Section: Your Own Document Language (1)Updated: 1996-2010Local indexUp
yodl - main Yodl converter
yodl [OPTION]... [FILE]...
Yodl is a package that implements a pre-document language and
tools to process it. The idea of Yodl is that you write up a document
in a pre-language, then use the tools (e.g. yodl2html(1)) to convert it
to some final document language. Current converters are for HTML,
man, LaTeX, text and an experimental xml converter. Main
document types are "article", "report", "book" "manpage" and "letter". The
Yodl document language is designed to be easy to use and extensible.
NOTE: Starting with Yodl version 3.00.0 Yodl's default file inclusion
behavior has changed. The current working directory no longer remains fixed at
the directory in which Yodl is called, but is volatile, changing to the
directory in which a yodl-file is located. This has the advantage that Yodl's
file inclusion behavior now matches the way C's #include directive
operates; it has the disadvantage that it may break some current
documents. Conversion, however is simple but can be avoided altogether if the
-L (--legacy-include) option is used (see below).
-D, --define=NAME[=VALUE]: Defines name as a symbol. This
option is acts like DEFINESYMBOL(NAME)(). If =VALUE is added, NAME
is initialized to VALUE (identically to DEFINESYMBOL(NAME)(VALUE)).
-d, --definemacro=NAME=EXPANSION: Defines NAME as macro
expanding to EXPANSION
-h, --help: usage information is written to the standard error
stream, describing all of Yodl's options.
-i, --index[=file]: `file' is the name of the index file. By
default <outputbase>.idx is used. No default when output is written to
stdout. The index file is processed by Yodl's post-processor, yodlpost.
-I, --include=DIR: This defines the system-wide include directory
where YODL searches for its input files. E.g. a statement to include a
given file, like:
will cause Yodl to search for the file latex in the current directory,
and when that fails, in the system-wide include directory. The system-wide
include directory is typically the place where the maintainer of a system
stores macro-files for Yodl. This searching process applies to files that are
included inside a document but also applies to filenames on the command line
when invoking the YODL program.
The name of the included file (latex in the above example) is the bare
name, the YODL program will supply a default extension (.yo), if necessary.
The -I option overrules Yodl's built-in name for the system-wide
include directory. The built-in name is defined when compiling Yodl, and is,
e.g., /usr/share/yodl. Furthermore, the definition may contain $HOME,
which will be replaced by the user's home directory if the `home' or `HOME'
environment variable is defined. It may also contain $STD_INCLUDE, which will
be replaced by the compilation defined standard include path. The standard
includepath may be overruled by either (in that order) the command line switch
-I or the YODL_INCLUDE_PATH environment variable. By default, the
current directory is added to the standard include path. Hewver, when -I
or YODL_INCLUDE_PATH is used, the current directory must be mentioned
explicitly. The individual directories need not be terminated by a
/-character. In distributed .deb archives, the standard directory is
defined as /usr/share/yodl (prefixed by the current working directory).
-k, --keep-ws: Since YODL version 2.00 blanks at the begin and end
of lines are ignored, even without a trailing \, when the `white space level'
is non-zero. Earlier versions kept these blanks. The legacy handling of white
space at end of lines can by obtained using the -k flag. Note that white
space are always kept when using verbatim copying, and when the white-space
level is zero.
-l, --live-data=HOW: This option controls the policy for
executing SYSTEM or PIPETHROUGH commands; HOW being none (0)
by default. The HOW argument can have the following values:
none or 0: (the default): No macros calling system programs are
confirm or 1: The macros can be executed, but only after user
confirmation is obtained. The macros in question are shown while the Yodl
document is processed, and the user must either accept or reject the call.
report or 2: The macros are executed, but what is called is shown
during the Yodl run (if the WARNING message level is active).
ok or 3: The macros are executed, and not shown during the
run. Be careful when using --live-data ok. It should be used only when a
document is clearly `unharmful'.
-m, --messages=SET: Set the so-called `message level'
to a combination of the SET acdeinw. The letters of this set have the
a: alert. When an alert-error occurs, Yodl terminates. Here Yodl
requests something of the system (like a get_cwd()), but the system fails.
c: critical. When a critical error occurs, Yodl terminates. The
message itself can be suppressed, but exiting can't. A critical condition is,
e.g., the omission of an open parenthesis at a location where a parameter list
should appear, or a non-existing file in an INCLUDEFILE specification (as
this file should be parsed). A non-existing file with a NOEXPANDINCLUDE
specification is a plain (non-critical) error.
d: debug. Probably too much info, like getting information about
each character that was read by Yodl.
e: error. An error (like doubly defined symbols). Error messages
will not stop the parsing of the input (up to a maximum number of errors),
but no output is generated.
i: info. Not as detailed as `debug', but still very much info,
like information about media switches.
n: notice. Information about, e.g., calls to the builtin
w: warning. Something you should know about, but probably not
affecting Yodl's proper functioning
Non-configurable is the handling of an emergency message. These
messages can't be suppressed, but shouldn't happen, as they point to some
internal error. It would be appreciated to
about these messages if they ever occur.
-n, --max-nested-files=NR: This option causes Yodl to abort when
the number of nested input files exceeds NR, which is 20 by
default. Exceeding this number usually means a circular definition somewhere
in the document. This is the case when, a file a.yo includes b.yo,
while b.yo includes a.yo etc.. It does not prevent recursive macro- or
subst-replacements. For that the -r (--max-replacements) option is
-o, --output=FILE: This option causes Yodl to write its output to
FILE. By default, the output goes to the standard output stream. E.g.,
you can use YODL to read a file input and to write to
output with the following two commands:
yodl input > output
yodl -ooutput input
The difference being that in the latter case an index file is generated,
but not in the former case. Notice that writing an index file can be forced
when the --index option is specified.
-p, --preload=CMD: This option `pre-loads' the string cmd. It
acts as though cmd was the first command in the first input file that is
processed by YODL.
More than one --preload=CMD options may be present on the command
line. Each of the commands is then processed in turn, before reading
-r, --max-replacements=NR: This option causes Yodl to abort when
the number of macro calls or subst-replacements exceeds NR * 10,000.
By default, NR equals 1. Setting --max-replacements=0 implies that
no macro- or subst-replacement checks are performed.
-t, --trace: This option enables tracing: while parsing, Yodl
writes its output to the standard error stream. As is the case with the -k
option, this option is defined for debugging purposes only.
-V, --version. This option will show YODL's actual version.
-v, --verbose: This option increases Yodl's `verbosity level' and
may occur more than once. By default yodl will show alerting, critical,
emergency and error messages. Each --verbose option will add a next
message level. In order, warning, notice, info and debug messages will be
added to this set. It is also possible to suppress messages. The
VERBOSITY builtin can be used for that.
-W, --warranty. This option will show a warranty disclaimer and a
-w, --warn: The presence of this option caused Yodl to warn when,
e.g., symbols are redefined.
The yodl program requires no files, but `normal' usage of the Yodl
package requires macro files, by default installed in
files in this directory are included by the converters yodl2txt(1)