Quickest Way to Read First Line from File

What's the quickest, easiest way to read the first line only from a file? I know you can use file, but in my case there's no point in wasting the time loading the whole file.

Preferably a one-liner.

Well, you could do:

$f = fopen($file, 'r');
$line = fgets($f);
fclose($f);

It's not one line, but if you made it one line you'd either be screwed for error checking, or be leaving resources open longer than you need them, so I'd say keep the multiple lines

Edit

If you ABSOLUTELY know the file exists, you can use a one-liner:

$line = fgets(fopen($file, 'r'));

The reason is that PHP implements RAII for resources.

That means that when the file handle goes out of scope (which happens immediately after the call to fgets in this case), it will be closed.

$firstline=`head -n1 filename.txt`;

I'm impressed no one mentioned the file() function:

$line = file($filename)[0];

or if version_compare(PHP_VERSION, "5.4.0") < 0:

$line = array_shift(file($filename));