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Re: shred bug? [was: Unidentified subject!]

From Greg Wooledge <greg@wooledge.org>
Newsgroups linux.debian.user
Subject Re: shred bug? [was: Unidentified subject!]
Date 2024-02-13 13:20 +0100
Message-ID <I6ZVv-9SfF-1@gated-at.bofh.it> (permalink)
References (5 earlier) <I6j9T-9rHP-9@gated-at.bofh.it> <I6jjA-9rLR-3@gated-at.bofh.it> <I6jtf-9rP5-5@gated-at.bofh.it> <I6jWi-9shk-5@gated-at.bofh.it> <I6ZVv-9SfF-3@gated-at.bofh.it>
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On Mon, Feb 12, 2024 at 11:01:47PM -0600, David Wright wrote:
> … but not much. For me, "standard output" is /dev/fd/1, yet it seems
> unlikely that anyone is going to use >&1 in the manner of the example.

Standard output means "whatever file descriptor 1 points to".  That
could be a file, a pipe, a terminal (character device), etc.

> I might write something like: "The option ‘-’ shreds the file specified
> by the redirection ‘>&N’", though there could be a better name for ‘>&N’.

You're assuming the program will be used from a shell.  This is *usually*
going to be true, but nothing prevents you from writing a C program
which closes stdout, opens a file, ensures that it's using FD 1,
and then calls "shred -".  The documentation has to support this use
case as well.

> >    A FILE of ‘-’ denotes standard output.  The intended use of this is
> >    to shred a removed temporary file.  For example:
> > 
> >       i=$(mktemp)
> >       exec 3<>"$i"
> >       rm -- "$i"
> >       echo "Hello, world" >&3
> >       shred - >&3
> >       exec 3>-
> 
> I can see that the last line truncates the "anonymous" file,

No, that's not what it does at all.  In fact, that last line is
written incorrectly.  It should say "exec 3>&-" and what that does
is close file descriptor 3, which was previously opened on line 2.

What it actually does *as written* is create/truncate a file whose
name is "-", close the previously opened FD 3, and make FD 3 point
to the file named "-".

unicorn:~$ exec 3>-
unicorn:~$ ls -ld -- -
-rw-r--r-- 1 greg greg 0 Feb 13 07:12 -
unicorn:~$ ls -l /dev/fd/3
l-wx------ 1 greg greg 64 Feb 13 07:12 /dev/fd/3 -> /home/greg/-

This is an obvious bug in the info page.  I wonder how many years
this has gone unnoticed.

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Unidentified subject! gene heskett <gheskett@shentel.net> - 2024-02-07 21:40 +0100
  Re: Unidentified subject! Stefan Monnier <monnier@iro.umontreal.ca> - 2024-02-08 05:30 +0100
    Re: Unidentified subject! gene heskett <gheskett@shentel.net> - 2024-02-10 11:00 +0100
      Re: Unidentified subject! "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-10 11:40 +0100
        shred bug? [was: Unidentified subject!] <tomas@tuxteam.de> - 2024-02-10 13:50 +0100
          Re: shred bug? [was: Unidentified subject!] tomas@tuxteam.de - 2024-02-10 14:00 +0100
            Re: shred bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-10 15:00 +0100
              Re: shred bug? <tomas@tuxteam.de> - 2024-02-10 15:40 +0100
          Re: shred bug? Gremlin <scott-andrews@columbus.rr.com> - 2024-02-10 14:40 +0100
          Re: shred bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-10 14:40 +0100
          Re: shred bug? [was: Unidentified subject!] David Christensen <dpchrist@holgerdanske.com> - 2024-02-11 01:10 +0100
            Re: shred bug? [was: Unidentified subject!] Greg Wooledge <greg@wooledge.org> - 2024-02-11 01:20 +0100
              Re: shred bug? [was: Unidentified subject!] David Christensen <dpchrist@holgerdanske.com> - 2024-02-11 01:30 +0100
                Re: shred bug? [was: Unidentified subject!] debian-user@howorth.org.uk - 2024-02-11 14:00 +0100
                Re: shred bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-11 14:30 +0100
              Re: shred bug? [was: Unidentified subject!] <tomas@tuxteam.de> - 2024-02-11 08:10 +0100
                Re: shred bug? [was: Unidentified subject!] Greg Wooledge <greg@wooledge.org> - 2024-02-11 15:40 +0100
                Re: shred bug? [was: Unidentified subject!] <tomas@tuxteam.de> - 2024-02-11 15:50 +0100
                Re: shred bug? [was: Unidentified subject!] Greg Wooledge <greg@wooledge.org> - 2024-02-11 16:00 +0100
                Re: shred bug? [was: Unidentified subject!] <tomas@tuxteam.de> - 2024-02-11 16:00 +0100
                Re: shred bug? [was: Unidentified subject!] Greg Wooledge <greg@wooledge.org> - 2024-02-12 18:00 +0100
                Re: shred bug? [was: Unidentified subject!] Curt <curty@free.fr> - 2024-02-12 18:00 +0100
                Re: shred bug? [was: Unidentified subject!] David Christensen <dpchrist@holgerdanske.com> - 2024-02-12 22:00 +0100
                Re: shred bug? [was: Unidentified subject!] "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-12 22:10 +0100
                Re: shred bug? [was: Unidentified subject!] <tomas@tuxteam.de> - 2024-02-13 06:50 +0100
                Re: shred bug? [was: Unidentified subject!] David Wright <deblis@lionunicorn.co.uk> - 2024-02-11 16:30 +0100
                Re: shred bug? [was: Unidentified subject!] Greg Wooledge <greg@wooledge.org> - 2024-02-13 13:20 +0100
                Re: shred bug? [was: Unidentified subject!] Greg Wooledge <greg@wooledge.org> - 2024-02-13 13:40 +0100
                Re: shred bug? [was: Unidentified subject!] <tomas@tuxteam.de> - 2024-02-13 13:50 +0100
                Re: shred bug? [was: Unidentified subject!] "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-13 14:00 +0100
                Re: shred bug? [was: Unidentified subject!] David Wright <deblis@lionunicorn.co.uk> - 2024-02-13 16:40 +0100
                Re: shred bug? [was: Unidentified subject!] Greg Wooledge <greg@wooledge.org> - 2024-02-13 17:30 +0100
                Re: shred bug? [was: Unidentified subject!] debian-user@howorth.org.uk - 2024-02-13 18:50 +0100
                Re: shred bug? [was: Unidentified subject!] David Christensen <dpchrist@holgerdanske.com> - 2024-02-13 22:10 +0100
                Re: shred bug? [was: Unidentified subject!] <tomas@tuxteam.de> - 2024-02-14 06:50 +0100
                Re: shred bug? [was: Unidentified subject!] "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-13 19:00 +0100
                Re: shred bug? [was: Unidentified subject!] Greg Wooledge <greg@wooledge.org> - 2024-02-13 20:00 +0100
                Re: shred bug? [was: Unidentified subject!] "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-13 20:40 +0100
                Re: shred bug? [was: Unidentified subject!] gene heskett <gheskett@shentel.net> - 2024-02-13 20:40 +0100
                Re: shred bug? [was: Unidentified subject!] "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-13 20:50 +0100
                Re: shred bug? [was: Unidentified subject!] gene heskett <gheskett@shentel.net> - 2024-02-13 21:30 +0100
                Re: shred bug? [was: Unidentified subject!] David Christensen <dpchrist@holgerdanske.com> - 2024-02-13 22:10 +0100
                Re: shred bug? [was: Unidentified subject!] gene heskett <gheskett@shentel.net> - 2024-02-13 22:50 +0100
                Re: shred bug? [was: Unidentified subject!] David Wright <deblis@lionunicorn.co.uk> - 2024-02-15 06:40 +0100
                Re: shred bug? [was: Unidentified subject!] David Christensen <dpchrist@holgerdanske.com> - 2024-02-11 23:50 +0100
                Re: shred bug? [was: Unidentified subject!] Max Nikulin <manikulin@gmail.com> - 2024-02-13 03:40 +0100
                Re: shred bug? [was: Unidentified subject!] "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-11 16:30 +0100
                Re: shred bug? [was: Unidentified subject!] Michael Stone <mstone@debian.org> - 2024-02-16 16:00 +0100
        Re: Unidentified subject! gene heskett <gheskett@shentel.net> - 2024-02-10 18:50 +0100
          Re: Unidentified subject! "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-10 19:40 +0100
            Re: Unidentified subject! gene heskett <gheskett@shentel.net> - 2024-02-10 20:30 +0100
            Re: Unidentified subject! David Christensen <dpchrist@holgerdanske.com> - 2024-02-11 00:50 +0100
              Re: Unidentified subject! "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-11 09:10 +0100
                Re: Unidentified subject! David Christensen <dpchrist@holgerdanske.com> - 2024-02-11 21:50 +0100
        Re: Unidentified subject! David Christensen <dpchrist@holgerdanske.com> - 2024-02-11 00:40 +0100
          Re: Unidentified subject! "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-11 09:20 +0100
            Re: Unidentified subject! David Christensen <dpchrist@holgerdanske.com> - 2024-02-11 11:10 +0100
              Fast Random Data Generation (Was: Re: Unidentified subject!) Linux-Fan <Ma_Sys.ma@web.de> - 2024-02-11 11:30 +0100
                Re: Fast Random Data Generation "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-11 12:30 +0100
                Re: Fast Random Data Generation (Was: Re: Unidentified subject!) Gremlin <scott-andrews@columbus.rr.com> - 2024-02-11 13:20 +0100
                Re: Fast Random Data Generation (Was: Re: Unidentified subject!) David Christensen <dpchrist@holgerdanske.com> - 2024-02-12 07:20 +0100
                Re: Fast Random Data Generation (Was: Re: Unidentified subject!) Linux-Fan <Ma_Sys.ma@web.de> - 2024-02-12 17:40 +0100
                Re: Fast Random Data Generation (Was: Re: Unidentified subject!) David Christensen <dpchrist@holgerdanske.com> - 2024-02-12 22:30 +0100
                Re: Fast Random Data Generation (Was: Re: Unidentified subject!) Linux-Fan <Ma_Sys.ma@web.de> - 2024-02-13 18:40 +0100
                Re: Fast Random Data Generation (Was: Re: Unidentified subject!) Jeffrey Walton <noloader@gmail.com> - 2024-02-12 22:30 +0100
              Re: Unidentified subject! "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-11 12:20 +0100
                Re: Unidentified subject! Jeffrey Walton <noloader@gmail.com> - 2024-02-11 16:20 +0100
                Re: Unidentified subject! David Christensen <dpchrist@holgerdanske.com> - 2024-02-11 23:00 +0100
      Re: Unidentified subject! Stefan Monnier <monnier@iro.umontreal.ca> - 2024-02-10 15:40 +0100
  Things I don't touch with a 3.048m barge pole: USB storage (Was Re:  Unidentified subject!) Andy Smith <andy@strugglers.net> - 2024-02-08 16:40 +0100
    Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Gremlin <scott-andrews@columbus.rr.com> - 2024-02-08 17:20 +0100
      Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Andy Smith <andy@strugglers.net> - 2024-02-08 17:30 +0100
      Re: Things I don't touch with a 3.048m barge pole: USB storage  (WasRe: Unidentified subject!) gene heskett <gheskett@shentel.net> - 2024-02-09 09:50 +0100
    Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Ralph Aichinger <ra@h5.or.at> - 2024-02-08 18:00 +0100
      Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Jeffrey Walton <noloader@gmail.com> - 2024-02-08 20:30 +0100
        Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Andy Smith <andy@strugglers.net> - 2024-02-08 21:50 +0100
        Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Andy Smith <andy@strugglers.net> - 2024-02-08 21:50 +0100
          Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Gremlin <scott-andrews@columbus.rr.com> - 2024-02-08 22:00 +0100
            Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Andy Smith <andy@strugglers.net> - 2024-02-08 22:20 +0100
              Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Andy Smith <andy@strugglers.net> - 2024-02-08 22:30 +0100
                Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Gremlin <scott-andrews@columbus.rr.com> - 2024-02-08 23:10 +0100
              Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Gremlin <scott-andrews@columbus.rr.com> - 2024-02-08 22:30 +0100
          Re: Things I don't touch with a 3.048m barge pole: USB storage  (WasRe: Unidentified subject!) gene heskett <gheskett@shentel.net> - 2024-02-09 14:00 +0100
            Re: Things I don't touch with a 3.048m barge pole "Thomas Schmitt" <scdbackup@gmx.net> - 2024-02-09 14:50 +0100
            Re: Things I don't touch with a 3.048m barge pole: USB storage  (WasRe: Unidentified subject!) David Christensen <dpchrist@holgerdanske.com> - 2024-02-10 07:00 +0100
              Re: Things I don't touch with a 3.048m barge pole: USB storage(WasRe:  Unidentified subject!) gene heskett <gheskett@shentel.net> - 2024-02-10 18:40 +0100
      Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Andy Smith <andy@strugglers.net> - 2024-02-08 21:40 +0100
        Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Arno Lehmann <al@its-lehmann.de> - 2024-02-09 09:50 +0100
    Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Max Nikulin <manikulin@gmail.com> - 2024-02-08 18:30 +0100
      Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Andy Smith <andy@strugglers.net> - 2024-02-08 21:40 +0100
        Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Gremlin <scott-andrews@columbus.rr.com> - 2024-02-08 22:10 +0100
          Re: Things I don't touch with a 3.048m barge pole: USB storage (Was  Re: Unidentified subject!) Andy Smith <andy@strugglers.net> - 2024-02-08 22:20 +0100
  Re: Unidentified subject! Richmond <dnomhcir@gmx.com> - 2024-02-08 23:50 +0100
    Re: Unidentified subject! Stefan Monnier <monnier@iro.umontreal.ca> - 2024-02-09 00:10 +0100
      Re: Unidentified subject! Charles Curley <charlescurley@charlescurley.com> - 2024-02-09 00:50 +0100
        Re: Unidentified subject! Richmond <dnomhcir@gmx.com> - 2024-02-09 05:50 +0100
          Re: Unidentified flying subject! Charles Curley <charlescurley@charlescurley.com> - 2024-02-09 07:50 +0100
            Re: Unidentified flying subject! Richmond <dnomhcir@gmx.com> - 2024-02-09 14:20 +0100

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