groff_trace(7) Miscellaneous Information Manual groff_trace(7)
groff_trace - GNU roff macros for debugging groff documents
groff -m trace [option ...] [input-file ...]
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. 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 the 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 terminal (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.
The trace macro packages was written by James Clark. This document was written by Bernd Warken ⟨groff-bernd.warken-72@web .de⟩.
Groff: The GNU Implementation of troff, by Trent A. Fisher and Werner Lemberg, is the primary groff manual. You can browse it interactively with “info groff”. groff(1) An overview of the groff system. troff(1) For details on option -m. groff_tmac(5) A general description of groff macro packages. groff(7) A short reference for the groff formatting language.
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 project's upstream Git repository ⟨https://git.savannah.gnu.org/git/groff.git⟩ on 2021-06-20. (At that time, the date of the most recent commit that was found in the repository was 2021-06-17.) 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 email@example.com groff 1.23.0.rc1.654-4e1db-dirt1y6 June 2021 groff_trace(7)
Pages that refer to this page: groff_tmac(5)