Re: Unsupported nroff macros on MacOS X

[Steffen Nurpmeso]

Anthony J. Bentley wrote in
 <2866-1680590811.027894@HNc7.HHYy.EPMR>:
 |Ken Hornstein writes:
 |> Let's take the example you gave where the first line for a man
 |> page that uses tbl should contain:
 |>
 |> '\" t
 |>
 |> So, my question is ... what does this mean?  I understand that \" is
 |> a comment, but I'm confused about the leading single quote.
 ...
 |As for why the 't' is there, it's strictly a manpage practice, not
 |a general roff authoring practice. man(1) peeks at the comment (man-db
 |does anyway; pretty sure mandoc doesn't need it) to determine which
 |preprocessors to run. E.g., a manual that needs the eqn preprocessor
 |would have an 'e' instead.
 |
 |Normally the person piping a document through troff would be the author,
 |and would already know that the document contains tables that require
 |the source to be preprocessed with tbl. But manuals are formatted by
 |users; the man(1) program doesn't know the document features in advance,
 |and wants to avoid running preprocessors unless they're necessary.

   For example, newer man(1)s read the first line of the manual and
   check for a syntax <^'\" >followed by concat of [egprtv]+ (and in
   fact  *join in* $MANROFFSEQ environment [egprtv]+)
                while getopts 'egprtv' preproc_arg; do
                        case "${preproc_arg}" in
                        e)      pipeline="$pipeline | $EQN" ;;
                        g)      GRAP  ;; # Ignore for compatibility.
                        p)      pipeline="$pipeline | $PIC" ;;
                        r)      pipeline="$pipeline | $REFER" ;;
                        t)      pipeline="$pipeline | $TBL" ;;
                        v)      pipeline="$pipeline | $VGRIND" ;;
                        *)      usage ;;
                        esac

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)