XMLIF(1)XMLIF(1)NAME
xmlif - conditional processing instructions for XML
SYNOPSIS
xmlif [attrib=value...]
DESCRIPTION
xmlif filters XML according to conditionalizing markup. This can be useful for formatting one of several versions of an XML document
depending on conditions passed to the command.
Attribute/value pairs from the command line are matched against the attributes associated with certain processing instructions in the docu-
ment. The instructions are <?if> and its inverse <?if not>, <?elif> and its inverse <?elif not>, <?else>, and <?fi>.
Argument/value pairs given on the command line are checked against the value of corresponding attributes in the conditional processing
instructions. An `attribute match' happens if an attribute occurs in both the command-line arguments and the tag, and the values match. An
`attribute mismatch' happens if an attribute occurs in both the command-line arguments and the tag, but the values do not match.
Spans between <?if> or <?elif> and the next conditional processing instruction at the same nesting level are passed through unaltered if
there is at least one attribute match and no attribute mismatch; spans between <?if not> and <?elif not> and the next conditional process-
ing instruction are passed otherwise. Spans between <?else> and the next conditional-processing tag are passed through only if no previous
span at the same level has been passed through. <?if> and <?fi> (and their `not' variants) change the current nesting level; <?else> and
<?elif> do not.
All these processing instructions will be removed from the output produced. Aside from the conditionalization, all other input is passed
through untouched; in particular, entity references are not resolved.
Value matching is by string equality, except that "|" in an attribute value is interpreted as an alternation character. Thus, saying
foo='red|blue' on the command line enables conditions red and blue. Saying color='black|white' in a tag matches command-line conditions
color='black' and color='white'.
Here is an example:
Always issue this text.
<?if condition='html'>
Issue this text if 'condition=html' is given on the command line.
<?elif condition='pdf|ps'>
Issue this text if 'condition=pdf' or 'condition=ps'
is given on the command line.
<?else>
Otherwise issue this text.
<?fi>
Always issue this text.
FUTURE DIRECTIONS
The mark-up used by this tool is not set in stone, and may change in the near future.
AUTHOR
Eric S. Raymond.
Sep 26 2002 XMLIF(1)
Check Out this Related Man Page
unifdef(1) General Commands Manual unifdef(1)NAME
unifdef - Removes #ifdefed lines
SYNOPSIS
unifdef [-tlc] [-Dsymbol] [-idsymbol] [-iusymbol] [file] [-Usymbol]
The unifdef command partially simulates the behavior of the C preprocessor in processing #ifdef conditionals.
OPTIONS
Complements the action of unifdef; retains lines that would normally be removed and removes lines that would normally be retained. Speci-
fies symbol as a defined #ifdef symbol. Specifies defined lines inside certain #ifdefs to be ignored but copied out. Specifies undefined
lines inside certain #ifdefs to be ignored and not copied out. Replaces removed lines with blank lines instead of deleting them. Pro-
cesses plain text (rather than C code) input. The unifdef command does not try to recognize comments, single quotes, and double quotes.
Specifies symbol as an undefined #ifdef symbol.
DESCRIPTION
The unifdef command recognizes nested #ifdefs, comments, single and double quotes of C syntax so that it can function correctly, but does
not include files or interpret macros. The unifdef command recognizes, but does not remove comments.
The unifdef command takes its input from stdin if no file argument is given, and copies its output to stdout.
You specify the symbols you want defined with -Dsymbol or undefined with -Usymbol and the lines inside those #ifdefs are copied to the out-
put or removed, as appropriate. The #ifdef, #ifndef, #else, #elif, and endif lines associated with symbol are also removed. The #ifdefs
involving unspecified symbols are untouched and copied out along with their associated #ifdef, #else, elif, and #endif lines. If the same
symbol appears in more than one argument, only the first occurrence is significant. For instance, if an #ifdef X occurs nested inside
another #ifdef X, the inside #ifdef is considered an unrecognized symbol.
If you use #ifdefs to delimit non-C lines, such as comments or unfinished code, it is necessary to specify which symbols are to be used for
that purpose. Otherwise, the unifdef command tries to parse for quotes and comments in those #ifdef lines.
Keywords
The following keywords can be used with the unifdef command:
ifdef ifndef else endif elif
The unifdef command uses the elif keyword as follows. (Note that "Understood" means unifdef knows how to convert elif to if.) Understood
Not understood Not understood
For example:
# ifdef X x # elif defined (Y) y # elif defined (A) || defined (B) a # else default # endif
The following list shows the results of using the elif keyword with variables:
-DX x
-UX # if defined (Y) y # elif defined (A) || defined (B) a # else default # endif -UX -DY y
-UY -UX # if defined (Y) y # elif defined (A) || defined (B) a # else default # endif
-UY -UX -DA # if defined (Y) y # elif defined (A) || defined (B) a # else default # endif
NOTES
The unifdef command cannot process cpp constructs such as:
#if defined(X) || defined(Y)
DIAGNOSTICS
The unifdef command can fail for several reasons: a premature end of file, or an inappropriate else, elif, or endif.
EXIT STATUS
Exit status is 0 if output is an exact copy of input, 1 if not, 2 if the unifdef command fails.
EXAMPLES
The following command line causes the unifdef command to read the file original.c and remove the #ifdef A lines. It then removes every-
thing following an #elif/#else associated with the #ifdef A down to the #endif: unifdef -DA original.c > modified.c The following command
line causes the unifdef command to read the file original.c, and remove the #ifdef A down to either its associated #elif/#else, or its
associated #endif: unifdef -UA original.c > modified.c
In the case of the #elif, the #elif is replaced with #if. In the case of #else, the #else is deleted along with its associated
#endif.
SEE ALSO
Commands: diff(1)unifdef(1)