PHP - how to best determine if the current invocation is from CLI or web server?

I have been using this function for a few years

function is_cli()
{
    if ( defined('STDIN') )
    {
        return true;
    }

    if ( php_sapi_name() === 'cli' )
    {
        return true;
    }

    if ( array_key_exists('SHELL', $_ENV) ) {
        return true;
    }

    if ( empty($_SERVER['REMOTE_ADDR']) and !isset($_SERVER['HTTP_USER_AGENT']) and count($_SERVER['argv']) > 0) 
    {
        return true;
    } 

    if ( !array_key_exists('REQUEST_METHOD', $_SERVER) )
    {
        return true;
    }

    return false;
}

php_sapi_name is the function you will want to use as it returns a lowercase string of the interface type. In addition, there is the PHP constant PHP_SAPI.

Documentation can be found here: http://php.net/php_sapi_name

For example, to determine if PHP is being run from the CLI, you could use this function:

function isCommandLineInterface()
{
    return (php_sapi_name() === 'cli');
}

php_sapi_name() is really not the best way to perform this check because it depends on checking against many possible values. The php-cgi binary can be called from the command line, from a shell script or as a cron job and (in most cases) these should also be treated as 'cli' but php_sapi_name() will return different values for these (note that this isn't the case with the plain version of PHP but you want your code to work anywhere, right?). Not to mention that next year there may be new ways to use PHP that we can't possibly know now. I'd rather not think about it when all I care about is weather I should wrap my output in HTML or not.

Fortunately, PHP has a way to check for this specifically. Just use http_response_code() without any parameters and it'll return TRUE if ran from a web server type environment and FALSE if ran from a CLI type environment. Here is the code:

$is_web=http_response_code()!==FALSE;

This will even work if you accidentally(?) set a response code from a script running from the CLI (or something like the CLI) before you call this.

I think he means if PHP CLI is being invoked or if it is a response from a web request. The best way would be to use php_sapi_name() which if it was running a web request would echo Apache if that is what it was running.

To list of a few taken from the php docs on php_sapi_name():

• aolserver
• apache
• apache2filter
• apache2handler
• caudium
• cgi (until PHP 5.3)
• cgi-fcgi
• cli
• cli-server (Built-in web server as of PHP 5.4)
• continuity
• embed
• fpm-fcgi
• isapi
• litespeed
• milter
• nsapi
• phttpd
• pi3web
• roxen
• thttpd
• tux
• webjames