Often we write some console applications that are run by cron.
In these cases we have to check if the script is executed from the command line or it's a normal HTTP request. If it's a command line call then it doesn't make sense to ask for user and password and redirect to a login screen and other validation checks.

Here is how to check if the current php script was started from the command line.

$sapi_type = php_sapi_name();
if (substr($sapi_type, 0, 3) == 'cli') {
echo "You are using CLI PHP (command line, console)\n";
} else {
echo "You are using something else\n";
}
?>