2. How should configuration files and command-line arguments be processed
   in the presence of $NO_COLOR?

   User-level configuration files and per-instance command-line arguments
   should override $NO_COLOR.
   A user should be able to export $NO_COLOR in their shell configuration
   file as a default, but configure a specific program in its configuration
   file to specifically enable color.

   This also means that software that can add color but doesn’t by default
   does not need to care about $NO_COLOR, because it will only ever be
   adding color when instructed to do so (as it should be).

Color libraries supporting NO_COLOR to disable default color output

Software using these libraries to output color inherently support disabling
color by default via NO_COLOR.

Software directly supporting NO_COLOR to disable color output by default