Flexible variable declaration and propagation is the heart of the FileWiki system. While some variables affect the FileWiki system, they are basically used as input to the template processor. Every page merges its vars from various locations (see "Propagation" below).


Variables are declared in a simple "key=value" or "key value" format. Variable expansion is performed in occurrence of either $myvar, ${myvar}, or ${{myvar}} (see "Variable Expansion" below).

  • Lines starting with '#' (hash) are ignored
  • Trailing whitespaces are cut off
  • Double quotes are removed at beginning and end of value
  • Keys starting with '+' (plus) are appended to an array
  • Values starting with '\\' are multi-line, with '\\' on last line


title=FileWiki Documentation

This results in both "title" and "menu" variables to have the value "Summary". This is equivalent to:

title  "FileWiki Documentation"
menu   $title


tree vars

Parsed from file "tree.vars" in every directory.

tree.vars are propagated to dir.vars and page.vars, and are persistent within sub-directories. tree.vars in sub-directories supersede the tree.vars of the parent directory.

dir vars

Parsed from file "dir.vars" in every directory.

Used for the directory node. Consider the dir.vars as metadata for the directory they are located in. dir.vars are not propagated, but are accessible on a page via the DIR variable.

page vars

Parsed from file "<source_file>.vars".

page.vars supersede the tree.vars for a page. Consider the page.vars as metadata for a page. Every source page can have page.vars.

nested vars

Parsed from within the source files (if supported by the plugin enabled).

Nested vars supersede the page.vars. FileWiki starts to parse nested variables from the source file after it first encounters a line starting with <filewiki_vars> or [filewiki_vars], up to </filewiki_vars> or [/filewiki_vars].

Note that the nested.vars are stripped off the source file when processing the input filters.


Page text...


Page text...

As a special feature for pages which are also parsed outside FileWiki (e.g. perl modules), a "un-comment" character is defined by the first character preceding <filewiki_vars>.

Example (equivalent to example above):

File text (e.g. Perl code)...
File text...

In this example, the "un-comment" character is set to '#', and all variables are parsed.

Variable Expansion

Early Expansion

Variable early expansion happens directly at the time the key/value line is read from disk. This is the common case for propagating variables through directories.

Early expansion for expressions is accepted in form:

  • $KEY: expand to the value of variable KEY, or "" if KEY is not found.

  • ${KEY_EXPR}: expression in form ${KEY0[|KEY1...]}, returning the first valid value from KEYn.

  • ${KEY_EXPR[/MATCH/REPLACE]}: performs a regular expression s/MATCH/REPLACE/ on the value of KEY_EXPR.

  • ${KEY_EXPR[//MATCH/REPLACE]}: performs a global regular expression s/MATCH/REPLACE/g on the value of KEY_EXPR.


OUTPUT_DIR   /tmp/filewiki/htdocs
stylesheet   $URI_PREFIX/filewiki.css
debug_name   XXX${NAME}XXX

Late Expansion

Variable late expansion happens after all variables are read by a page or directory node. This is particulary useful if you want to define a variable derived from internal variables set by plugins. Note that setting system variables on late-expansion time might lead to undefined behaviour, as the plugins might rely on these variables before late-expansion happens.

Late expansion has the same semantics as early expansion, except that double brackets are used: ${{...}}


commit_msg   This page was committed by: ${{GIT_AUTHOR_NAME}}.
date         ${{NAME/^(\d\d\d\d-\d\d-\d\d)-/$1}}
title        ${{NAME/^\d\d\d\d-\d\d-\d\d-(.*)/$1}}

For files named like "yyyy-mm-dd-myfile", this sets a variables date and title from the source file name.

Logical Expressions

Expressions in form $((...)) are executed at late expansion time.

Logical expressions are accepted in form:

  • $(( [[!]CONDITION:] EXPR0 || EXPR1 || ... )): expands to expression EXPR0, or to EXPR1..., whichever expression resolves to true first. Expands to an empty string if CONDITION resolves to false.


date    $(( ${{EXIF_TIME}} || ${{NAME/^(\d\d\d\d-\d\d-\d\d)-/$1}} || ${{MTIME}} ))
title   $((IS_DIR: ${{NAME/^\d\d\d\d-\d\d-\d\d-/}} ))

This sets variable date from EXIF_TIME, falling back to the date prefix of NAME, finally falling back to MTIME. Sets variable title to the title portion of NAME, but only if IS_DIR variable is set (i.e. only for a directory node).