What makes a phar a phar and not a tar or a zip?
PHP 手册

Phar file stub

A Phar's stub is a simple PHP file. The smallest possible stub follows:

<?php __HALT_COMPILER();

A stub must contain as a minimum, the __HALT_COMPILER(); token at its conclusion. Typically, a stub will contain loader functionality like so:

<?php
Phar
::mapPhar();
include 
'phar://myphar.phar/index.php';
__HALT_COMPILER();

There are no restrictions on the contents of a Phar stub, except for the requirement that it conclude with __HALT_COMPILER();. The closing PHP tag

?>
may be included or omitted, but there can be no more than 1 space between the ; and the close tag
?>
or the phar extension will be unable to process the Phar archive's manifest.

In a tar or zip-based phar archive, the stub is stored in the .phar/stub.php file. The default stub for phar-based Phar archives contains approximately 7k of code to extract the contents of the phar and execute them. See Phar::createDefaultStub() for more detail.

The phar alias is stored in a tar or zip-based phar archive in the .phar/alias.txt file as plain text.


What makes a phar a phar and not a tar or a zip?
PHP 手册