On Wed, 2021-02-10 at 17:06 +0100, Erik Auerswald wrote: > Hi, > > On Wed, Feb 10, 2021 at 01:42:29PM +0100, Leonard Janis Robert König > wrote: > > I'm sorry if I this is not a bug but to be expected, but I thnk pr > > doesn't get the alignment of tabs in multicolumn output right. > > [...] > > Unfortunately the POSIX spec is, in my reading, a bit unclear here. > > I do not think so: > > -column > Produce multi-column output that is arranged in column > columns[...]. > The options -e and -i shall be assumed for multiple text-column > output. > > -e[char][gap] > Expand each input <tab> to the next greater column position[...]. > > -i[char][gap] > In output, replace multiple <space>s with <tab>s wherever[...]. > > https://pubs.opengroup.org/onlinepubs/009695399/utilities/pr.html > https://pubs.opengroup.org/onlinepubs/9699919799/utilities/pr.html > > The way I read the POSIX spec, "pr" needs to account for the column > separation by adjusting whitespace while still using tab characters > in > the output.
What's unclear however, whether this adjusting whitespace (replacing space by tab, as is the default) should happen on input or after arranging the text into columns. The former produces something resembling the GNU output as the tabs in the input files are kept, despite not aligning to 8 characters anymore. The latter produces the SunOS/FreeBSD output, as first the text is arranged and then tabs recalculated. > > But I think the behavior of GNU/pr is rather unexpected when > > printing > > multicolumn source code and not in line what the original authors > > intended. > > I concur. This makes tabs as input while using column or merge basically unusable though, as the characters are completely misaligned. This is especially bad for code. My use case is a script that prints the UNIX v6 source code in fashion of John Lion (see v6.cuzoco.com) and it breaks under GNU pr, but not on BSD, Solaris. And it seems to have worked also on Amdahl UTS in the late 80s for that matter. With regards to the original intent, I just tested this on Research UNIX v6 with SIMH (https://gunkies.org/wiki/Installing_Unix_v6_(PDP-11)_on_SIMH), and indeed the output is like the SunOS and FreeBSD version do: # pr -t -2 foo 123456781234567812345678123456781 123456781234567812345678123456781 x x x x x x x x x x N.B. that the input file must be little longer since the original version didn't produce identical vertical lengths as is allowed as per the standard: > Whether or not text columns are produced with identical vertical > lengths is unspecified [...] . At least to me this behavior of GNU pr came as a big surprise, maybe this should be described in the FAQ/Gotchas or the BUGS section of the manual? ~ leo
