Xdebug is the one PHP extension almost everybody installs, and for years the command was pecl install xdebug . The Xdebug install page now says that PECL and its website are deprecated, and it lists pie install xdebug/xdebug as the recommended route. The new command is easy. The part that bites people later is leaving Xdebug switched on where it should not be, because it makes PHP a lot slower. This guide covers both: installing it with PIE, and making sure it only runs where you want it. ...