Apache HTTP Server Version 2.3
Available Languages: en
Historically, there are several syntax variants for expressions used to express a condition in the different modules of the Apache HTTP Server. There is some ongoing effort to only use a single variant, called ap_expr, for all configuration directives. This document describes the ap_expr expression parser.
expr ::= "true" | "false" | "!" expr | expr "&&" expr | expr "||" expr | "(" expr ")" | comp comp ::= stringcomp | integercomp | unaryop word | word binaryop word | word "in" "{" wordlist "}" | word "in" listfunction | word "=~" regex | word "!~" regex stringcomp ::= word "==" word | word "!=" word | word "<" word | word "<=" word | word ">" word | word ">=" word integercomp ::= word "-eq" word | word "eq" word | word "-ne" word | word "ne" word | word "-lt" word | word "lt" word | word "-le" word | word "le" word | word "-gt" word | word "gt" word | word "-ge" word | word "ge" word wordlist ::= word | wordlist "," word word ::= word "." word | digit | "'" string "'" | """ string """ | variable | rebackref | function string ::= stringpart | string stringpart stringpart ::= cstring | variable | rebackref cstring ::= ... digit ::= [0-9]+ variable ::= "%{" varname "}" | "%{" funcname ":" funcargs "}" rebackref ::= "$" [0-9] function ::= funcname "(" word ")" listfunction ::= listfuncname "(" word ")"
The expression parser provides a number of variables of the form
%{HTTP_HOST}
. Note that the value of a variable may depend
on the phase of the request processing in which it is evaluated. For
example, an expression used in an <If >
directive is evaluated before authentication is done. Therefore,
%{REMOTE_USER}
will not be set in this case.
The following variables provide the values of the named HTTP request
headers. The values of other headers can be obtained witht the
req
function.
Name |
---|
HTTP_ACCEPT |
HTTP_FORWARDED |
HTTP_HOST |
HTTP_PROXY_CONNECTION |
HTTP_REFERER |
HTTP_USER_AGENT |
Other request related variables
Name | Description |
---|---|
REQUEST_METHOD |
The HTTP method of the incoming request (e.g.
GET |
REQUEST_SCHEME |
The scheme part of the request's URI |
REQUEST_URI |
The URI of the request |
REQUEST_FILENAME |
|
SCRIPT_FILENAME |
Same as REQUEST_FILENAME |
PATH_INFO |
|
QUERY_STRING |
The query string of the current request |
IS_SUBREQ |
"true " if the current request is a subrequest,
"false " otherwise |
THE_REQUEST |
The complete request line (e.g.,
"GET /index.html HTTP/1.1 ") |
REMOTE_ADDR |
The IP address of the remote host |
REMOTE_HOST |
The host name of the remote host |
REMOTE_USER |
The name of the authenticated user (if any) |
REMOTE_IDENT |
The user name set by mod_ident |
SERVER_NAME |
The ServerName of
the current vhost |
SERVER_PORT |
The server port of the current vhost, see
ServerName |
SERVER_ADMIN |
The ServerAdmin of
the current vhost |
SERVER_PROTOCOL |
The protocol used by the request |
DOCUMENT_ROOT |
The DocumentRoot of
the current vhost |
AUTH_TYPE |
The configured AuthType
(e.g. "basic ") |
CONTENT_TYPE |
The content type of the response |
HANDLER |
The name of the handler creating the response |
HTTPS |
"on " if the request uses https,
"off " otherwise |
IPV6 |
"on " if the connection uses IPv6,
"off " otherwise |
REQUEST_LOG_ID |
The error log id of the request (see
ErrorLogFormat ) |
CONN_LOG_ID |
The error log id of the connection (see
ErrorLogFormat ) |
Misc variables
Name | Description |
---|---|
TIME_YEAR |
The current year (e.g. 2010 ) |
TIME_MON |
The current month (1 , ..., 12 ) |
TIME_DAY |
The current day of the month |
TIME_HOUR |
The hour part of the current time
(0 , ..., 23 ) |
TIME_MIN |
The minute part of the current time |
TIME_SEC |
The second part of the current time |
TIME_WDAY |
The day of the week (starting with 0
for Sunday) |
TIME |
The date and time in the format 20101231235959 |
SERVER_SOFTWARE |
The server version string |
API_VERSION |
The date of the API version (module magic number) |
Some modules register additional variables, see e.g. mod_ssl
.
With the exception of some built-in comparison operators, binary
operators have the form "-[a-zA-Z][a-zA-Z0-9_]+
", i.e. a
minus and at least two characters. The name is not case sensitive.
Modules may register additional binary operators.
Name | Alternative | Description |
---|---|---|
== |
= |
String equality |
!= |
String inequality | |
< |
String less than | |
<= |
String less than or equal | |
> |
String greater than | |
>= |
String greater than or equal | |
-eq |
eq |
Integer equality |
-ne |
ne |
Integer inequality |
-lt |
lt |
Integer less than |
-le |
le |
Integer less than or equal |
-gt |
gt |
Integer greater than |
-ge |
ge |
Integer greater than or equal |
Name | Description |
---|---|
-ipmatch |
IP address matches address/netmask |
-strmatch |
left string matches pattern given by right string (containing wildcards *, ?, []) |
-strcmatch |
same as -strmatch , but case insensitive |
-fnmatch |
same as -strmatch , but slashes are not matched by
wildcards |
Unary operators have the form "-[a-zA-Z]
", i.e. a
minus and one character. The name is case sensitive.
Modules may register additional unary operators.
Name | Description |
---|---|
-n |
String is not empty |
-z |
String is empty |
-R |
Same as "%{REMOTE_ADDR} -ipmatch ... ", but more efficient
|
Normal string-valued functions take one string as argument and return a string. Functions names are not case sensitive. Modules may register additional functions.
Name | Description |
---|---|
req , http |
Get HTTP request header |
resp |
Get HTTP response header |
reqenv |
Lookup request environment variable |
osenv |
Lookup operating system environment variable |
note |
Lookup request note |
env |
Return first match of note , reqenv ,
osenv |
tolower |
Convert string to lower case |
toupper |
Convert string to uppser case |
escape |
Escape special characters in %hex encoding |
unescape |
Unescape %hex encoded string, leaving URL-special characters encoded (XXX: describe better) |
file |
Read contents from a file |
In addition to string-valued functions, there are also list-valued functions which
take one string as argument and return a wordlist, i.e. a list of strings. The wordlist
can be used with the special -in
operator.
Functions names are not case sensitive.
Modules may register additional functions.
There are no built-in list-valued functions. mod_ssl
provides PeerExtList
. See the description of
SSLRequire
for details
(but PeerExtList
is also usable outside
of SSLRequire
).
Name | Alternative | Description |
---|---|---|
-in |
in |
string contained in string list |
/regexp/ |
m#regexp# |
Regular expression (the second form allows different delimiters than /) |
/regexp/i |
m#regexp#i |
Case insensitive regular expression |
$0 ... $9 |
Regular expression backreferences |
The strings $0
... $9
allow to reference
the capture groups form a previously executed, successfully
matching regular expressions. They can normally only be used in the
same expression as the matching regex, but some modules allow special
uses.
Available Languages: en