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groff_trace(7)

NAME

       groff_trace - groff macro package trace.tmac

SYNOPSIS

       groff -m trace [options...] [files...]

       Elements  in brackets denote optional arguments, and the ellipsis means
       that there can be any number of arguments of this kind.

DESCRIPTION

       The trace macro package of groff(1) can be a valuable tool  for	debug-
       ging  documents	written in the roff formatting language.  A call stack
       trace is protocolled on standard error, that means, a  diagnostic  mes-
       sage  is emitted on entering and exiting of a macro call.  This greatly
       eases to track down an error in some macro.

       This tracing process is activated by specifying the groff or troff com-
       mand  line option -m trace.  This works also with the groffer(1) viewer
       program.  A finer control can be obtained by including the  macro  file
       within  the  document  by  the  groff macro call .mso trace.tmac.  Only
       macros that are defined after this line are traced.

       If some other macro package should be traced as well it must be	speci-
       fied after -m trace on the command line.

       The  macro  file  trace.tmac is unusual because it does not contain any
       macros to be called by a user.  Instead, the existing macro  definition
       and appending facilities are modified such that they display diagnostic
       messages.

EXAMPLES

       In the following examples, a roff fragment is fed into groff via  stan-
       dard  input.   As  we  are  only  interested in the diagnostic messages
       (standard error) on the terminal, the normal formatted output (standard
       output) is redirected into the nirvana device /dev/null.  The resulting
       diagnostic messages are	displayed  directly  below  the  corresponding
       example.

   Command line option
       sh# echo '.
       >   .de test_macro
       >   ..
       >   .test_macro
       >   .test_macro some dummy arguments
       >   ' | groff -m trace >/dev/null

       *** de trace enter: test_macro
       *** trace exit: test_macro
       *** de trace enter: test_macro "some" "dummy" "arguments"
       *** trace exit: test_macro "some" "dummy" "arguments"

       The  entry and the exit of each macro call is displayed on the terminal
       (standard output) -- together with the arguments (if any).

   Nested macro calls

       *** de trace enter: parent
       *** de trace enter: child
       *** trace exit: child
       *** trace exit: parent

       This shows that macro calls can be nested.  This powerful  feature  can
       help to tack down quite complex call stacks.

   Activating with .mso
       sh# echo '.
       >   .de before
       >   ..
       >   .mso trace.tmac
       >   .de after
       >   ..
       >   .before
       >   .after
       >   .before
       >   ' | groff >/dev/null

       *** de trace enter: after
       *** trace exit: after

       Here,  the  tracing  is activated within the document, not by a command
       line option.  As tracing was not active when macro before was  defined,
       no  call of this macro is protocolled; on the other hand, the macro af-
       ter is fully protocolled.

FILES

       The trace macros are kept in the file trace.tmac located  in  the  tmac
       directory; see groff_tmac(5) for details.

ENVIRONMENT

       $GROFF_TMAC_PATH
	      A  colon-separated  list of additional tmac directories in which
	      to search for macro files; see groff_tmac(5) for details.

AUTHOR

       Copyright (C) 2002 Free Software Foundation, Inc.

       This document is distributed under the terms of the FDL (GNU Free Docu-
       mentation  License)  version  1.1 or later.  You should have received a
       copy of the FDL on your system, it is also available on-line at the GNU
       copyleft site <http://www.gnu.org/copyleft/fdl.html>.

       This  document  is  part  of  groff, the GNU roff distribution.	It was
       written by Bernd Warken <bwarken@mayn.de>.

SEE ALSO

       groff(1)
	      An overview of the groff system.

       troff(1)
	      For details on option -m.

       groffer(1)
	      A viewer program for all kinds of roff documents.
       groff info(1) file.

Groff Version 1.19		11 October 2002 		GROFF_TRACE(7)

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