|Description:||Determines the MIME type of a file by looking at a few bytes of its contents|
This module determines the MIME type of files in the same way the Unix
file(1) command works: it looks at the first few bytes of the file. It is intended as a "second line of defense" for cases that
mod_mime can't resolve.
This module is derived from a free version of the
file(1) command for Unix, which uses "magic numbers" and other hints from a file's contents to figure out what the contents are. This module is active only if the magic file is specified by the
The contents of the file are plain ASCII text in 4-5 columns. Blank lines are allowed but ignored. Commented lines use a hash mark (
#). The remaining lines are parsed for the following columns:
|1||byte number to begin checking from
type of data to match
|3||contents of data to match|
|4||MIME type if matched|
|5||MIME encoding if matched (optional)|
For example, the following magic file lines would recognize some audio formats:
# Sun/NeXT audio data 0 string .snd >12 belong 1 audio/basic >12 belong 2 audio/basic >12 belong 3 audio/basic >12 belong 4 audio/basic >12 belong 5 audio/basic >12 belong 6 audio/basic >12 belong 7 audio/basic >12 belong 23 audio/x-adpcm
Or these would recognize the difference between
*.doc files containing Microsoft Word or FrameMaker documents. (These are incompatible file formats which use the same file suffix.)
# Frame 0 string \<MakerFile application/x-frame 0 string \<MIFFile application/x-frame 0 string \<MakerDictionary application/x-frame 0 string \<MakerScreenFon application/x-frame 0 string \<MML application/x-frame 0 string \<Book application/x-frame 0 string \<Maker application/x-frame # MS-Word 0 string \376\067\0\043 application/msword 0 string \320\317\021\340\241\261 application/msword 0 string \333\245-\0\0\0 application/msword
An optional MIME encoding can be included as a fifth column. For example, this can recognize gzipped files and set the encoding for them.
# gzip (GNU zip, not to be confused with # [Info-ZIP/PKWARE] zip archiver) 0 string \037\213 application/octet-stream x-gzip
This module is not for every system. If your system is barely keeping up with its load or if you're performing a web server benchmark, you may not want to enable this because the processing is not free.
However, an effort was made to improve the performance of the original
file(1) code to make it fit in a busy web server. It was designed for a server where there are thousands of users who publish their own documents. This is probably very common on intranets. Many times, it's helpful if the server can make more intelligent decisions about a file's contents than the file name allows ...even if just to reduce the "why doesn't my page work" calls when users improperly name their own files. You have to decide if the extra work suits your environment.
The following notes apply to the
mod_mime_magic module and are included here for compliance with contributors' copyright restrictions that require their acknowledgment.
mod_mime_magic: MIME type lookup via file magic numbers
Copyright (c) 1996-1997 Cisco Systems, Inc.
This software was submitted by Cisco Systems to the Apache Group in July 1997. Future revisions and derivatives of this source code must acknowledge Cisco Systems as the original contributor of this module. All other licensing and usage conditions are those of the Apache Group.
Some of this code is derived from the free version of the file command originally posted to comp.sources.unix. Copyright info for that program is included below as required.
- Copyright (c) Ian F. Darwin, 1987. Written by Ian F. Darwin.
This software is not subject to any license of the American Telephone and Telegraph Company or of the Regents of the University of California.
Permission is granted to anyone to use this software for any purpose on any computer system, and to alter it and redistribute it freely, subject to the following restrictions:
For compliance with Mr Darwin's terms: this has been very significantly modified from the free "file" command.
|Description:||Enable MIME-type determination based on file contents using the specified magic file|
|Context:||server config, virtual host|
MimeMagicFile directive can be used to enable this module, the default file is distributed at
conf/magic. Non-rooted paths are relative to the
ServerRoot. Virtual hosts will use the same file as the main server unless a more specific setting is used, in which case the more specific setting overrides the main server's file.
© 2017 The Apache Software Foundation
Licensed under the Apache License, Version 2.0.