<
H2><
A NAME="InternalBackRefs">Regex Back-Reference Availability</
A></
H2>
One important thing here has to be remembered: Whenever you
use parenthesis in <
EM>Pattern</
EM> or in one of the <
EM>CondPattern</
EM>
back-reference are internally created which can be used with the
strings <
CODE>$N</
CODE> and <
CODE>%N</
CODE> (see below). And these
are available for creating the strings <
EM>Substitution</
EM> and
<
EM>TestCond</
EM>. Figure 2 shows at which locations the back-references are
transfered to for expansion.
<
TABLE CELLSPACING=0 CELLPADDING=2 BORDER=0>
<
TD BGCOLOR="#CCCCCC"><
IMG ALT="[Needs graphics capability to display]"></
TD>
<
STRONG>Figure 2:</
STRONG> The back-reference flow through a rule
We know, this was a crash course of mod_rewrite's internal processing. But
you will benefit from this knowledge when reading the following documentation
of the available directives.
<
H1><
A NAME="Configuration">Configuration Directives</
A></
H1>
<
H3><
A NAME="RewriteEngine">RewriteEngine</
A></
H3>
><
STRONG>Syntax:</
STRONG></
A>
<
CODE>RewriteEngine</
CODE> {<
CODE>on,off</
CODE>}<
BR>
><
STRONG>Default:</
STRONG></
A>
<
STRONG><
CODE>RewriteEngine off</
CODE></
STRONG><
BR>
><
STRONG>Context:</
STRONG></
A>
server config, virtual host, directory, .htaccess<
BR>
><
STRONG>Override:</
STRONG></
A> FileInfo<
BR>
><
STRONG>Status:</
STRONG></
A> Extension<
BR>
><
STRONG>Compatibility:</
STRONG></
A> Apache 1.2<
BR>
The <
CODE>RewriteEngine</
CODE> directive enables or disables the runtime
rewriting engine. If it is set to <
CODE>off</
CODE> this module does no runtime
processing at all. It does not even update the <
CODE>SCRIPT_URx</
CODE>
Use this directive to disable the module instead of commenting out
all <
CODE>RewriteRule</
CODE> directives!
Note that, by default, rewrite configurations are not inherited.
This means that you need to have a <
CODE>RewriteEngine on</
CODE>
directive for each virtual host you wish to use it in.
<
H3><
A NAME="RewriteOptions">RewriteOptions</
A></
H3>
><
STRONG>Syntax:</
STRONG></
A> <
CODE>RewriteOptions</
CODE> <
EM>Option</
EM><
BR>
><
STRONG>Default:</
STRONG></
A> <
EM>None</
EM><
BR>
><
STRONG>Context:</
STRONG></
A> server config, virtual host, directory,
><
STRONG>Override:</
STRONG></
A> FileInfo<
BR>
><
STRONG>Status:</
STRONG></
A> Extension<
BR>
><
STRONG>Compatibility:</
STRONG></
A> Apache 1.2<
BR>
The <
CODE>RewriteOptions</
CODE> directive sets some special options for the
current per-server or per-directory configuration. The <
EM>Option</
EM>
strings can be one of the following:
<
LI>'<
STRONG><
CODE>inherit</
CODE></
STRONG>'<
BR>
This forces the current configuration to inherit the configuration of the
parent. In per-virtual-server context this means that the maps,
conditions and rules of the main server gets inherited. In per-directory
context this means that conditions and rules of the parent directory's
<
CODE>.htaccess</
CODE> configuration gets inherited.
<
H3><
A NAME="RewriteLog">RewriteLog</
A></
H3>
><
STRONG>Syntax:</
STRONG></
A> <
CODE>RewriteLog</
CODE> <
EM>Filename</
EM><
BR>
><
STRONG>Default:</
STRONG></
A> <
EM>None</
EM><
BR>
><
STRONG>Context:</
STRONG></
A> server config, virtual host<
BR>
><
STRONG>Override:</
STRONG></
A> <
EM>Not applicable</
EM><
BR>
><
STRONG>Status:</
STRONG></
A> Extension<
BR>
><
STRONG>Compatibility:</
STRONG></
A> Apache 1.2<
BR>
The <
CODE>RewriteLog</
CODE> directive sets the name of the file to which the
server logs any rewriting actions it performs. If the name does not begin
with a slash ('<
CODE>/</
CODE>') then it is assumed to be relative to the
<
EM>Server Root</
EM>. The directive should occur only once per server
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
<
STRONG>Notice</
STRONG>: To disable the logging of rewriting actions it is
not recommended to set <
EM>Filename</
EM>
to <
CODE>/
dev/
null</
CODE>, because although the rewriting engine does
not create output to a logfile it still creates the logfile
output internally. <
STRONG>This will slow down the server with no advantage
to the administrator!</
STRONG>
To disable logging either remove or comment out the
<
CODE>RewriteLog</
CODE> directive or use <
CODE>RewriteLogLevel 0</
CODE>!
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
<
STRONG>Security</
STRONG>: See the <
ATips</
A> document for details on why your security could be compromised if the
directory where logfiles are stored is writable by anyone other than the user
<
STRONG>Example:</
STRONG>
<
H3><
A NAME="RewriteLogLevel">RewriteLogLevel</
A></
H3>
><
STRONG>Syntax:</
STRONG></
A> <
CODE>RewriteLogLevel</
CODE> <
EM>Level</
EM><
BR>
><
STRONG>Default:</
STRONG></
A> <
STRONG><
CODE>RewriteLogLevel 0</
CODE></
STRONG>
><
STRONG>Context:</
STRONG></
A> server config, virtual host<
BR>
><
STRONG>Override:</
STRONG></
A> <
EM>Not applicable</
EM><
BR>
><
STRONG>Status:</
STRONG></
A> Extension<
BR>
><
STRONG>Compatibility:</
STRONG></
A> Apache 1.2<
BR>
The <
CODE>RewriteLogLevel</
CODE> directive set the verbosity level of the
logfile. The default level 0 means no logging, while 9 or more means
that practically all actions are logged.
To disable the logging of rewriting actions simply set <
EM>Level</
EM> to 0.
This disables all rewrite action logs.
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
<
STRONG>Notice:</
STRONG> Using a high value for <
EM>Level</
EM> will slow down
server dramatically! Use the rewriting logfile only for debugging or at least
at <
EM>Level</
EM> not greater than 2!
<
STRONG>Example:</
STRONG>
<
H3><
A NAME="RewriteLock">RewriteLock</
A></
H3>
><
STRONG>Syntax:</
STRONG></
A> <
CODE>RewriteLock</
CODE> <
EM>Filename</
EM><
BR>
><
STRONG>Default:</
STRONG></
A> <
EM>None</
EM><
BR>
><
STRONG>Context:</
STRONG></
A> server config<
BR>
><
STRONG>Override:</
STRONG></
A> <
EM>Not applicable</
EM><
BR>
><
STRONG>Status:</
STRONG></
A> Extension<
BR>
><
STRONG>Compatibility:</
STRONG></
A> Apache 1.3<
BR>
This directive sets the filename for a synchronization lockfile which
mod_rewrite needs to communicate with <
SAMP>RewriteMap</
SAMP>
<
EM>programs</
EM>. Set this lockfile to a local path (not on a NFS-mounted
device) when you want to use a rewriting map-program. It is not required for
all other types of rewriting maps.
<
H3><
A NAME="RewriteMap">RewriteMap</
A></
H3>
><
STRONG>Syntax:</
STRONG></
A> <
CODE>RewriteMap</
CODE> <
EM>MapName </
EM>
<
EM>MapType</
EM><
CODE>:</
CODE><
EM>MapSource</
EM><
BR>
><
STRONG>Default:</
STRONG></
A> not used per default<
BR>
><
STRONG>Context:</
STRONG></
A> server config, virtual host<
BR>
><
STRONG>Override:</
STRONG></
A> <
EM>Not applicable</
EM><
BR>
><
STRONG>Status:</
STRONG></
A> Extension<
BR>
><
STRONG>Compatibility:</
STRONG></
A> Apache 1.2 (partially), Apache 1.3<
BR>
The <
CODE>RewriteMap</
CODE> directive defines a <
EM>Rewriting Map</
EM>
which can be used inside rule substitution strings by the mapping-functions
lookup can be of various types.
The <
A NAME="mapfunc"><
EM>MapName</
EM></
A> is the name of the map and will
be used to specify a mapping-function for the substitution strings of a
rewriting rule via one of the following constructs:
<
CODE>${</
CODE> <
EM>MapName</
EM> <
CODE>:</
CODE> <
EM>LookupKey</
EM>
<
CODE>${</
CODE> <
EM>MapName</
EM> <
CODE>:</
CODE> <
EM>LookupKey</
EM>
<
CODE>|</
CODE> <
EM>DefaultValue</
EM> <
CODE>}</
CODE>
When such a construct occurs the map <
EM>MapName</
EM>
is consulted and the key <
EM>LookupKey</
EM> is looked-up. If the key is
found, the map-function construct is substituted by <
EM>SubstValue</
EM>. If
the key is not found then it is substituted by <
EM>DefaultValue</
EM> or
the empty string if no <
EM>DefaultValue</
EM> was specified.
The following combinations for <
EM>MapType</
EM> and <
EM>MapSource</
EM>
<
LI><
STRONG>Standard Plain Text</
STRONG><
BR>
MapType: <
CODE>txt</
CODE>, MapSource: Unix filesystem path to valid regular
This is the standard rewriting map feature where the <
EM>MapSource</
EM> is
a plain ASCII file containing either blank lines, comment lines (starting
with a '#' character) or pairs like the following - one per line.
<
EM>MatchingKey</
EM> <
EM>SubstValue</
EM>
<
TABLE BORDER=0 CELLSPACING=1 CELLPADDING=5 BGCOLOR="#F0F0F0">
<
TABLE BORDER=0 CELLSPACING=1 CELLPADDING=5 BGCOLOR="#F0F0F0">
<
LI><
STRONG>Randomized Plain Text</
STRONG><
BR>
MapType: <
CODE>rnd</
CODE>, MapSource: Unix filesystem path to valid regular
This is identical to the Standard Plain Text variant above but with a
post-processing feature: After looking up a value it is parsed according
to contained ``<
CODE>|</
CODE>'' characters which have the meaning of
in other words: they indicate a set of alternatives from which the actual
returned value is chosen randomly. Although this sounds crazy and useless,
was actually designed for load balancing in a reverse proxy situation where
the looked up values are server names.
<
TABLE BORDER=0 CELLSPACING=1 CELLPADDING=5 BGCOLOR="#F0F0F0">
static www1|www2|www3|www4
<
TABLE BORDER=0 CELLSPACING=1 CELLPADDING=5 BGCOLOR="#F0F0F0">
<
LI><
STRONG>Hash File</
STRONG><
BR>
MapType: <
CODE>dbm</
CODE>, MapSource: Unix filesystem path to valid
Here the source is a binary NDBM format file containing the same contents
as a <
EM>Plain Text</
EM> format file, but in a special representation
which is optimized for really fast lookups. You can create such a file with
any NDBM tool or with the following Perl script:
<
TABLE BORDER=0 CELLSPACING=1 CELLPADDING=5 BGCOLOR="#F0F0F0">
## txt2dbm -- convert txt map to dbm format
($txtmap, $dbmmap) = @ARGV;
open(TXT, "<$txtmap");
dbmopen(%DB, $dbmmap, 0644);
next if (m|^s*#.*| or m|^s*$|);
$DB{$1} = $2 if (m|^\s*(\S+)\s+(\S+)$|);
close(TXT)</
PRE></
TD></
TR>
<
TABLE BORDER=0 CELLSPACING=1 CELLPADDING=5 BGCOLOR="#F0F0F0">
<
LI><
STRONG>Internal Function</
STRONG><
BR>
MapType: <
CODE>int</
CODE>, MapSource: Internal Apache function
Here the source is an internal Apache function. Currently you cannot
create your own, but the following functions already exists:
<
LI><
STRONG>toupper</
STRONG>:<
BR>
Converts the looked up key to all upper case.
<
LI><
STRONG>tolower</
STRONG>:<
BR>
Converts the looked up key to all lower case.
<
LI><
STRONG>escape</
STRONG>:<
BR>
Translates special characters in the looked up key to hex-encodings.
<
LI><
STRONG>unescape</
STRONG>:<
BR>
Translates hex-encodings in the looked up key back to special characters.
<
LI><
STRONG>External Rewriting Program</
STRONG><
BR>
MapType: <
CODE>prg</
CODE>, MapSource: Unix filesystem path to valid
Here the source is a Unix program, not a map file. To create it you can use
the language of your choice, but the result has to be a run-able Unix
executable (<
EM>
i.e.</
EM>, either object-code or a script with the
This program gets started once at startup of the Apache servers and then
communicates with the rewriting engine over its <
CODE>stdin</
CODE> and
<
CODE>stdout</
CODE> file-handles. For each map-function lookup it will
receive the key to lookup as a newline-terminated string on
<
CODE>stdin</
CODE>. It then has to give back the looked-up value as a
newline-terminated string on <
CODE>stdout</
CODE> or the four-character
string ``<
CODE>NULL</
CODE>'' if it fails (<
EM>
i.e.</
EM>, there is no
for the given key). A trivial program which will implement a 1:1 map
(<
EM>
i.e.</
EM>, key == value) could be:
<
TABLE BORDER=0 CELLSPACING=1 CELLPADDING=5 BGCOLOR="#F0F0F0">
# or lookups should occur...
<
LI>``<
EM>Keep the program simple, stupid</
EM>'' (KISS), because
if this program hangs it will lead to a hang of the Apache server
<
LI>Avoid one common mistake: never do buffered I/O on <
CODE>stdout</
CODE>!
This will cause a deadloop! Hence the ``<
CODE>$|=1</
CODE>'' in the
<
LI>Use the <
SAMP>RewriteLock</
SAMP> directive to define a lockfile
mod_rewrite can use to synchronize the communication to the program.
Per default no such synchronization takes place.
The <
CODE>RewriteMap</
CODE> directive can occur more than once. For each
mapping-function use one <
CODE>RewriteMap</
CODE> directive to declare its
rewriting mapfile. While you cannot <
STRONG>declare</
STRONG> a map in
per-directory context it is of course possible to <
STRONG>use</
STRONG>
this map in per-directory context.
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
<
STRONG>Notice:</
STRONG> For plain text and DBM format files the looked-up
until the <
CODE>mtime</
CODE> of the mapfile changes or the server does a
restart. This way you can have map-functions in rules which are used
for <
STRONG>every</
STRONG> request. This is no problem, because the
external lookup only happens once!
<
H3><
A NAME="RewriteBase">RewriteBase</
A></
H3>
><
STRONG>Syntax:</
STRONG></
A> <
CODE>RewriteBase</
CODE> <
EM>BaseURL</
EM><
BR>
><
STRONG>Default:</
STRONG></
A> <
EM>default is the physical directory path</
EM>
><
STRONG>Context:</
STRONG></
A> directory, .htaccess<
BR>
><
STRONG>Override:</
STRONG></
A> <
EM>FileInfo</
EM><
BR>
><
STRONG>Status:</
STRONG></
A> Extension<
BR>
><
STRONG>Compatibility:</
STRONG></
A> Apache 1.2<
BR>
The <
CODE>RewriteBase</
CODE> directive explicitly sets the base URL for
per-directory rewrites. As you will see below, <
CODE>RewriteRule</
CODE> can be
used in per-directory config files (<
CODE>.htaccess</
CODE>). There it will act
locally, <
EM>
i.e.</
EM>, the local directory prefix is stripped at this stage of
processing and your rewriting rules act only on the remainder. At the end
it is automatically added.
When a substitution occurs for a new URL, this module has to re-inject the URL
into the server processing. To be able to do this it needs to know what the
corresponding URL-prefix or URL-base is. By default this prefix is the
corresponding filepath itself. <
STRONG>But at most websites URLs are
<
STRONG>NOT</
STRONG> directly related to physical filename paths, so this
assumption will be usually be wrong!</
STRONG> There you have to use the
<
CODE>RewriteBase</
CODE> directive to specify the correct URL-prefix.
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
<
STRONG>Notice:</
STRONG> If your webserver's URLs are <
STRONG>not</
STRONG>
directly related to physical file paths, you have to use
<
CODE>RewriteBase</
CODE> in every
<
CODE>.htaccess</
CODE> files where you want to use <
CODE>RewriteRule</
CODE>
<
STRONG>Example:</
STRONG>
Assume the following per-directory config file:
<
TABLE BORDER=0 CELLSPACING=1 CELLPADDING=5 BGCOLOR="#F0F0F0">
# Remember: /
abc/
def is the physical path of /xyz, <
EM>
i.e.</
EM>, the server
# has a 'Alias /xyz /
abc/
def' directive <
EM>
e.g.</
EM>
# let the server know that we are reached via /xyz and not
# via the physical path prefix /
abc/
def# now the rewriting rules
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
<
STRONG>Notice - For the Apache hackers:</
STRONG><
BR>
The following list gives detailed information about the internal
This seems very complicated but is the correct Apache internal processing,
because the per-directory rewriting comes too late in the process. So,
when it occurs the (rewritten) request has to be re-injected into the Apache
kernel! BUT: While this seems like a serious overhead, it really isn't, because
this re-injection happens fully internal to the Apache server and the same
procedure is used by many other operations inside Apache. So, you can be
sure the design and implementation is correct.
<
H3><
A NAME="RewriteCond">RewriteCond</
A></
H3>
><
STRONG>Syntax:</
STRONG></
A> <
CODE>RewriteCond</
CODE> <
EM>TestString</
EM>
><
STRONG>Default:</
STRONG></
A> <
EM>None</
EM><
BR>
><
STRONG>Context:</
STRONG></
A> server config, virtual host, directory,
><
STRONG>Override:</
STRONG></
A> <
EM>FileInfo</
EM><
BR>
><
STRONG>Status:</
STRONG></
A> Extension<
BR>
><
STRONG>Compatibility:</
STRONG></
A> Apache 1.2 (partially), Apache 1.3<
BR>
The <
CODE>RewriteCond</
CODE> directive defines a rule condition. Precede a
<
CODE>RewriteRule</
CODE> directive with one or more <
CODE>RewriteCond</
CODE>
The following rewriting rule is only used if its pattern matches the current
state of the URI <
STRONG>and</
STRONG> if these additional conditions apply
<
EM>TestString</
EM> is a string which can contains the following
expanded constructs in addition to plain text:
<
LI><
STRONG>RewriteRule backreferences</
STRONG>: These are backreferences of
(0 <= N <= 9) which provide access to the grouped parts (parenthesis!)
of the pattern from the corresponding <
CODE>RewriteRule</
CODE> directive (the
one following the current bunch of <
CODE>RewriteCond</
CODE> directives).
<
LI><
STRONG>RewriteCond backreferences</
STRONG>: These are backreferences of
(1 <= N <= 9) which provide access to the grouped parts (parenthesis!) of
the pattern from the last matched <
CODE>RewriteCond</
CODE> directive in the
current bunch of conditions.
<
LI><
STRONG>Server-Variables</
STRONG>: These are variables
<
CODE>%{</
CODE> <
EM>NAME_OF_VARIABLE</
EM> <
CODE>}</
CODE>
where <
EM>NAME_OF_VARIABLE</
EM> can be a string
<
TABLE BGCOLOR="#F0F0F0" CELLSPACING=0 CELLPADDING=5>
<
STRONG>HTTP headers:</
STRONG><
P>
HTTP_PROXY_CONNECTION<
BR>
<
STRONG>connection & request:</
STRONG><
P>
<
STRONG>server internals:</
STRONG><
P>
<
STRONG>system stuff:</
STRONG><
P>
<
STRONG>specials:</
STRONG><
P>
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
<
STRONG>Notice:</
STRONG> These variables all correspond to the similar named
HTTP MIME-headers, C variables of the Apache server or <
CODE>struct tm</
CODE>
fields of the Unix system.
<
LI>The variables SCRIPT_FILENAME and REQUEST_FILENAME contain the same
value, <
EM>
i.e.</
EM>, the value of the <
CODE>filename</
CODE> field of
<
CODE>request_rec</
CODE> structure of the Apache server. The first name is
commonly known CGI variable name while the second is the consistent
counterpart to REQUEST_URI (which contains the value of the <
CODE>uri</
CODE>
field of <
CODE>request_rec</
CODE>).
<
LI>There is the special format: <
CODE>%{ENV:variable}</
CODE> where
<
EM>variable</
EM> can be any environment variable. This is looked-up via
internal Apache structures and (if not found there) via <
CODE>getenv()</
CODE>
from the Apache server process.
<
LI>There is the special format: <
CODE>%{HTTP:header}</
CODE> where
<
EM>header</
EM> can be any HTTP MIME-header name. This is looked-up
from the HTTP request. Example: <
CODE>%{HTTP:Proxy-Connection}</
CODE>
is the value of the HTTP header ``<
CODE>Proxy-Connection:</
CODE>''.
<
LI>There is the special format <
CODE>%{LA-U:variable}</
CODE> for look-aheads
which perform an internal (URL-based) sub-request to determine the final value
of <
EM>variable</
EM>. Use this when you want to use a variable for rewriting
which actually is set later in an API phase and thus is not available at the
current stage. For instance when you want to rewrite according to the
<
CODE>REMOTE_USER</
CODE> variable from within the per-server context
(<
CODE>
httpd.conf</
CODE> file) you have to use <
CODE>%{LA-U:REMOTE_USER}</
CODE>
because this variable is set by the authorization phases which come
<
EM>after</
EM> the URL translation phase where mod_rewrite operates. On the
other hand, because mod_rewrite implements its per-directory context
(<
CODE>.htaccess</
CODE> file) via the Fixup phase of the API and because the
authorization phases come <
EM>before</
EM> this phase, you just can use
<
CODE>%{REMOTE_USER}</
CODE> there.
<
LI>There is the special format: <
CODE>%{LA-F:variable}</
CODE> which perform an
internal (filename-based) sub-request to determine the final value of
<
EM>variable</
EM>. This is the most of the time the same as LA-U above.
<
EM>CondPattern</
EM> is the condition pattern, <
EM>
i.e.</
EM>, a regular
which gets applied to the current instance of the <
EM>TestString</
EM>,
<
EM>
i.e.</
EM>, <
EM>TestString</
EM> gets evaluated and then matched against
<
STRONG>Remember:</
STRONG> <
EM>CondPattern</
EM> is a standard
<
EM>Extended Regular Expression</
EM> with some additions:
<
LI>You can precede the pattern string with a '<
CODE>!</
CODE>' character
(exclamation mark) to specify a <
STRONG>non</
STRONG>-matching pattern.
There are some special variants of <
EM>CondPatterns</
EM>. Instead of real
regular expression strings you can also use one of the following:
<
LI>'<
STRONG><CondPattern</
STRONG>' (is lexicographically lower)<
BR>
Treats the <
EM>CondPattern</
EM> as a plain string and compares it
lexicographically to <
EM>TestString</
EM> and results in a true expression if
<
EM>TestString</
EM> is lexicographically lower than <
EM>CondPattern</
EM>.
<
LI>'<
STRONG>>CondPattern</
STRONG>' (is lexicographically greater)<
BR>
Treats the <
EM>CondPattern</
EM> as a plain string and compares it
lexicographically to <
EM>TestString</
EM> and results in a true expression if
<
EM>TestString</
EM> is lexicographically greater than <
EM>CondPattern</
EM>.
<
LI>'<
STRONG>=CondPattern</
STRONG>' (is lexicographically equal)<
BR>
Treats the <
EM>CondPattern</
EM> as a plain string and compares it
lexicographically to <
EM>TestString</
EM> and results in a true expression if
<
EM>TestString</
EM> is lexicographically equal to <
EM>CondPattern</
EM>,
i.e the
two strings are exactly equal (character by character).
If <
EM>CondPattern</
EM> is just <
SAMP>""</
SAMP> (two quotation marks) this
compares <
EM>TestString</
EM> against the empty string.
<
LI>'<
STRONG>-d</
STRONG>' (is <
STRONG>d</
STRONG>irectory)<
BR>
Treats the <
EM>TestString</
EM> as a pathname and
tests if it exists and is a directory.
<
LI>'<
STRONG>-f</
STRONG>' (is regular <
STRONG>f</
STRONG>ile)<
BR>
Treats the <
EM>TestString</
EM> as a pathname and
tests if it exists and is a regular file.
<
LI>'<
STRONG>-s</
STRONG>' (is regular file with <
STRONG>s</
STRONG>ize)<
BR>
Treats the <
EM>TestString</
EM> as a pathname and
tests if it exists and is a regular file with size greater than zero.
<
LI>'<
STRONG>-l</
STRONG>' (is symbolic <
STRONG>l</
STRONG>ink)<
BR>
Treats the <
EM>TestString</
EM> as a pathname and
tests if it exists and is a symbolic link.
<
LI>'<
STRONG>-F</
STRONG>' (is existing file via subrequest)<
BR>
Checks if <
EM>TestString</
EM> is a valid file and accessible via all the
server's currently-configured access controls for that path. This uses an
internal subrequest to determine the check, so use it with care because it
decreases your servers performance!
<
LI>'<
STRONG>-U</
STRONG>' (is existing URL via subrequest)<
BR>
Checks if <
EM>TestString</
EM> is a valid URL and accessible via all the
currently-configured access controls for that path. This uses an internal
subrequest to determine the check, so use it with care because it decreases
your server's performance!
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
All of these tests can also be prefixed by a not ('!') character
Additionally you can set special flags for <
EM>CondPattern</
EM> by appending
<
CODE>[</
CODE><
EM>flags</
EM><
CODE>]</
CODE>
as the third argument to the <
CODE>RewriteCond</
CODE> directive. <
EM>Flags</
EM>
is a comma-separated list of the following flags:
<
LI>'<
STRONG><
CODE>nocase|NC</
CODE></
STRONG>' (<
STRONG>n</
STRONG>o <
STRONG>c</
STRONG>ase)<
BR>
This makes the condition test case-insensitive, <
EM>
i.e.</
EM>, there is
no difference between 'A-Z' and 'a-z' both in the expanded
<
EM>TestString</
EM> and the <
EM>CondPattern</
EM>.
<
LI>'<
STRONG><
CODE>ornext|OR</
CODE></
STRONG>' (<
STRONG>or</
STRONG> next condition)<
BR>
Use this to combine rule conditions with a local OR instead of the
implicit AND. Typical example:
RewriteCond %{REMOTE_HOST} ^host1.* [OR]
RewriteCond %{REMOTE_HOST} ^host2.* [OR]
RewriteCond %{REMOTE_HOST} ^host3.*
RewriteRule
...some special stuff for any of these hosts...
Without this flag you had to write down the
cond/
rule three times.
<
STRONG>Example:</
STRONG>
To rewrite the Homepage of a site according to the ``<
CODE>User-Agent:</
CODE>''
header of the request, you can use the following:
RewriteCond %{HTTP_USER_AGENT} ^Mozilla.*
RewriteCond %{HTTP_USER_AGENT} ^Lynx.*
Interpretation: If you use Netscape Navigator as your browser (which identifies
itself as 'Mozilla'), then you get the max homepage, which includes
Frames, <
EM>etc.</
EM> If you use the Lynx browser (which is Terminal-based), then you
get the min homepage, which contains no images, no tables, <
EM>etc.</
EM> If you
use any other browser you get the standard homepage.
<
H3><
A NAME="RewriteRule">RewriteRule</
A></
H3>
><
STRONG>Syntax:</
STRONG></
A> <
CODE>RewriteRule</
CODE> <
EM>Pattern</
EM> <
EM>Substitution</
EM><
BR>
><
STRONG>Default:</
STRONG></
A> <
EM>None</
EM><
BR>
><
STRONG>Context:</
STRONG></
A> server config, virtual host, directory, .htaccess<
BR>
><
STRONG>Override:</
STRONG></
A> <
EM>FileInfo</
EM><
BR>
><
STRONG>Status:</
STRONG></
A> Extension<
BR>
><
STRONG>Compatibility:</
STRONG></
A> Apache 1.2 (partially), Apache 1.3<
BR>
The <
CODE>RewriteRule</
CODE> directive is the real rewriting workhorse. The
directive can occur more than once. Each directive then defines one single
rewriting rule. The <
STRONG>definition order</
STRONG> of these rules is
<
STRONG>important</
STRONG>, because this order is used when applying the rules at
<
A NAME="patterns"><
EM>Pattern</
EM></
A> can be (for Apache
1.1.x a System
V8 and for Apache
1.2.x a POSIX) <
A NAME="regexp">regular expression</
A>
which gets applied to the current URL. Here ``current'' means the value of the
URL when this rule gets applied. This may not be the original requested
URL, because there could be any number of rules before which already matched
and made alterations to it.
Some hints about the syntax of regular expressions:
<
TABLE BGCOLOR="#F0F0F0" CELLSPACING=0 CELLPADDING=5>
<
STRONG><
CODE>.</
CODE></
STRONG> Any single character
<
STRONG><
CODE>[</
CODE></
STRONG>chars<
STRONG><
CODE>]</
CODE></
STRONG> Character class: One of chars
<
STRONG><
CODE>[^</
CODE></
STRONG>chars<
STRONG><
CODE>]</
CODE></
STRONG> Character class: None of chars
text1<
STRONG><
CODE>|</
CODE></
STRONG>text2 Alternative: text1 or text2
<
STRONG>Quantifiers:</
STRONG>
<
STRONG><
CODE>?</
CODE></
STRONG> 0 or 1 of the preceding text
<
STRONG><
CODE>*</
CODE></
STRONG> 0 or N of the preceding text (N > 1)
<
STRONG><
CODE>+</
CODE></
STRONG> 1 or N of the preceding text (N > 1)
<
STRONG>Grouping:</
STRONG>
<
STRONG><
CODE>(</
CODE></
STRONG>text<
STRONG><
CODE>)</
CODE></
STRONG> Grouping of text
(either to set the borders of an alternative or
for making backreferences where the <
STRONG>N</
STRONG>th group can
be used on the RHS of a RewriteRule with <
CODE>$</
CODE><
STRONG>N</
STRONG>)
<
STRONG>Anchors:</
STRONG>
<
STRONG><
CODE>^</
CODE></
STRONG> Start of line anchor
<
STRONG><
CODE>$</
CODE></
STRONG> End of line anchor
<
STRONG>Escaping:</
STRONG>
<
STRONG><
CODE>\</
CODE></
STRONG>char escape that particular char
(for instance to specify the chars "<
CODE>.[]()</
CODE>" <
EM>etc.</
EM>)
For more information about regular expressions either have a look at your
Apache 1.3 distribution. When you are interested in more detailed and deeper
information about regular expressions and its variants (POSIX regex, Perl
regex, <
EM>etc.</
EM>) have a look at the following dedicated book on this topic:
<
EM>Mastering Regular Expressions</
EM><
BR>
Nutshell Handbook Series<
BR>
O'Reilly & Associates, Inc. 1997<
BR>
Additionally in mod_rewrite the NOT character ('<
CODE>!</
CODE>') is a possible
pattern prefix. This gives you the ability to negate a pattern; to say, for
instance: ``<
EM>if the current URL does <
STRONG>NOT</
STRONG> match to this
pattern</
EM>''. This can be used for special cases where it is better to match
the negative pattern or as a last default rule.
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
<
STRONG>Notice:</
STRONG> When using the NOT character to negate a pattern you cannot
have grouped wildcard parts in the pattern. This is impossible because when
the pattern does NOT match, there are no contents for the groups. In
consequence, if negated patterns are used, you cannot use <
CODE>$N</
CODE> in the
<
A NAME="rhs"><
EM>Substitution</
EM></
A> of a rewriting rule is the string
which is substituted for (or replaces) the original URL for which
<
EM>Pattern</
EM> matched. Beside plain text you can use
<
LI>back-references <
CODE>$N</
CODE> to the RewriteRule pattern
<
LI>back-references <
CODE>%N</
CODE> to the last matched RewriteCond pattern
<
LI>server-variables as in rule condition test-strings (<
CODE>%{VARNAME}</
CODE>)
<
LI><
A HREF="#mapfunc">mapping-function</
A> calls (<
CODE>${mapname:key|default}</
CODE>)
Back-references are <
CODE>$</
CODE><
STRONG>N</
STRONG> (<
STRONG>N</
STRONG>=0..9) identifiers which
will be replaced by the contents of the <
STRONG>N</
STRONG>th group of the matched
<
EM>Pattern</
EM>. The server-variables are the same as for the
<
EM>TestString</
EM> of a <
CODE>RewriteCond</
CODE> directive. The
mapping-functions come from the <
CODE>RewriteMap</
CODE> directive and are
explained there. These three types of variables are expanded in the order of
As already mentioned above, all the rewriting rules are applied to the
<
EM>Substitution</
EM> (in the order of definition in the config file). The
URL is <
STRONG>completely replaced</
STRONG> by the <
EM>Substitution</
EM> and the
rewriting process goes on until there are no more rules (unless explicitly
terminated by a <
CODE><
STRONG>L</
STRONG></
CODE> flag - see below).
There is a special substitution string named '<
CODE>-</
CODE>' which means:
<
STRONG>NO substitution</
STRONG>! Sounds silly? No, it is useful to provide rewriting
rules which <
STRONG>only</
STRONG> match some URLs but do no substitution, <
EM>
e.g.</
EM>, in
conjunction with the <
STRONG>C</
STRONG> (chain) flag to be able to have more than one
pattern to be applied before a substitution occurs.
One more note: You can even create URLs in the substitution string containing
a query string part. Just use a question mark inside the substitution string
to indicate that the following stuff should be re-injected into the
QUERY_STRING. When you want to erase an existing query string, end the
substitution string with just the question mark.
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
<
STRONG>Notice</
STRONG>: There is a special feature. When you prefix a substitution
field with <
CODE>http://</
CODE><
EM>thishost</
EM>[<
EM>:thisport</
EM>] then
<
STRONG>mod_rewrite</
STRONG> automatically strips it out. This auto-reduction on
implicit external redirect URLs is a useful and important feature when
used in combination with a mapping-function which generates the hostname
part. Have a look at the first example in the example section below to
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
<
STRONG>Remember:</
STRONG> An unconditional external redirect to your own server will
not work with the prefix <
CODE>
http://thishost</
CODE> because of this feature.
To achieve such a self-redirect, you have to use the <
STRONG>R</
STRONG>-flag (see
Additionally you can set special flags for <
EM>Substitution</
EM> by appending
<
CODE>[</
CODE><
EM>flags</
EM><
CODE>]</
CODE>
as the third argument to the <
CODE>RewriteRule</
CODE> directive. <
EM>Flags</
EM> is a
comma-separated list of the following flags:
<
LI>'<
STRONG><
CODE>redirect|R</
CODE> [=<
EM>code</
EM>]</
STRONG>' (force <
A NAME="redirect"><
STRONG>r</
STRONG>edirect</
A>)<
BR>
Prefix <
EM>Substitution</
EM>
with <
CODE>
http://thishost[:thisport]/</
CODE> (which makes the new URL a URI) to
force a external redirection. If no <
EM>code</
EM> is given a HTTP response
of 302 (MOVED TEMPORARILY) is used. If you want to use other response
codes in the range 300-400 just specify them as a number or use
one of the following symbolic names: <
CODE>temp</
CODE> (default), <
CODE>permanent</
CODE>,
Use it for rules which should
canonicalize the URL and gives it back to the client, <
EM>
e.g.</
EM>, translate
``<
CODE>/~</
CODE>'' into ``<
CODE>/u/</
CODE>'' or always append a slash to
<
CODE>/u/</
CODE><
EM>user</
EM>, etc.<
BR>
<
STRONG>Notice:</
STRONG> When you use this flag, make sure that the
substitution field is a valid URL! If not, you are redirecting to an
invalid location! And remember that this flag itself only prefixes the
Usually you also want to stop and do the redirection immediately. To stop
the rewriting you also have to provide the 'L' flag.
<
LI>'<
STRONG><
CODE>forbidden|F</
CODE></
STRONG>' (force URL to be <
STRONG>f</
STRONG>orbidden)<
BR>
This forces the current URL to be forbidden, <
EM>
i.e.</
EM>, it immediately sends
back a HTTP response of 403 (FORBIDDEN). Use this flag in conjunction with
appropriate RewriteConds to conditionally block some URLs.
<
LI>'<
STRONG><
CODE>gone|G</
CODE></
STRONG>' (force URL to be <
STRONG>g</
STRONG>one)<
BR>
This forces the current URL to be gone, <
EM>
i.e.</
EM>, it immediately sends back a
HTTP response of 410 (GONE). Use this flag to mark no longer existing
<
LI>'<
STRONG><
CODE>proxy|P</
CODE></
STRONG>' (force <
STRONG>p</
STRONG>roxy)<
BR>
This flag forces the substitution part to be internally forced as a proxy
request and immediately (<
EM>
i.e.</
EM>, rewriting rule processing stops here) put
through the <
A HREF="mod_proxy.html">proxy module</
A>. You have to make
sure that the substitution string is a valid URI (<
EM>
e.g.</
EM>, typically starting
with <
CODE>http://</
CODE><
EM>hostname</
EM>) which can be handled by the
Apache proxy module. If not you get an error from the proxy module. Use
this flag to achieve a more powerful implementation of the <
A remote stuff into the namespace of the local server.
Notice: To use this functionality make sure you have the proxy module
compiled into your Apache server program. If you don't know please check
whether <
CODE>
mod_proxy.c</
CODE> is part of the ``<
CODE>httpd -l</
CODE>''
output. If yes, this functionality is available to mod_rewrite. If not,
then you first have to rebuild the ``<
CODE>httpd</
CODE>'' program with
<
LI>'<
STRONG><
CODE>last|L</
CODE></
STRONG>' (<
STRONG>l</
STRONG>ast rule)<
BR>
Stop the rewriting process here and
don't apply any more rewriting rules. This corresponds to the Perl
<
CODE>last</
CODE> command or the <
CODE>break</
CODE> command from the C
language. Use this flag to prevent the currently rewritten URL from being
rewritten further by following rules which may be wrong. For
example, use it to rewrite the root-path URL ('<
CODE>/</
CODE>') to a real
one, <
EM>
e.g.</
EM>, '<
CODE>/
e/
www/</
CODE>'.
<
LI>'<
STRONG><
CODE>next|N</
CODE></
STRONG>' (<
STRONG>n</
STRONG>ext round)<
BR>
Re-run the rewriting process (starting again with the first rewriting
rule). Here the URL to match is again not the original URL but the URL
from the last rewriting rule. This corresponds to the Perl
<
CODE>next</
CODE> command or the <
CODE>continue</
CODE> command from the C
language. Use this flag to restart the rewriting process, <
EM>
i.e.</
EM>, to
immediately go to the top of the loop. <
BR>
<
STRONG>But be careful not to create a deadloop!</
STRONG>
<
LI>'<
STRONG><
CODE>chain|C</
CODE></
STRONG>' (<
STRONG>c</
STRONG>hained with next rule)<
BR>
This flag chains the current rule with the next rule (which itself can
also be chained with its following rule, <
EM>etc.</
EM>). This has the following
effect: if a rule matches, then processing continues as usual, <
EM>
i.e.</
EM>, the
flag has no effect. If the rule does <
STRONG>not</
STRONG> match, then all following
chained rules are skipped. For instance, use it to remove the
``<
CODE>.www</
CODE>'' part inside a per-directory rule set when you let an
external redirect happen (where the ``<
CODE>.www</
CODE>'' part should not to
<
LI>'<
STRONG><
CODE>type|T</
CODE></
STRONG>=<
EM>MIME-type</
EM>' (force MIME <
STRONG>t</
STRONG>ype)<
BR>
Force the MIME-type of the target file to be <
EM>MIME-type</
EM>. For
instance, this can be used to simulate the <
CODE>mod_alias</
CODE>
directive <
CODE>ScriptAlias</
CODE> which internally forces all files inside
the mapped directory to have a MIME type of
<
LI>'<
STRONG><
CODE>nosubreq|NS</
CODE></
STRONG>' (used only if <
STRONG>n</
STRONG>o internal <
STRONG>s</
STRONG>ub-request)<
BR>
This flag forces the rewriting engine to skip a rewriting rule if the
current request is an internal sub-request. For instance, sub-requests
occur internally in Apache when <
CODE>mod_include</
CODE> tries to find out
information about possible directory default files (<
CODE>
index.xxx</
CODE>).
On sub-requests it is not always useful and even sometimes causes a failure to
if the complete set of rules are applied. Use this flag to exclude some rules.<
BR>
Use the following rule for your decision: whenever you prefix some URLs
with CGI-scripts to force them to be processed by the CGI-script, the
chance is high that you will run into problems (or even overhead) on sub-requests.
In these cases, use this flag.
<
LI>'<
STRONG><
CODE>nocase|NC</
CODE></
STRONG>' (<
STRONG>n</
STRONG>o <
STRONG>c</
STRONG>ase)<
BR>
This makes the <
EM>Pattern</
EM> case-insensitive, <
EM>
i.e.</
EM>, there is
no difference between 'A-Z' and 'a-z' when <
EM>Pattern</
EM> is matched
<
LI>'<
STRONG><
CODE>qsappend|QSA</
CODE></
STRONG>' (<
STRONG>q</
STRONG>uery <
STRONG>s</
STRONG>tring
<
STRONG>a</
STRONG>ppend)<
BR>
This flag forces the rewriting engine to append a query
string part in the substitution string to the existing one instead of
replacing it. Use this when you want to add more data to the query string
<
LI>'<
STRONG><
CODE>passthrough|PT</
CODE></
STRONG>' (<
STRONG>p</
STRONG>ass <
STRONG>t</
STRONG>hrough to next handler)<
BR>
This flag forces the rewriting engine to set the <
CODE>uri</
CODE> field
of the internal <
CODE>request_rec</
CODE> structure to the value
of the <
CODE>filename</
CODE> field. This flag is just a hack to be able
to post-process the output of <
CODE>RewriteRule</
CODE> directives by
<
CODE>Alias</
CODE>, <
CODE>ScriptAlias</
CODE>, <
CODE>Redirect</
CODE>, <
EM>etc.</
EM> directives
from other URI-to-filename translators. A trivial example to show the
If you want to rewrite <
CODE>/abc</
CODE> to <
CODE>/def</
CODE> via the rewriting
engine of <
CODE>mod_rewrite</
CODE> and then <
CODE>/def</
CODE> to <
CODE>/ghi</
CODE>
with <
CODE>mod_alias</
CODE>:
RewriteRule ^/abc(.*) /def$1 [PT]
If you omit the <
CODE>PT</
CODE> flag then <
CODE>mod_rewrite</
CODE>
will do its job fine, <
EM>
i.e.</
EM>, it rewrites <
CODE>uri=/abc/...</
CODE> to
<
CODE>filename=/def/...</
CODE> as a full API-compliant URI-to-filename
translator should do. Then <
CODE>mod_alias</
CODE> comes and tries to do a
URI-to-filename transition which will not work.
Notice: <
STRONG>You have to use this flag if you want to intermix directives
of different modules which contain URL-to-filename translators</
STRONG>. The
typical example is the use of <
CODE>mod_alias</
CODE> and
<
CODE>mod_rewrite</
CODE>..
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
<
STRONG>Notice - For the Apache hackers:</
STRONG><
BR>
If the current Apache API had a
filename-to-filename hook additionally to the URI-to-filename hook then
we wouldn't need this flag! But without such a hook this flag is the
only solution. The Apache Group has discussed this problem and will
add such hooks into Apache version 2.0.
<
LI>'<
STRONG><
CODE>skip|S</
CODE></
STRONG>=<
EM>num</
EM>' (<
STRONG>s</
STRONG>kip next rule(s))<
BR>
This flag forces the rewriting engine to skip the next <
EM>num</
EM> rules
in sequence when the current rule matches. Use this to make pseudo
if-then-else constructs: The last rule of the then-clause becomes
a <
CODE>skip=N</
CODE> where N is the number of rules in the else-clause.
(This is <
STRONG>not</
STRONG> the same as the 'chain|C' flag!)
<
LI>'<
STRONG><
CODE>env|E=</
CODE></
STRONG><
EM>VAR</
EM>:<
EM>VAL</
EM>' (set <
STRONG>e</
STRONG>nvironment variable)<
BR>
This forces an environment variable named <
EM>VAR</
EM> to be set to the
value <
EM>VAL</
EM>, where <
EM>VAL</
EM> can contain regexp backreferences
<
CODE>$N</
CODE> and <
CODE>%N</
CODE> which will be expanded. You can use this flag
more than once to set more than one variable. The variables can be later
dereferenced at a lot of situations, but the usual location will be from
within XSSI (via <
CODE><!--#echo var="VAR"--></
CODE>) or CGI (<
EM>
e.g.</
EM>
<
CODE>$ENV{'VAR'}</
CODE>). But additionally you can also dereference it in a
following RewriteCond pattern via <
CODE>%{ENV:VAR}</
CODE>. Use this to strip
but remember information from URLs.
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
<
STRONG>Notice:</
STRONG> Never forget that <
EM>Pattern</
EM> gets applied to a complete URL
in per-server configuration files. <
STRONG>But in per-directory configuration
files, the per-directory prefix (which always is the same for a specific
directory!) gets automatically <
EM>removed</
EM> for the pattern matching and
automatically <
EM>added</
EM> after the substitution has been done.</
STRONG> This feature is
essential for many sorts of rewriting, because without this prefix stripping
you have to match the parent directory which is not always possible.
There is one exception: If a substitution string starts with
``<
CODE>http://</
CODE>'' then the directory prefix will be <
STRONG>not</
STRONG> added and a
external redirect or proxy throughput (if flag <
STRONG>P</
STRONG> is used!) is forced!
<
TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10>
<
STRONG>Notice:</
STRONG> To enable the rewriting engine for per-directory configuration files
you need to set ``<
CODE>RewriteEngine On</
CODE>'' in these files <
STRONG>and</
STRONG>
``<
CODE>Option FollowSymLinks</
CODE>'' enabled. If your administrator has
disabled override of <
CODE>FollowSymLinks</
CODE> for a user's directory, then
you cannot use the rewriting engine. This restriction is needed for
Here are all possible substitution combinations and their meanings:
<
STRONG>Inside per-server configuration (<
CODE>
httpd.conf</
CODE>)<
BR>
<
TABLE BGCOLOR="#F0F0F0" CELLSPACING=0 CELLPADDING=5>
<
STRONG>Given Rule</
STRONG> <
STRONG>Resulting Substitution</
STRONG>
---------------------------------------------- ----------------------------------
^/somepath(.*) otherpath$1 not supported, because invalid!
^/somepath(.*) otherpath$1 [R] not supported, because invalid!
^/somepath(.*) otherpath$1 [P] not supported, because invalid!
---------------------------------------------- ----------------------------------
^/somepath(.*) /otherpath$1 [P] not supported, because silly!
---------------------------------------------- ----------------------------------
---------------------------------------------- ----------------------------------
(the [R] flag is redundant)
<
STRONG>Inside per-directory configuration for <
CODE>/somepath</
CODE><
BR>
<
CODE>RewriteBase /somepath</
CODE>)<
BR> for
<
TABLE BGCOLOR="#F0F0F0" CELLSPACING=0 CELLPADDING=5>
<
STRONG>Given Rule</
STRONG> <
STRONG>Resulting Substitution</
STRONG>
---------------------------------------------- ----------------------------------
^localpath(.*) otherpath$1 [P] not supported, because silly!
---------------------------------------------- ----------------------------------
^localpath(.*) /otherpath$1 [P] not supported, because silly!
---------------------------------------------- ----------------------------------
---------------------------------------------- ----------------------------------
(the [R] flag is redundant)
<
STRONG>Example:</
STRONG>
We want to rewrite URLs of the form
<
CODE>/</
CODE> <
EM>Language</
EM>
<
CODE>/~</
CODE> <
EM>Realname</
EM>
<
CODE>/.../</
CODE> <
EM>File</
EM>
<
CODE>/u/</
CODE> <
EM>Username</
EM>
<
CODE>/.../</
CODE> <
EM>File</
EM>
<
CODE>.</
CODE> <
EM>Language</
EM>
We take the rewrite mapfile from above and save it under
following lines to the Apache server configuration file:
RewriteRule ^/([^/]+)/~([^/]+)/(.*)$ /u/${real-to-user:$2|nobody}/$3.$1
<
H1><
A NAME="Miscelleneous">Miscellaneous</
A></
H1>
<
H2><
A NAME="EnvVar">Environment Variables</
A></
H2>
This module keeps track of two additional (non-standard)
CGI/
SSI environment
variables named <
CODE>SCRIPT_URL</
CODE> and <
CODE>SCRIPT_URI</
CODE>. These contain
the <
EM>logical</
EM> Web-view to the current resource, while the standard
CGI/
SSIvariables <
CODE>SCRIPT_NAME</
CODE> and <
CODE>SCRIPT_FILENAME</
CODE> contain the
<
EM>physical</
EM> System-view.
Notice: These variables hold the
URI/
URL <
EM>as they were initially
requested</
EM>, <
EM>
i.e.</
EM>, in a state <
EM>before</
EM> any rewriting. This is
important because the rewriting process is primarily used to rewrite logical
URLs to physical pathnames.
<
STRONG>Example:</
STRONG>
<
H2><
A NAME="Solutions">Practical Solutions</
A></
H2>
There is a comprehensive collection of practical solutions for URL-based
problems available by the author of mod_rewrite. Here you will find real-life
rulesets and additional information.
<
STRONG>Apache URL Rewriting Guide</
STRONG><
BR>
</
BLOCKQUOTE>
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