[TUHS] basic tools / Universal Unix

Steffen Nurpmeso steffen at sdaoden.eu
Fri Oct 20 07:03:40 AEST 2017

Good evening everybody.

Random832 <random832 at fastmail.com> wrote:
 |On Thu, Oct 19, 2017, at 10:33, Steffen Nurpmeso wrote:
 |> Random832 <random832 at fastmail.com> wrote:
 |>|On Wed, Oct 18, 2017, at 19:03, Doug McIlroy wrote:
 |>|>> But mind you, in preparation of this email i found a bug in
 |>|>> Busybox sed(1) which simply echoes nothing for the above.
 |>|> I assume that * is a typo for - . If so, sed did just what
 |>|> -n tells it to--no printing except as called for by p or P.
 |>|Or, you know, l (the letter ell). Which busybox sed appears to not
 |>|support at all, rather than somehow misapplying -n to it.
 |> The letter l, yes.  But it does not fail either, so it knows about
 |> it, talking version 1.27.something here.
 |If you look at the source, it is in the list that is checked for
 |printing (or not) the 'unsupported command' error message, but there is
 |no actual code to handle it (and when called *without* -n, it just falls
 |through and prints once, just like if you'd had no command at all)

That is true.

 |I think that makes this a legitimate bug in busybox, rather than simply
 |an artifact of being a minimal tool that doesn't aim for posix (or
 |historical unix) conformance.

Yes, it should error out or implement the stuff i think.  The way
it is is not handable.
The comments in coreutils/cat.c are postable in this thread too:

/* Rob had "cat -v" implemented as a separate applet, catv.
[That is Rob AT Landley DOT NET]
 * See "cat -v considered harmful" at
 * http://cm.bell-labs.com/cm/cs/doc/84/kp.ps.gz
[This server has been killed]
 * From USENIX Summer Conference Proceedings, 1983
 * """
 * The talk reviews reasons for UNIX's popularity and shows, using UCB cat
 * as a primary example, how UNIX has grown fat. cat isn't for printing
 * files with line numbers, it isn't for compressing multiple blank lines,
 * it's not for looking at non-printing ASCII characters, it's for
 * concatenating files.
 * We are reminded that ls isn't the place for code to break a single column
 * into multiple ones, and that mailnews shouldn't have its own more
 * processing or joke encryption code.
 * """
 * I agree with the argument. Unfortunately, this ship has sailed (1983...).
 * There are dozens of Linux distros and each of them has "cat" which supports -v.
 * It's unrealistic for us to "reeducate" them to use our, incompatible way
 * to achieve "cat -v" effect. The actual effect would be "users pissed off
 * by gratuitous incompatibility".

And, indeed sailing (-vet explicitly compiled in):

  ?0[steffen at essex busybox.git]$ echo −e | cat -vet

Then again, you know, i personally have problems with -vet and
think the POSIX sed variant is easier to grasp:

  ?0[steffen at essex busybox.git]$ echo −e | sed -n l

|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)

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