Apache HTTP Server Version 2.0
Description: | Server-parsed html documents (Server Side Includes) |
---|---|
Status: | Base |
Module Identifier: | include_module |
Source File: | mod_include.c |
Compatibility: | Implemented as an output filter since Apache 2.0 |
This module provides a filter which will process files before they are sent to the client. The processing is controlled by specially formatted SGML comments, referred to as elements. These elements allow conditional text, the inclusion of other files or programs, as well as the setting and printing of environment variables.
Server Side Includes are implemented by the INCLUDES
filter. If documents containing server-side include directives are given the extension .shtml, the following directives will make Apache parse them and assign the resulting document the mime type of text/html
:
AddType text/html .shtml
AddOutputFilter INCLUDES .shtml
The following directive must be given for the directories containing the shtml files (typically in a <Directory>
section, but this directive is also valid in .htaccess
files if AllowOverride
Options
is set):
Options +Includes
For backwards compatibility, the server-parsed
handler also activates the INCLUDES filter. As well, Apache will activate the INCLUDES filter for any document with mime type text/x-server-parsed-html
or text/x-server-parsed-html3
(and the resulting output will have the mime type text/html
).
For more information, see our Tutorial on Server Side Includes.
Files processed for server-side includes no longer accept requests with PATH_INFO
(trailing pathname information) by default. You can use the AcceptPathInfo
directive to configure the server to accept requests with PATH_INFO
.
The document is parsed as an HTML document, with special commands embedded as SGML comments. A command has the syntax:
<!--#element attribute=value attribute=value ... -->
The value will often be enclosed in double quotes, but single quotes ('
) and backticks (`
) are also possible. Many commands only allow a single attribute-value pair. Note that the comment terminator (-->
) should be preceded by whitespace to ensure that it isn't considered part of an SSI token. Note that the leading <!--#
is one token and may not contain any whitespaces.
The allowed elements are listed in the following table:
Element | Description |
---|---|
config |
configure output formats |
echo |
print variables |
exec |
execute external programs |
fsize |
print size of a file |
flastmod |
print last modification time of a file |
include |
include a file |
printenv |
print all available variables |
set |
set a value of a variable |
SSI elements may be defined by modules other than mod_include
. In fact, the exec
element is provided by mod_cgi
, and will only be available if this module is loaded.
This command controls various aspects of the parsing. The valid attributes are:
errmsg
SSIErrorMsg
directives.sizefmt
bytes
for a count in bytes, or abbrev
for a count in Kb or Mb as appropriate, for example a size of 1024 bytes will be printed as "1K".timefmt
strftime(3)
library routine when printing dates.This command prints one of the include variables, defined below. If the variable is unset, the result is determined by the SSIUndefinedEcho
directive. Any dates printed are subject to the currently configured timefmt
.
Attributes:
var
encoding
Specifies how Apache should encode special characters contained in the variable before outputting them. If set to none
, no encoding will be done. If set to url
, then URL encoding (also known as %-encoding; this is appropriate for use within URLs in links, etc.) will be performed. At the start of an echo
element, the default is set to entity
, resulting in entity encoding (which is appropriate in the context of a block-level HTML element, e.g. a paragraph of text). This can be changed by adding an encoding
attribute, which will remain in effect until the next encoding
attribute is encountered or the element ends, whichever comes first.
The encoding
attribute must precede the corresponding var
attribute to be effective, and only special characters as defined in the ISO-8859-1 character encoding will be encoded. This encoding process may not have the desired result if a different character encoding is in use.
The exec
command executes a given shell command or CGI script. It requires mod_cgi
to be present in the server. If Options
IncludesNOEXEC
is set, this command is completely disabled. The valid attributes are:
cgi
The value specifies a (%-encoded) URL-path to the CGI script. If the path does not begin with a slash (/), then it is taken to be relative to the current document. The document referenced by this path is invoked as a CGI script, even if the server would not normally recognize it as such. However, the directory containing the script must be enabled for CGI scripts (with ScriptAlias
or Options
ExecCGI
).
The CGI script is given the PATH_INFO
and query string (QUERY_STRING
) of the original request from the client; these cannot be specified in the URL path. The include variables will be available to the script in addition to the standard CGI environment.
<!--#exec cgi="/cgi-bin/example.cgi" -->
If the script returns a Location:
header instead of output, then this will be translated into an HTML anchor.
The include virtual
element should be used in preference to exec cgi
. In particular, if you need to pass additional arguments to a CGI program, using the query string, this cannot be done with exec cgi
, but can be done with include virtual
, as shown here:
<!--#include virtual="/cgi-bin/example.cgi?argument=value" -->
cmd
The server will execute the given string using /bin/sh
. The include variables are available to the command, in addition to the usual set of CGI variables.
The use of #include virtual
is almost always prefered to using either #exec cgi
or #exec cmd
. The former (#include virtual
) uses the standard Apache sub-request mechanism to include files or scripts. It is much better tested and maintained.
In addition, on some platforms, like Win32, and on unix when using suexec, you cannot pass arguments to a command in an exec
directive, or otherwise include spaces in the command. Thus, while the following will work under a non-suexec configuration on unix, it will not produce the desired result under Win32, or when running suexec:
<!--#exec cmd="perl /path/to/perlscript arg1 arg2" -->
This command prints the size of the specified file, subject to the sizefmt
format specification. Attributes:
file
virtual
This command prints the last modification date of the specified file, subject to the timefmt
format specification. The attributes are the same as for the fsize
command.
This command inserts the text of another document or file into the parsed file. Any included file is subject to the usual access control. If the directory containing the parsed file has Options IncludesNOEXEC
set, then only documents with a text MIME type (text/plain
, text/html
etc.) will be included. Otherwise CGI scripts are invoked as normal using the complete URL given in the command, including any query string.
An attribute defines the location of the document; the inclusion is done for each attribute given to the include command. The valid attributes are:
file
../
, nor can it be an absolute path. Therefore, you cannot include files that are outside of the document root, or above the current document in the directory structure. The virtual
attribute should always be used in preference to this one.virtual
The value is a (%-encoded) URL-path. The URL cannot contain a scheme or hostname, only a path and an optional query string. If it does not begin with a slash (/) then it is taken to be relative to the current document.
A URL is constructed from the attribute, and the output the server would return if the URL were accessed by the client is included in the parsed output. Thus included files can be nested.
If the specified URL is a CGI program, the program will be executed and its output inserted in place of the directive in the parsed file. You may include a query string in a CGI url:
<!--#include virtual="/cgi-bin/example.cgi?argument=value" -->
include virtual
should be used in preference to exec cgi
to include the output of CGI programs into an HTML document.
This prints out a listing of all existing variables and their values. Special characters are entity encoded (see the echo
element for details) before being output. There are no attributes.
<!--#printenv -->
This sets the value of a variable. Attributes:
var
value
<!--#set var="category" value="help" -->
In addition to the variables in the standard CGI environment, these are available for the echo
command, for if
and elif
, and to any program invoked by the document.
DATE_GMT
DATE_LOCAL
DOCUMENT_NAME
DOCUMENT_URI
LAST_MODIFIED
QUERY_STRING_UNESCAPED
&
etc. are preceded by backslashes).Variable substitution is done within quoted strings in most cases where they may reasonably occur as an argument to an SSI directive. This includes the config
, exec
, flastmod
, fsize
, include
, echo
, and set
directives, as well as the arguments to conditional operators. You can insert a literal dollar sign into the string using backslash quoting:
<!--#if expr="$a = \$test" -->
If a variable reference needs to be substituted in the middle of a character sequence that might otherwise be considered a valid identifier in its own right, it can be disambiguated by enclosing the reference in braces, a la shell substitution:
<!--#set var="Zed" value="${REMOTE_HOST}_${REQUEST_METHOD}" -->
This will result in the Zed
variable being set to "X_Y
" if REMOTE_HOST
is "X
" and REQUEST_METHOD
is "Y
".
The below example will print "in foo" if the DOCUMENT_URI
is /foo/file.html
, "in bar" if it is /bar/file.html
and "in neither" otherwise:
<!--#if expr='"$DOCUMENT_URI" = "/foo/file.html"' -->
in foo
<!--#elif expr='"$DOCUMENT_URI" = "/bar/file.html"' -->
in bar
<!--#else -->
in neither
<!--#endif -->
The basic flow control elements are:
<!--#if expr="test_condition" -->
<!--#elif expr="test_condition" -->
<!--#else -->
<!--#endif -->
The if
element works like an if statement in a programming language. The test condition is evaluated and if the result is true, then the text until the next elif
, else
or endif
element is included in the output stream.
The elif
or else
statements are be used to put text into the output stream if the original test_condition was false. These elements are optional.
The endif
element ends the if
element and is required.
test_condition is one of the following:
string
string1 = string2
string1 != string2
Compare string1 with string2. If string2 has the form /string2/
then it is treated as a regular expression. Regular expressions are implemented by the PCRE engine and have the same syntax as those in perl 5.
If you are matching positive (=
), you can capture grouped parts of the regular expression. The captured parts are stored in the special variables $1
.. $9
.
<!--#if expr="$QUERY_STRING = /^sid=([a-zA-Z0-9]+)/" -->
<!--#set var="session" value="$1" -->
<!--#endif -->
string1 < string2
string1 <= string2
string1 > string2
string1 >= string2
strcmp(3)
). Therefore the string "100" is less than "20".( test_condition )
! test_condition
test_condition1 && test_condition2
test_condition1 || test_condition2
"=
" and "!=
" bind more tightly than "&&
" and "||
". "!
" binds most tightly. Thus, the following are equivalent:
<!--#if expr="$a = test1 && $b = test2" -->
<!--#if expr="($a = test1) && ($b = test2)" -->
The boolean operators &&
and ||
share the same priority. So if you want to bind such an operator more tightly, you should use parentheses.
Anything that's not recognized as a variable or an operator is treated as a string. Strings can also be quoted: 'string'
. Unquoted strings can't contain whitespace (blanks and tabs) because it is used to separate tokens such as variables. If multiple strings are found in a row, they are concatenated using blanks. So,
string1 string2
results in string1 string2
and
'string1 string2'
results in string1 string2
.
Description: | String that ends an include element |
---|---|
Syntax: | SSIEndTag tag |
Default: | SSIEndTag "-->" |
Context: | server config, virtual host |
Status: | Base |
Module: | mod_include |
Compatibility: | Available in version 2.0.30 and later. |
This directive changes the string that mod_include
looks for to mark the end of an include element.
SSIEndTag "%>"
Description: | Error message displayed when there is an SSI error |
---|---|
Syntax: | SSIErrorMsg message |
Default: | SSIErrorMsg "[an error occurred while processing this directive]" |
Context: | server config, virtual host, directory, .htaccess |
Override: | All |
Status: | Base |
Module: | mod_include |
Compatibility: | Available in version 2.0.30 and later. |
The SSIErrorMsg
directive changes the error message displayed when mod_include
encounters an error. For production servers you may consider changing the default error message to "<!-- Error -->"
so that the message is not presented to the user.
This directive has the same effect as the <!--#config errmsg=message -->
element.
SSIErrorMsg "<!-- Error -->"
Description: | String that starts an include element |
---|---|
Syntax: | SSIStartTag tag |
Default: | SSIStartTag "<!--#" |
Context: | server config, virtual host |
Status: | Base |
Module: | mod_include |
Compatibility: | Available in version 2.0.30 and later. |
This directive changes the string that mod_include
looks for to mark an include element to process.
You may want to use this option if you have 2 servers parsing the output of a file each processing different commands (possibly at different times).
SSIStartTag "<%"
SSIEndTag "%>"
The example given above, which also specifies a matching SSIEndTag
, will allow you to use SSI directives as shown in the example below:
<%printenv %>
Description: | Configures the format in which date strings are displayed |
---|---|
Syntax: | SSITimeFormat formatstring |
Default: | SSITimeFormat "%A, %d-%b-%Y %H:%M:%S %Z" |
Context: | server config, virtual host, directory, .htaccess |
Override: | All |
Status: | Base |
Module: | mod_include |
Compatibility: | Available in version 2.0.30 and later. |
This directive changes the format in which date strings are displayed when echoing DATE
environment variables. The formatstring is as in strftime(3)
from the C standard library.
This directive has the same effect as the <!--#config timefmt=formatstring -->
element.
SSITimeFormat "%R, %B %d, %Y"
The above directive would cause times to be displayed in the format "22:26, June 14, 2002".
Description: | String displayed when an unset variable is echoed |
---|---|
Syntax: | SSIUndefinedEcho string |
Default: | SSIUndefinedEcho "(none)" |
Context: | server config, virtual host |
Status: | Base |
Module: | mod_include |
Compatibility: | Available in version 2.0.34 and later. |
This directive changes the string that mod_include
displays when a variable is not set and "echoed".
SSIUndefinedEcho "<!-- undef -->"
Description: | Parse SSI directives in files with the execute bit set |
---|---|
Syntax: | XBitHack on|off|full |
Default: | XBitHack off |
Context: | server config, virtual host, directory, .htaccess |
Override: | Options |
Status: | Base |
Module: | mod_include |
The XBitHack
directive controls the parsing of ordinary html documents. This directive only affects files associated with the MIME type text/html
. XBitHack
can take on the following values:
off
on
text/html
file that has the user-execute bit set will be treated as a server-parsed html document.full
on
but also test the group-execute bit. If it is set, then set the Last-modified
date of the returned file to be the last modified time of the file. If it is not set, then no last-modified date is sent. Setting this bit allows clients and proxies to cache the result of the request.
You would not want to use the full option, unless you assure the group-execute bit is unset for every SSI script which might #include
a CGI or otherwise produces different output on each hit (or could potentially change on subsequent requests).