Re: [eqn] error: invalid input (character code 159)

[Ralph Corderoy]

Hi Alejandro,

> To me man(1) is still a black box (I have looked at its source code
> occasionally, but not very often), and there's no way to know what
> it's doing, since it provides no equivalent to groff(1)'s -V.

Colin Watson's man(1) uses his libpipeline(3).

    $ PIPELINE_DEBUG=1 man ls 2>&1 >/dev/null | grep '^Starting pipeline:'
    Starting pipeline:
        zcat
        [input: {0, /usr/share/man/man1/ls.1p.gz}, output: {-1, NULL}]
    Starting pipeline:
        zcat
        [input: {0, /usr/share/man/man1/ls.1.gz}, output: {-1, NULL}]
    Starting pipeline:
        zcat
        [input: {0, /usr/share/man/man1/ls.1.gz}, output: {-1, NULL}]
    Starting pipeline:
        (echo .nh && echo .de hy && echo .. && echo .na && echo .de ad && echo 
.. && zcat)
        [input: {0, /usr/share/man/man1/ls.1.gz}, output: {-1, NULL}]
    Starting pipeline:
        (cd /usr/share/man && /usr/lib/man-db/zsoelim) |
        (cd /usr/share/man && /usr/lib/man-db/manconv -f UTF-8:ISO-8859-1 -t 
UTF-8//IGNORE) |
        (cd /usr/share/man && preconv -e UTF-8) |
        (cd /usr/share/man && tbl) |
        (cd /usr/share/man && nroff -mandoc -rLL=265n -rLT=265n -Tutf8)
        [input: {-1, NULL}, output: {-1, NULL}]
    Starting pipeline:
        col -b -p -x |
        sed -e '/^[[:space:]]*$/{ N; /^[[:space:]]*\n[[:space:]]*$/D; }'
        [input: {-1, NULL}, output: {0, NULL}]
    Starting pipeline:
        zcat
        [input: {3, NULL}, output: {-1, NULL}]
    Starting pipeline:
        Waiting for pipeline: zcat
        [input: {3, NULL}, output: {-1, NULL}]
    $

> >     $ groff -Tascii -kpt -V
> >     preconv | pic | tbl | troff -Tascii | grotty
> >     $
>
> Does man(1) run pic(1)?

It can do.  It sometimes reads the man page to find out the
preprocessors to use.  Read around ‘MANROFFSEQ’ in man(1).

> BTW, you may notice I added some trick to make eqn(1) fail:
>
> <https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=e728d5d1e639e5c803a84480ad727e7b02bac222>

I'd grep for ^ as otherwise the code doesn't match the commit message.
:-)

-- 
Cheers, Ralph.