bug#54516: closed (Sed help message error)

[GNU bug Tracking System]

Your message dated Mon, 21 Mar 2022 21:53:32 -0600
with message-id <20220321214440294606677@bob.proulx.com>
and subject line Re: bug#54516: Sed help message error
has caused the debbugs.gnu.org bug report #54516,
regarding Sed help message error
to be marked as done.

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54516: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=54516
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--- Begin Message --- Subject: Sed help message error Date: Mon, 21 Mar 2022 22:47:17 -0400

Hello there,

Here's a random bug I just found:

sed|sed 's/sed/bob/g;'

This should replace the word sed in the help but it doesn't since the help output is actually in the error pipe. With this version of the command it'll work however, which proves this:

sed 2>&1|sed 's/sed/bob/g;'

So, is this a feature or a bug considering "sed --help" outputs in the normal output pipe?

Thanks

--- End Message ---

> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#54516: Sed help message error
>
>
>
>
> Date: 
>
> Mon, 21 Mar 2022 21:53:32 -0600
>
>
>
>
> Rolf Johns wrote:
> > Here's a random bug I just found:
> > sed|sed 's/sed/bob/g;'
> > This should replace the word sed in the help but it doesn't since the help
> > output is actually in the error pipe. With this version of the command
> > it'll work however, which proves this:
> > sed 2>&1|sed 's/sed/bob/g;'
> >
> > So, is this a feature or a bug considering "sed --help" outputs in the
> > normal output pipe?
>
> Running sed without any options is a usage error.  Since sed requires
> at least a script as an argument parameter.  Since the sed script is
> missing sed is emitting an error message to standard error and exiting
> with an error status code.  (I'll note that awk does the same thing.)
>
>     $ sed 2>/dev/null ; echo $?
>     1
>
> The sed --help is not an error.  In that case sed is being asked for
> the help information.  And therefore it is being emitted to standard
> output instead of standard error.  The exit code is success.
>
>     $ sed --help >/dev/null ; echo $?
>     0
>
> All seems to be operating as desired.  Hope this explanation helps.
>
> It's arguable that upon an error that *less* information should be
> emitted to stderr.  Perhaps just the Usage line, a pointer to the
> --help output, and nothing more.  Then the usage error would be less
> likely to be confused with a help output message.  Such as for example
> the way tar behaves.
>
>     $ tar
>     tar: You must specify one of the '-Acdtrux', '--delete' or '--test-label' 
> options
>     Try 'tar --help' or 'tar --usage' for more information.
>     $ echo $?
>     2
>
> Bob
>
>
> --- End Message ---