PHP: Automatically disabling colored output

php-sqllint got an SQL formatting output mode now. Together with SqlParser's output coloring mode (which generates ANSI escape codes) I get nice colorful SQL statements on my terminal. ​

But this is not what I want when piping the output to another tool that does not understand escape sequences. ​

Using a --color option is too inconvenient for day-to-day use, and using --nocolor for piping is also not convenient. It should just work. ​

PHP's POSIX extension offers a posix_isatty() function that can be used to check if the output devices is an interactive TTY or not: ​

$usecolors = true;
if (function_exists('posix_isatty')
    && !posix_isatty(STDOUT)
) {
    $usecolors = false;
}

This code automatically enables coloring except when the output is not a teletype (non-interactive). Coloring can then be done with e.g. Console_Color2. ​

Other implementations​

Symfony's Console's StreamOutput class uses posix_isatty for unix systems, and uses environment variables on Windows to detect if the terminal has been made ANSI-capable: ​

protected function hasColorSupport()
{
    if (DIRECTORY_SEPARATOR === '\\') {
        return false !== getenv('ANSICON')
            || 'ON' === getenv('ConEmuANSI')
            || 'xterm' === getenv('TERM');
    }
 
    return function_exists('posix_isatty') && @posix_isatty($this->stream);
}