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GROFF_TRACE(7)	       Miscellaneous Information Manual		GROFF_TRACE(7)

       groff_trace - groff macro package trace.tmac

       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.

       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

       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  ex-

   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
       sh# echo	'.
       _   .de child
       _   ..
       _   .de parent
       _   .child
       _   ..
       _   .parent
       _   ' | groff -m	trace >/dev/null

       *** 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.

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

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

       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 <>.

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

	      An overview of the groff system.

	      For details on option -m.

	      A	viewer program for all kinds of	roff documents.

	      A	general	description of groff macro packages.

	      A	short reference	for the	groff formatting language.

       A complete reference for	all parts of the groff system is found in  the
       groff info(1) file.

Groff Version 1.18.1		08 August 2020			GROFF_TRACE(7)


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