Re: Bug in pr?

[Jim Meyering]

Richard Stallman <address@hidden> wrote:
> The pr program has what may arguably be a bug: when used with -F, it
> ends the last line on a page with a newline.  With the printer
> here (and maybe all printers nowadays), that causes a blank page
> after each real page.
>
> Maybe it would be better for pr to omit the newline before a
> formfeed.
>
> What do you think?

Thanks for the report.

The standard says this wrt -F:

    -F    Use a <form-feed> for new pages, instead of the
          default behavior that uses a sequence of <newline>s.

So that seems to leave enough wiggle room to make a change, if needed.
Does anyone know if a formfeed is reliably recognized even when it
does not follow a newline?

I see that GNU pr works the same way as the vendor pr
from Solaris 10's /usr/xpg4/bin/pr, OpenBSD 3.9, and NetBSD 1.6
in that respect:

    $ echo a|/usr/bin/pr -F|cat -A
    $
    $
    Jul  2 11:40 2007  Page 1$
    $
    $
    a$
    ^L$

Hmm...

I see that GNU pr -F gives slightly different output:
[note the missing pair of leading newlines; date format doesn't matter]

    $ echo a|pr -F|cat -A
    2007-07-02 18:41                                                  Page 1$
    $
    $
    a$
    ^L$

Perhaps you can simply filter the output of pr through a filter
to eliminate the offending newline(s)?  E.g., this is not terribly
efficient, but it's short and does the job:

    perl -0 -pe 's/\n+\f/\f/'

The advantage of adding a filter is that it should work with
any version of pr.

I see that GNU pr's documentation for -F is at odds with POSIX's
XSI requirement for pr -F:

          The pr utility output shall be a paginated version of the original
          file (or files). This pagination shall be accomplished using either
          <form-feed>s or a sequence of <newline>s, as controlled by
    XSI   the -F  or -f option. Page headers shall be generated unless the -t
          option is specified. The page headers shall be of the form:
          "\n\n%s %s Page %d\n\n\n", <output of date>, <file>, <page number>

Looks like one or the other should change.