what are the differences between PHP base64_encode and *nix base64

Question

PHP's base64_encode is returning a different string to the linux base64 command. Why is this?

PHP:

$ php
<?php
echo base64_encode('test');
?>
dGVzdA==

Linux base64:

$ echo 'test' | base64
dGVzdAo=

Answer 1

echo usually outputs a new line character at the end of the string, to suppress that use the -n switch:

$ echo -n 'test' | base64
dGVzdA==

Or even better, use the portable printf:

$ printf 'test' | base64
dGVzdA==

Similarly for PHP:

$ php <<PHP
<?php echo base64_encode("test\n"); ?>
PHP
dGVzdAo=