Question

I am trying to determine a file’s mime type. I’ve tried a few methods, but haven’t come up with anything that gives consistent output. I’ve tried $mime = mime_content_type($file) and $mime = exec('file -bi ' . $file). I am serving up images, CSS, and JavaScript.

Example mime_content_type() output:

• jquery.min.js – text/plain
• editor.js – text/plain
• admin.css – text/plain
• controls.css – application/x-troff
• logo.png – text/plain

Example exec(...) output:

• jquery.min.js – text/plain; charset=us-ascii
• editor.js – text/x-c++; charset=us-ascii
• admin.css – text/x-c; charset=us-ascii
• controls.css – text/x-c; charset=us-ascii
• logo.png – image/png

As can be seen here, the results are all over the place.

My PHP version is 5.2.6

---

SOLUTION (thanks to Jacob)

$mimetypes = array(
    'gif' => 'image/gif',
    'png' => 'image/png',
    'jpg' => 'image/jpg',
    'css' => 'text/css',
    'js' => 'text/javascript',
);
$path_parts = pathinfo($file);
if (array_key_exists($path_parts['extension'], $mimetypes)) {
    $mime = $mimetypes[$path_parts['extension']];
} else {
    $mime = 'application/octet-stream';
}

Answer 1

The Fileinfo extension will do the job, if you’re on >= 5.30

• You should try to avoid having to execute commands
• mime_content_type is deprecated in PHP 5.30

---

If unfortunately you are on < 5.30, then I would probably just write it myself, it’s a lot more reliable than what you’re getting from the above functions/commands.

Here’s an example:

<?php
$filename = 'FILENAME HERE';
$mimetypes = array('png' => 'image/png', 'jpg' => 'image/jpg', 'css' => 'text/css',
    'js' => 'application/x-javascript'
    // any other extensions that you may be serving      
);

$ext = strtolower(substr($filename, strrpos($filename, '.') + 1, strlen($filename)));
if(array_key_exists($ext, $mimetypes)) {
    $mime = $mimetypes[$ext];
} else {
    echo 'mime type not found';
}

?>