Config File Syntax

The boxes config file is a succession of box design definitions.

Its character encoding is ASCII.

Boxes config files are case insensitive, i.e. upper/lower case does not matter.

Box Design

BOX design_name
END design_name

Every box design definition must have at least a SHAPE block, an ELASTIC list, and a SAMPLE block.


Everything following a pound sign (#) is considered a comment, as long as the pound sign isn’t part of a string or something.

Sample Block


This is the box image used for the list of available designs. The reason why an image is not simply generated is that this way, the box can be shown in an environment in which it might actually be used, e.g. with some C code around (see the boxes config file for many examples).

The ENDS statement must stand on a line of its own, although it may be indented. Such a line cannot occur as part of the sample itself.
The SAMPLE block is a required entry in every box design definition.

Shapes Block

    shape_name (string_list)
    shape_name (string_list)

shape_name may be one of nw, nnw, n, nne, ne, ene, e, ese, se, sse, s, ssw, sw, wsw, w, or wnw, corresponding to the figure shown earlier. The string_list represents the shape itself, line by line. Note that all lines must have equal length. Add extra spaces if necessary. Not also that double quotes (") which appear as part of a string must be escaped by a preceding backslash, so as not to terminate the string early. Consequently, all occurrences of backslashes must also be escaped by adding additional backslashes. The recommended process for creating a string is thus:

  1. Type in the string as you think it should look.
  2. Make your editor double all backslashes within the string.
  3. Escape all double quotes within the string by adding more backslashes.

In Vim, for example, this can be achieved by marking the block, and then typing:


Here are a few examples of valid entries in a SHAPE block:

ne ("+++", "+ +", "+++")
SSE ("///", "\\\\\\")
ene ()
s ("\"")

The delimiter statement can be used to redefine the string delimiting character and the escape character, thus eliminating the above backslash problem. The SHAPE block is a required entry in every box design definition.

Elastic List

ELASTIC (shape_name, shape_name, ...)

Simply lists the shapes which are elastic. Elastic shapes are repeated so that the box can grow and shrink to meet its requested size. Corner shapes may not be elastic. Naturally, there must always be at least one elastic shape per box side. No two neighboring shapes may be elastic. A typical ELASTIC entry would look like this:

elastic (n, e, s, w)

The elastic list is a required entry in every box design definition.

Padding Block

    side_or_group_of_sides value
    side_or_group_of_sides value

Defines the default padding area. Possible values for side_or_group_of_sides are all, horizontal, vertical, top, left, right, or bottom. A padding block may contain an arbitrary number of entries. Entries are read from top to bottom, so that later entries overwrite earlier entries. In the following example:

padding {
    vertical 3
    horiz 2
    left 4

the padding is set to 3 blank lines above the text, 2 spaces to the right of the text, 3 blank lines below the text, and 4 spaces to the left of the text. These values can be overridden by a different specification on the command line using the -p option.

Replace and Reverse Statements

REPLACE "search_pattern" WITH "replacement_string"
REVERSE "search_pattern" TO "replacement_string"

These statements are used to perform substitutions on the text surrounded by a box. The REPLACE statements are executed on the input text when a box is being created. REVERSE statements have the same effect as REPLACE statements, but they are executed after a box has been removed. In the simplest case, one string is replaced with another:

replace "\\*/" with "*-/"
reverse "\\*-/" to "*/"

The REPLACE statement in the above example may be used to quote closing comment tags in the C programming language by inserting a dash between the asterisk and the slash. The REVERSE statement undoes this effect when the box is removed.

The search pattern may be a regular expression, and the replacement string may include backreferences. This gives you quite a powerful means for text modification. The following example is used to insert a space between all characters of the input text:

replace "(.)" with "\\1 "
reverse "(.) " to "\\1"

There may be many REPLACE/REVERSE statements in one design definition. They will be executed one after the other, starting from the top.

Note that as in all strings, backslashes must be doubled, i.e. boxes “consumes one layer of backslashes”. This is why in the first example, there are two backslashes at the beginning of the search pattern, when only one would have been needed to escape the star operator. Alternately, you may use the delimiter statement to change the string delimiting and escape character.

For more information on how to use regular expressions, please see man 5 regexp, under “Basic Regular Expressions” or any other source.

Indentation Mode

INDENT "indentmode"

This sets the default indentation mode for a design. Possible values for indentmode are "box", "text", and "none". The indent mode specifies how existing text indentation is treated.

  • "box", which is the default setting, will cause the box to be indented by the same number of spaces as the text was. The text itself will not be indented within the box, though.
  • "text" will not indent the box, but instead retain the text indentation inside the box.
  • "none" will simply throw away all indentation.

For examples on all three indentation modes please refer to the example page.

String Delimiters


chars must consist of exactly two characters, the first of which being the escape character, and the second the string delimiter. No quotes must be placed around those two characters. The effect is that until the end of the current design or until the next DELIMITER statement, all strings must be enclosed not by the usual double quotes ("), but instead by the character you specify. Also, the delimiter may be escaped not by the usual backslash (\), but instead by the escape character you specify. For example, consider the literal string foo":"\"\\bar:


Using a DELIMITER statement, this looks much simpler:

delimiter ?:

The escape character may be any character you choose. The string delimiter, however, may only be one out of the following:


This set may change, but boxes will tell you your choices if you make a mistake.

Name of Author

AUTHOR "name_of_author"

Simply states who the ingenious guy/girl was who created the design. This entry is used when displaying the list of designs (boxes -l). The name should include the email address. Ideally, the entry should be usable “as is” in a TO: mail header, like this:

author "John Doe <>"

General Entries

keyword "string_value"

In addition to the author entry, there may be any number of other entries of the above form, giving any kind of information. The boxes config file includes the entries CREATED, REVISION, and REVDATE, to indicate the creation timestamp, revision number, and timestamp of the latest revision, respectively. These other entries are not yet used by boxes, though, and will simply be ignored.

Read on in the next part: A New Box Design Step By Step