$re = '/(?P<command>\w{1,})(\s?-\s?(?P<description>.*))?/m';
$str = 'avvisi
calcola - Evaluate one or more algebric expressions
caratteri - Count the characters in a text message (use it in reply)
ciclopi - CiloPi stations status
coop - Get UniCoop Firenze opening hours for Pisa Cisanello shop
doodle - Manage doodle-type surveys
help - Help
language - Change language settings
monitor - Monitor a web page and notify changes
note - Save up to 10 notes, callable via inline query
ping - Check if bot is online
quando - Get the original sending datetime for a message (use it in reply)
reminder - Set a reminder
suggestion - Send a suggestion to help improve the bot
tastiera - Send a keyboard with bot commands
ciaone
ciaone - fdfdf
della - f';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php