Request and Macro Arguments - The GNU Troff Manual

5.5.1.1 Request and Macro Arguments

Arguments to requests and macros are processed much like the shell: The line is split into arguments according to spaces.¹

An argument to a macro which is intended to contain spaces can either be enclosed in double quotes, or have the spaces escaped with backslashes. This is not true for requests.

Here are a few examples for a hypothetical macro uh:

     
     .uh The Mouse Problem
     .uh "The Mouse Problem"
     .uh The\ Mouse\ Problem

The first line is the uh macro being called with 3 arguments, ‘The’, ‘Mouse’, and ‘Problem’. The latter two have the same effect of calling the uh macro with one argument, ‘The Mouse Problem’.²

A double quote which isn't preceded by a space doesn't start a macro argument. If not closing a string, it is printed literally.

For example,

     
     .xxx a" "b c" "de"fg"

has the arguments ‘a"’, ‘b c’, ‘de’, and ‘fg"’. Don't rely on this obscure behaviour!

There are two possibilities to get a double quote reliably.

Enclose the whole argument with double quotes and use two consecutive double quotes to represent a single one. This traditional solution has the disadvantage that double quotes don't survive argument expansion again if called in compatibility mode (using the -C option of groff):

          
          .de xx
          .  tm xx: `\\$1' `\\$2' `\\$3'
          .
          .  yy "\\$1" "\\$2" "\\$3"
          ..
          .de yy
          .  tm yy: `\\$1' `\\$2' `\\$3'
          ..
          .xx A "test with ""quotes""" .
              ⇒ xx: `A' `test with "quotes"' `.'
              ⇒ yy: `A' `test with ' `quotes""'

If not in compatibility mode, you get the expected result

          
          xx: `A' `test with "quotes"' `.'
          yy: `A' `test with "quotes"' `.'

since gtroff preserves the input level.

Use the double quote glyph \(dq. This works with and without compatibility mode enabled since gtroff doesn't convert \(dq back to a double quote input character.
Note that this method won't work with UNIX troff in general since the glyph `dq' isn't defined normally.

Double quotes in the ds request are handled differently. See Strings, for more details.

Footnotes

[1] Plan 9's troff implementation also allows tabs for argument separation – gtroff intentionally doesn't support this.

[2] The last solution, i.e., using escaped spaces, is “classical” in the sense that it can be found in most troff documents. Nevertheless, it is not optimal in all situations, since ‘\ ’ inserts a fixed-width, non-breaking space character which can't stretch. gtroff provides a different command \~ to insert a stretchable, non-breaking space.