Mod_Rewrite Variables Cheatsheet

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Mod_Rewrite Variables Cheatsheet

We’ve figured out what mod_rewrite variables look like so we can create rewriterules and condition patterns based on the actual value. This cheatsheet is where we’ll lay them all out for quick reference. This cheatsheet changed my life.

mod_rewrite Variable Value Cheat-Sheet

API_VERSION

20020903:12

AUTH_TYPE

Digest

CACHE_CONTROL

max-age=0

CONNECTION

keep-alive

CONTENT_LENGTH

(null)

CONTENT_TYPE

(null)

DOCUMENT_ROOT

/home/webroot/askapache.com

HOST

www.askapache.com

HTTPS

off

HTTP_ACCEPT

text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8

HTTP_COOKIE

__qca=1176541205adf28-5553185; ASKAPACHEID=fdadfa4f33e62a878468; __utmc=1df3893

HTTP_HOST

www.askapache.com

HTTP_REFERER

http://www.askapache.com/pro/mod_rewrite/catch.php?k=i

HTTP_USER_AGENT

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9) Firefox/3.0.1

IS_SUBREQ

false

KEEP_ALIVE

300

PATH

/bin:/usr/bin:/sbin:/usr/sbin

QUERY_STRING

k=i

REMOTE_ADDR

22.162.134.211

REMOTE_HOST

22.162.134.211

REMOTE_PORT

4220

REMOTE_USER

askapache

REQUEST_FILENAME

/home/webroot/askapache.com/pro/mod_rewrite/index.php

REQUEST_METHOD

GET

REQUEST_PROTOCOL

HTTP/1.1

REQUEST_URI

/pro/mod_rewrite/index.php

SCRIPT_FILENAME

/home/webroot/askapache.com/pro/mod_rewrite/index.php

SCRIPT_GROUP

daemong

SCRIPT_URI

http://www.askapache.com/pro/mod_rewrite/index.php

SCRIPT_URL

/pro/mod_rewrite/index.php

SCRIPT_USER

askapache

SERVER_ADDR

208.113.134.190

SERVER_ADMIN

webmaster@askapache.com

SERVER_NAME

www.askapache.com

SERVER_PORT

80

SERVER_PROTOCOL

HTTP/1.1

SERVER_SOFTWARE

Apache/2.0.61 (Unix) PHP/5.5 OpenSSL/0.9.7e

THE_REQUEST

GET /pro/mod_rewrite/index.php?k=i HTTP/1.1

TIME

20080915152142

TIME_DAY

15

TIME_HOUR

15

TIME_MIN

21

TIME_MON

09

TIME_SEC

42

TIME_WDAY

1

TIME_YEAR

2008

UNIQUE_ID

qOr5tEBvcm8AAE-VoiUAAAAQ

This article is meant to prepare us for the advanced mod_rewrite examples that are soon to be published. The upcoming article is going to be examples using mod_rewrite to achieve some crazy stuff… Here the focus is on identifying mod_rewrite variables and defining the limits of the module by checking the mod_rewrite source code.

For a broader mod_rewrite cheat sheet, check this printable cheat sheet.

Directives in Mod_Rewrite

RewriteEngine

RewriteEngine on|off

On or Off to enable or disable (default) the whole rewriting engine

RewriteOptions

RewriteOptions Options

List of option strings to set

RewriteBase

RewriteBase URL-path

the base URL of the per-directory context

RewriteCond

RewriteCond TestString CondPattern

an input string and a to be applied regexp-pattern

RewriteRule

RewriteRule Pattern Substitution [flags]

an URL-applied regexp-pattern and a substitution URL

RewriteMap

RewriteMap MapName MapType:MapSource

a mapname and a filename

RewriteLock

RewriteLock file-path

the filename of a lockfile used for inter-process synchronization

RewriteLog

RewriteLog file-path

the filename of the rewriting logfile

RewriteLogLevel

RewriteLogLevel Level

the level of the rewriting logfile verbosity (0=none, 1=std, .., 9=max)

RewriteRule Flags

C

Using the [Chain], or [C] flag, allows you to indicate that several rules should be chained together as a single logical transation. This is usually used when a transformation is sufficiently complicated to warrant breaking into several smaller steps.

E

'env|E=VAR:VAL' (set environment variable)

RewriteRule (root|cmd)\.exe – [E=worm:nimda]

F

'forbidden|F' (force URL to be forbidden)

G

'gone|G' (force URL to be gone)

H

'handler|H=Content-handler' (force Content handler)

L

'last|L' (last rule)

N

'next|N' (next round)

NC

'nocase|NC' (no case)

NE

'noescape|NE' (no URI escaping of output)

NS

'nosubreq|NS' (not for internal sub-requests)

P

'proxy|P' (force proxy)

PT

'passthrough|PT' (pass through to next handler)

QSA

'qsappend|QSA' (query string append)

R

'redirect|R  [=code]' (force redirect)

S

'skip|S=num' (skip next rule(s))

This flag forces the rewriting engine to skip the next num rules in sequence, if the current rule matches. Use this to make pseudo if-then-else constructs: The last rule of the then-clause becomes skip=N, where N is the number of rules in the else-clause. (This is not the same as the ‘chain|C’ flag!)

T

'type|T=MIME-type' (force MIME type)

Force the MIME-type of the target file to be MIME-type. This can be used to set up the content-type based on some conditions. For example, the following snippet allows .php files to be displayed by mod_php if they are called with the .phps extension:

Rules and Conditions Processing Order

1. The Pattern of the RewriteRule (^/.*$) is checked first.
2. If the pattern matches, then the RewriteCond’s are checked.
3. If the RewriteConditions also match, the RewriteRule is applied.

RewriteRule Special Variables

1. ENV_
2. SSL_
3. HTTP_
4. LA-U_
5. LA-F_

RewriteCond Tests

• f – FILE_EXISTS
• s – FILE_SIZE
• l – FILE_LINK
• d – FILE_DIR
• x – FILE_XBIT
• U – LU_URL
• F – LU_FILE
• > – STR_GT
• < – STR_LT
• = – STR_EQ

Special Rewrite Redirects

1. “permanent” – HTTP_MOVED_PERMANENTLY
2. “temp” – HTTP_MOVED_TEMPORARILY
3. “seeother” – HTTP_SEE_OTHER
4. digit

Recognized by Mod_Rewrite

1. ajp://
2. balancer://
3. ftp://
4. gopher://
5. http://
6. https://
7. ldap://
8. mailto:
9. news:
10. nntp://

Mod_Rewrite Variables, from Source

• TIME – %04d%02d%02d%02d%02d%02d
• HTTPS – flag ? "on" : "off"
• TIME_DAY
• TIME_SEC
• TIME_MIN
• TIME_HOUR
• TIME_MON
• TIME_WDAY
• TIME_YEAR
• IS_SUBREQ – (main ? "true" : "false");
• PATH_INFO – path_info;
• AUTH_TYPE – ap_auth_type;
• HTTP_HOST – lookup_header("Host", ctx);
• SERVER_NAME – ap_get_server_name(r);
• REMOTE_ADDR – connection->remote_ip;
• SERVER_ADDR – connection->local_ip;
• HTTP_ACCEPT – lookup_header("Accept", ctx);
• THE_REQUEST – the_request;
• API_VERSION – "%d:%d",MODULE_MAGIC_NUMBER_MAJOR,MODULE_MAGIC_NUMBER_MINOR);
• HTTP_COOKIE – lookup_header("Cookie", ctx);
• SERVER_PORT – ap_get_server_port(r);
• REMOTE_HOST
• REMOTE_NAME, NULL);
• REMOTE_PORT - r->connection->remote_addr->port
• REMOTE_USER - user;
• SCRIPT_USER - "";
• APR_FINFO_USER
• REQUEST_URI - uri;
• SCRIPT_GROUP - "";
• REMOTE_IDENT - ap_get_remote_logname(r);
• HTTP_REFERER - lookup_header("Referer", ctx);
• QUERY_STRING - args;
• SERVER_ADMIN - server->server_admin;
• DOCUMENT_ROOT - ap_document_root(r);
• HTTP_FORWARDED - lookup_header("Forwarded", ctx);
• REQUEST_METHOD - method;
• HTTP_USER_AGENT - lookup_header("User-Agent", ctx);
• SCRIPT_FILENAME - same as request_filename
• REQUEST_FILENAME - same as script_filename
• SERVER_PROTOCOL - protocol
• SERVER_SOFTWARE - ap_get_server_banner();
• HTTP_PROXY_CONNECTION - lookup_header("Proxy-Connection", ctx);

REGEX Rewrite Guides

• Mod_Rewrite: Flags, Rules, Conditions, Tutorial and Variables
• Using Regular Expressions
• RewriteRule (mod_rewrite) guide

Mod_Rewrite Terms and Definitions

pattern

the RegExp pattern string

regexp

the RegExp pattern compilation

flags

Flags which control the substitution

forced_mimetype

forced MIME type of substitution

forced_handler

forced content handler of subst.

forced_responsecode

forced HTTP response status

env

added environment variables

cookie

added cookies

skip

number of next rules to skip

state

the RewriteEngine state

options

the RewriteOption state

rewritelogfile

the RewriteLog filename

rewritelogfp

the RewriteLog open filepointer

rewritelog: level

the RewriteLog level of verbosity

rewritemaps

the RewriteMap entries

rewriteconds

the RewriteCond entries (temp.)

rewriterules

the RewriteRule entries

directory

the directory where it applies

baseurl

the base-URL where it applies

Mod_Rewrite Errors

• Options FollowSymLinks or SymLinksIfOwnerMatch is off which implies that RewriteRule directive is forbidden: %s
• RewriteCond: bad argument line
• RewriteCond: NoCase option for non-regex pattern %s is not supported and will be ignored.
• RewriteCond: cannot compile regular expression
• RewriteRule: invalid HTTP response code %s for flag R
• RewriteRule: unknown flag
• RewriteRule: cannot compile regular expression
• RewriteOptions: MaxRedirects option has been removed in favor of the global LimitInternalRecursion directive and will be ignored.
• RewriteOptions: unknown option
• RewriteMap: bad path to txt map:
• RewriteMap: bad path to rnd map:
• RewriteMap: bad map:
• RewriteMap: bad path to dbm map:
• RewriteMap: dbm type
• RewriteMap: bad path to prg map:
• RewriteMap: internal map not found:
• RewriteMap: bad path to txt map:
• RewriteMap: file for map not found:
• Invalid RewriteLock path
• RewriteBase: only valid in per-directory config files
• RewriteBase: empty URL not allowed
• RewriteBase: argument is not a valid URL
• RewriteCond: bad flag delimiters
• RewriteCond: unknown flag
• RewriteLog and RewriteLogLevel are not supported by this build of mod_rewrite because it was compiled using the -DREWRITELOG_DISABLED compiler option. You have to recompile mod_rewrite WITHOUT this option in order to use the rewrite log.
• mod_rewrite: Invalid RewriteLog path %s
• mod_rewrite: could not open reliable pipe to RewriteLog filter %s
• mod_rewrite: Invalid RewriteLog path %s
• mod_rewrite: could not open RewriteLog file %s
• mod_rewrite: Running external rewrite maps without defining a RewriteLock is DANGEROUS!
• mod_rewrite: could not start RewriteMap program %s
• mod_rewrite: cant access text RewriteMap file %s
• mod_rewrite: cant access DBM RewriteMap file %s
• mod_rewrite: Parent could not create RewriteLock file %s
• mod_rewrite: Parent could not set permissions on RewriteLock check User and Group directives
• mod_rewrite: could not create rewrite_log_lock
• mod_rewrite: Could not set permissions on rewrite_log_lock check User and Group directives
• mod_rewrite: could not init rewrite_mapr_lock_acquire in child
• mod_rewrite: could not init rewrite log lock in child
• mod_rewrite: could not init map cache in child
• split uri=%s -> uri=%s, args=%s
• reduce %s -> %s
• strip matching prefix: %s -> %s
• add subst prefix: %s -> %s
• cant open RewriteMap file, see error log
• cache lookup FAILED, forcing new map lookup
• map lookup FAILED: map=%s[txt] key=%s
• map lookup OK: map=%s[txt] key=%s -> val=%s
• cache lookup OK: map=%s[txt] key=%s -> val=%s
• randomly chosen the subvalue `%s
• cant open DBM RewriteMap file, see error log
• cache lookup FAILED, forcing new map lookup
• map lookup FAILED: map=%s[dbm] key=%s
• map lookup OK: map=%s[dbm] key=%s -> val=%s
• cache lookup OK: map=%s[dbm] key=%s -> val=%s
• map lookup FAILED: map=%s key=%s
• map lookup OK: map=%s key=%s -> val=%s
• map lookup FAILED: map=%s key=%s
• map lookup OK: map=%s key=%s -> val=%s
• lookahead: path=%s var=%s -> val=%s
• lookahead: path=%s var=%s -> val=%s
• RESULT=%s
• escaping backreference %s to %s
• setting env variable %s to %s
• setting cookie %s, cookie
• skipping already set cookie %s
• RewriteCond URI (-U) check: path=%s -> status=%d
• RewriteCond file (-F) check: path=%s -> file=%s status=%d
• RewriteCond: input=%s pattern=%s%s%s%s => %s
• remember %s to have MIME-type %s
• remember %s to have Content-handler %s
• add path info postfix: %s -> %s%s
• strip per-dir prefix: %s -> %s
• applying pattern %s to uri %s
• rewrite %s -> %s, ctx->uri
• forcing responsecode %d for %s
• add per-dir prefix: %s -> %s%s
• forcing proxy-throughput with %s
• explicitly forcing redirect with %s
• implicitly forcing redirect (rc=%d) with %s
• forcing %s to get passed through to next API URI-to-filename handler
• init rewrite engine with requested uri %s
• go-ahead with proxy request %s [OK]
• dconf->directory,trying to replace prefix %s with %s
• escaping %s for redirect
• redirect to %s [REDIRECT/%d]
• initial URL equal rewritten URL: %s [IGNORING REWRITE]
• dconf->directory, trying to replace prefix %s with %s
• strip document_root prefix: %s -> %s
• internal redirect with %s [INTERNAL REDIRECT]
• pass through %s
• force filename %s to have MIME-type %s
• force filename %s to have the Content-handler %s,
• init rewrite engine with requested uri %s
• init rewrite engine with passed filename %s. Original uri = %s
• uri already rewritten. Status %s, Uri %s, %s
• attempt to make remote request from mod_rewrite without proxy enabled: %s
• go-ahead with proxy request %s [OK]
• escaping %s for redirect
• redirect to %s [REDIRECT/%d]
• local path result: %s
• prefixing with document_root of %s FAILED
• prefixed with document_root to %s
• go-ahead with %s [OK]
• pass through %s

URL Rewriting Module

This module uses a rule-based rewriting engine (based on a regular-expression parser) to rewrite requested URLs on the fly.

It supports an unlimited number of additional rule conditions (which can operate on a lot of variables, even on HTTP headers) for granular matching and even external database lookups (either via plain text tables, DBM hash files or even external processes) for advanced URL substitution.

It operates on the full URLs (including the PATH_INFO part) both in per-server context (httpd.conf) and per-dir context (.htaccess) and even can generate QUERY_STRING parts on result. The rewriting result finally can lead to internal subprocessing, external request redirection or even to internal proxy throughput.

This module was originally written in April 1996 and gifted exclusively to the The Apache Software Foundation in July 1997 by

Ralf S. Engelschall
rse [at] engenschall.com

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