public static boolean checkHasFile() {
        return checkHasFile(DEFAULT_FILE_COMMAND_PATH);
    }
This runs the linux 'file' command against a file.  If
this is called on a TikaInputStream, it will use the underlying Path
or spool the full file to disk and then run file against that.
<p>
If this is run against any other type of InputStream, it will spool
up to {@link #maxBytes} to disk and then run the detector.
<p>
As with all detectors, mark must be supported.
<p>
If you want to use file's mime type in the parse, e.g.
to select the parser in AutoDetectParser, set {@link FileCommandDetector#setUseMime(boolean)}
to true.  The default behavior is to store the value as {@link FileCommandDetector#FILE_MIME}
but rely on other detectors for the "active" mime used by Tika.
tika-core/src/main/java/org/apache/tika/detect/FileCommandDetector.java