#

| Chapter 43 Printing |

## 43.20 Displaying a troff Macro Definition

If you're writing or debugging troff macros (43.13), you often need to review the contents of a macro. Rather than searching through the macro definition files with an editor, it is relatively easy to construct a small script that uses sed (34.24) and the shell to extract and display a single macro.

The script is easy to construct because the macro definitions have a regular structure that lends itself to easy identification with the regular expressions (26.4) used by sed. A troff macro definition always begins with the string `.de`, followed by an optional space and the one- or two-letter name of the macro. The definition ends with a line beginning with two dots (`..`).

troff macros are defined in a macro package, often a single file that's located in a directory such as /usr/lib/tmac. The most common macro packages are mm, ms and me-though it is unlikely that a given system will have all three. mm is generally found on System V-derived systems, and ms and me on BSD-derived systems. The man macros are found on just about all systems because they are used by the man command (50.1).

Here's an example:

>     % getmac -ms LP
>     .\"
>     .\" The following definition of LP was found in /usr/lib/tmac/tmac.s:
>     .\"
>     .de LP
>     .RT
>     .if \\n(1T .sp \\n(PDu

>     .ti \\n(.iu
>     ..

The getmac script is below. For those unfamiliar with sed, there are comments in the script on the CD-ROM (and in the online archive file):

>     #!/bin/sh
>     # Usage: getmac -package macro
>     case $1 in
>     -mm) file="/usr/lib/macros/mmt";;
>     -ms) file="/usr/lib/tmac/tmac.s";;
>     -me) file="/usr/lib/tmac/tmac.e";;
>     -man) file="/usr/lib/tmac/tmac.an";;
>     *) echo "Usage: getmac -package macro" 1>&2; exit 1;;
>     esac
>     mac=$2

>     sed -n '
>     /^\.de *'$mac'/,/^\.\.$/ {
>        /^\.de/i\
>     .\\"\
>     .\\" The following definition of '$mac' was found in '$file':\
>     .\\"
>        p
>        /^\.\.$/q
>     }' $file

- TOR, JP

43.19 Removing Leading Tabs and Other Trivia |  | 43.21 Preprocessing troff Input with sed