HTML pre-processor

The HTML pre-processor is used to provide dynamic information inside of a standard HTML (HyperText Markup Language) document. The pre-processor is a script, run by the WWW server, which takes the requested document as input and returns a standard HTML document for the server to send to the client. The script scans the input document for special pre-processor directives, which are replaced by dynamic data based upon the particular directive.

Directive syntax

The syntax follows closely that used by the NCSA httpd WWW server, although not as many directives are supported (yet). The directive is enclosed within an HTML comment and takes the form:
<!--#command [[tag="value"] ...]-->
The command and tag keywords are case insensitive. The tag value may or may not be case sensitive, depending upon the command/tag. Generally the effect of a command is to produce additional text to be inserted in the document.

Directive commands

BEGIN
The BEGIN directive marks the start of a region that may be selectively included with a part-qualified INCLUDE directive. A single BEGIN or END directive may specifiy multiple part names to begin or end at that point

ECHO
The ECHO command inserts special variables in the stream.
ACCESSES[;#]
Number of times document accessed, the access count is saved in the file www_root:[000000]accesses.dat.

ACCESSES_ORDINAL[;#]
Number of times document accessed with suffix(e.g. 1st)

DATE_LOCAL[=fmt]
Current system time

DOCUMENT_NAME
Filename (sans path) of current document

GETENV=symbol
Value of specified DCL symbol or logical

HW_NAME
Hardware model number

LAST_MODIFIED[=fmt]
Last-modified time of current document

SERVER_NAME
Hostname of current server

SERVER_VERSION
Server software version string

VMS_VERSION
Operating system version number

END
The END directive marks the end of a region started by a previous BEGIN directive (see BEGIN). A file may specify more than one region with matching BEGIN/END pairs.

FLASTMOD
The FLASTMOD command inserts the file modification date of a specified file at the current point in the document being pre-processed.

If the preprocessor executable was built using the DEC C compiler, you can follow the file="fname" or virtual="path" tag with and fmt="fmt-str" tag. If a format string is specified, the date is formatted using strftime() rather than ctime(). The specified format is used as the format string for a call to strftime()

FSIZE
The FSIZE command inserts the file size in bytes (as best as can be determined) of a specified file at the current point in the document being pre-processed.

INCLUDE
The INCLUDE command inserts the content of another document at the current point in the document being pre-processed. Optionally, you may specify an part tag and name and only the named regions (see BEGIN and END directives) in the file will be inserted.

Examples

Including a file
<!--#include file="open_hours.html"-->
<!--#include file="open_hours.html" part="holiday"-->
<!--#include virtual="/wasd_root/src/osu/admin/open_hours.html"-->
(file: This TEXT is actually from a separate file. )
(virt: This TEXT is actually from a separate file. )
(virt(rel): This TEXT is actually from a separate file. )

File attributes
<!--#fsize file="portrait.gif"-->
<!--#flastmod virtual="/wasd_root/src/osu/admin/open_hours.html" fmt="%I:%M:%S %p"-->
(Included size: 54 bytes, date: 13-Feb-2018 16:41:11)
(Alt. format lastmod: 04:41:11 PM)

Current document attributes
<!--#echo var="DOCUMENT_NAME"-->
<!--#echo var="LAST_MODIFIED[=fmt]"-->
<!--#echo var="ACCESSES"-->
<!--#echo var="ACCESSES_ORDINAL;5"-->
(document: WASD_ROOT:[src.osu]preproc.htmlx, date: 13-Feb-2018 16:41:11, 1,374th access)
(document: WASD_ROOT:[src.osu]preproc.htmlx, date: Tuesday, February 13, 2018 04:41:11 PM, 1,374 accesses)

Current time
<!--#echo var="DATE_LOCAL"--> (18-Jan-2019 14:27:20)
<!--#echo var="DATE_LOCAL=%B %d, %Y %I:%M:%S %p"--> (alt format: January 18, 2019 02:27:20 PM)

Miscellaneous echo vars
<!--#echo= var="GETENV=SYS$REM_ID"--> ([VARIABLE-DOES-NOT-EXIST!])
<!--#echo var="SERVER_NAME"-->
<!--#echo var="SERVER_VERSION"-->
<!--#echo var="VMS_VERSION"-->
<!--#echo var="HW_NAME"-->
(Host juhani.exdecfinland.org is a AlphaServer DS20 500 MHz running the HTTPd-WASD/11.1.1 OpenVMS/AXP SSL HTTP server under VMS V8.4 )

David Jones, Ohio State University