Description:
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According to the manual, the environment variable 'MAGIC' will be used as path to the magic file by default. But it looks like this is not the case. Also the documentation states it will use '/usr/share/misc/magic', but in fact it tries multiple files.

Ubuntu places an empty magic file in /etc, in which you may store custom info. But the magic file of the distro is located in '/usr/share/file/magic'. Even though the distro file is in the MAGIC_MIME_LOCATIONS variable as well, the package prefers to use /etc/magic. This is unfortunate.
It seems like the `file` command is able to use multiple magic files, but it looks like the fileinfo extension can only use 1.

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From the manual (http://www.php.net/finfo-open):

magic_file

    Name of a magic database file, usually something like /path/to/magic.mime. If not specified, MAGIC environment variable is used. If this variable is not set neither, /usr/share/misc/magic is used. .mime and/or .mgc is added if appropriate. 

Reproduce code:
---------------
<?php
    var_dump(getenv('MAGIC'));

    putenv('MAGIC=/usr/share/file/magic');
    $finfo= new finfo(FILEINFO_NONE);
    
    echo $finfo->file(__FILE__);
?>

Expected result:
----------------
bool(false)
PHP script text

Actual result:
--------------
bool(false)

Warning: finfo::finfo() [function.finfo-finfo]: Failed to load magic database at '/etc/magic'. in /home/arnold/projects/jasny/jasny-explorer/webroot/test.php on line 5

Warning: finfo::file() [function.finfo-file]: The invalid fileinfo object. in /home/arnold/projects/jasny/jasny-explorer/webroot/test.php on line 7