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Info Node: (m4.info)Debug Levels

(m4.info)Debug Levels


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Controlling debugging output
============================

   The `-d' option to `m4' controls the amount of details presented,
when using the macros described in the preceding sections.

   The FLAGS following the option can be one or more of the following:

`t'
     Trace all macro calls made in this invocation of `m4'.

`a'
     Show the actual arguments in each macro call.  This applies to all
     macro calls if the `t' flag is used, otherwise only the macros
     covered by calls of `traceon'.

`e'
     Show the expansion of each macro call, if it is not void.  This
     applies to all macro calls if the `t' flag is used, otherwise only
     the macros covered by calls of `traceon'.

`q'
     Quote actual arguments and macro expansions in the display with the
     current quotes.

`c'
     Show several trace lines for each macro call.  A line is shown
     when the macro is seen, but before the arguments are collected; a
     second line when the arguments have been collected and a third
     line after the call has completed.

`x'
     Add a unique `macro call id' to each line of the trace output.
     This is useful in connection with the `c' flag above.

`f'
     Show the name of the current input file in each trace output line.

`l'
     Show the the current input line number in each trace output line.

`p'
     Print a message when a named file is found through the path search
     mecanism (Note: Search Path), giving the actual filename used.

`i'
     Print a message each time the current input file is changed,
     giving file name and input line number.

`V'
     A shorthand for all of the above flags.

   If no flags are specified with the `-d' option, the default is
`aeq'. The examples in the previous two sections assumed the default
flags.

   There is a builtin macro `debugmode', which allows on-the-fly
control of the debugging output format:

     debugmode(opt FLAGS)

The argument FLAGS should be a subset of the letters listed above.  As
special cases, if the argument starts with a `+', the flags are added
to the current debug flags, and if it starts with a `-', they are
removed.  If no argument is present, the debugging flags are set to
zero (as if no `-d' was given), and with an empty argument the flags
are reset to the default.


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