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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 ...]
The trace macro package of groff(1) can be a valuable tool for
debugging documents written in the roff formatting language. A call
stack trace is protocolled on standard error, this is, a diagnostic
message 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
command 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 command line option -r trace-full=1 is given (or if this register
is set in the document), number and string register assignments
together with some other requests are traced also.
If some other macro package should be traced as well it must be
specified 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.
In the following examples, a roff fragment is fed into groff via
standard input. As we are only interested in the diagnostic messages
(standard error) on the terminal, the normal formatted output
(standard output) is redirected to the nirvana device /dev/null. The
resulting diagnostic messages are displayed directly below the
corresponding example.
Command line option
Example:
sh# echo '.
> .de test_macro
> ..
> .test_macro
> .test_macro some dummy arguments
> ' | groff -m trace > /dev/null
*** .de test_macro
*** 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 termi‐
nal (standard output) — together with the arguments (if any).
Nested macro calls
Example:
sh# echo '.
> .de child
> ..
> .de parent
> .child
> ..
> .parent
> ' | groff -m trace > /dev/null
*** .de child
*** .de parent
*** 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
Example:
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 after is fully protocolled.
Because trace.tmac wraps the .de request (and its cousins), macro
arguments are expanded one level more. This causes problems if an
argument contains four backslashes or more to prevent too early
expansion of the backslash. For example, this macro call
.foo \\\\n[bar]
normally passes ‘\\n[bar]’ to macro ‘.foo’, but with the redefined
.de request it passes ‘\n[bar]’ instead.
The solution to this problem is to use groff's \E escape which is an
escape character not interpreted in copy mode, for example
.foo \En[bar]
The trace macros are kept in the file trace.tmac located in the tmac
directory; see groff_tmac(5) for details.
$GROFF_TMAC_PATH
A colon-separated list of additional tmac directories in which
to search for macro files; see groff_tmac(5) for details.
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_tmac(5)
A general description of groff macro packages.
groff(7)
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.
Copyright © 2002-2014 Free Software Foundation, Inc.
This file is part of groff, the GNU roff type-setting system.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being this .ig-section and AUTHOR, with no Front-
Cover Texts, and with no Back-Cover Texts.
A copy of the Free Documentation License is included as a file called
FDL in the main directory of the groff source package.
Written by Bernd Warken ⟨groff-bernd.warken-72@web.de⟩.
This page is part of the groff (GNU troff) project. Information
about the project can be found at
⟨http://www.gnu.org/software/groff/⟩. If you have a bug report for
this manual page, see ⟨http://www.gnu.org/software/groff/⟩. This
page was obtained from the tarball groff-1.22.3.tar.gz fetched from
⟨ftp://ftp.gnu.org/gnu/groff/⟩ on 2017-07-05. If you discover any
rendering problems in this HTML version of the page, or you believe
there is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
Groff Version 1.22.3 4 November 2014 GROFF_TRACE(7)
Pages that refer to this page: groff(1), groff_tmac(5)