GNU bug report logs - #19604
echo --help does not work

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: prateek goyal <prateek.goyal5 <at> gmail.com>
To: bug-coreutils <at> gnu.org
Subject: echo --help does not work
Date: Thu, 15 Jan 2015 11:50:34 +0530

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Hi,


when I try to use --help option with echo command, it does not print help
contents, but prints "--help".


prateek <at> prateek-pc:~/Documents/awk$ echo --help
--help


Version and OS:

Linux prateek-pc 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC
2014 x86_64 x86_64 x86_64 GNU/Linux


-- 

*Thanks,Prateek Goyal*

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Message #8 received at 19604 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: prateek goyal <prateek.goyal5 <at> gmail.com>, 19604 <at> debbugs.gnu.org
Subject: Re: bug#19604: echo --help does not work
Date: Thu, 15 Jan 2015 11:36:32 +0000

tag 19604 notabug
close 19604
stop

On 15/01/15 06:20, prateek goyal wrote:
> Hi,
> 
> 
> when I try to use --help option with echo command, it does not print help contents, but prints "--help".
> 
> 
> prateek <at> prateek-pc:~/Documents/awk$ echo --help
> --help

You're actually using your shell's echo there.
To use the coreutils one:

  env echo --help

To invoke help for the shell builtin in bash you:

  help echo

Note newer versions of bash will support $builtin --help,
though I've not tested the echo case which would
introduce a change in behavior.

thanks,
Pádraig.

Message #15 received at 19604 <at> debbugs.gnu.org (full text, mbox):

From: Eric Blake <eblake <at> redhat.com>
To: Pádraig Brady <P <at> draigBrady.com>,
 prateek goyal <prateek.goyal5 <at> gmail.com>, 19604 <at> debbugs.gnu.org
Subject: Re: bug#19604: echo --help does not work
Date: Thu, 15 Jan 2015 07:09:18 -0700

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On 01/15/2015 04:36 AM, Pádraig Brady wrote:
> tag 19604 notabug
> close 19604
> stop
> 
> On 15/01/15 06:20, prateek goyal wrote:
>> Hi,
>>
>>
>> when I try to use --help option with echo command, it does not print help contents, but prints "--help".
>>
>>
>> prateek <at> prateek-pc:~/Documents/awk$ echo --help
>> --help
> 
> You're actually using your shell's echo there.
> To use the coreutils one:
> 
>   env echo --help

Furthermore, the behavior you saw in your shell is required by POSIX.
If you do 'env POSIXLY_CORRECT=1 echo --help', you will get the same
behavior from coreutils as you did from your shell.  'echo' is one of
the few utilities that _cannot_ honor --help for compatibility reasons.


> Note newer versions of bash will support $builtin --help,
> though I've not tested the echo case which would
> introduce a change in behavior.

If bash changes the behavior of 'echo --help' in POSIX mode, then that
would be a bug in bash.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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Message #18 received at 19604 <at> debbugs.gnu.org (full text, mbox):

From: prateek goyal <prateek.goyal5 <at> gmail.com>
To: Eric Blake <eblake <at> redhat.com>
Cc: 19604 <at> debbugs.gnu.org, Pádraig Brady <P <at> draigbrady.com>
Subject: Re: bug#19604: echo --help does not work
Date: Thu, 15 Jan 2015 21:25:51 +0530

[Message part 1 (text/plain, inline)]

So even if I execute following command, it gives same result:

env POSIXLY_CORRECT=1 echo --help

prateek <at> prateek-pc:~/Documents/awk$ env POSIXLY_CORRECT=1 echo --help
--help

Thanks,
prateek

On 15 January 2015 at 19:39, Eric Blake <eblake <at> redhat.com> wrote:

> On 01/15/2015 04:36 AM, Pádraig Brady wrote:
> > tag 19604 notabug
> > close 19604
> > stop
> >
> > On 15/01/15 06:20, prateek goyal wrote:
> >> Hi,
> >>
> >>
> >> when I try to use --help option with echo command, it does not print
> help contents, but prints "--help".
> >>
> >>
> >> prateek <at> prateek-pc:~/Documents/awk$ echo --help
> >> --help
> >
> > You're actually using your shell's echo there.
> > To use the coreutils one:
> >
> >   env echo --help
>
> Furthermore, the behavior you saw in your shell is required by POSIX.
> If you do 'env POSIXLY_CORRECT=1 echo --help', you will get the same
> behavior from coreutils as you did from your shell.  'echo' is one of
> the few utilities that _cannot_ honor --help for compatibility reasons.
>
>
> > Note newer versions of bash will support $builtin --help,
> > though I've not tested the echo case which would
> > introduce a change in behavior.
>
> If bash changes the behavior of 'echo --help' in POSIX mode, then that
> would be a bug in bash.
>
> --
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
>
>


-- 

*Thanks,Prateek Goyal*

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Message #21 received at 19604 <at> debbugs.gnu.org (full text, mbox):

From: Bernhard Voelker <mail <at> bernhard-voelker.de>
To: prateek goyal <prateek.goyal5 <at> gmail.com>, Eric Blake <eblake <at> redhat.com>
Cc: 19604 <at> debbugs.gnu.org, Pádraig Brady <P <at> draigbrady.com>
Subject: Re: bug#19604: echo --help does not work
Date: Fri, 16 Jan 2015 10:49:06 +0100

On 01/15/2015 04:55 PM, prateek goyal wrote:
> So even if I execute following command, it gives same result:

> prateek <at> prateek-pc:~/Documents/awk$ env POSIXLY_CORRECT=1 echo --help
> --help

That is exactly what Eric said before: POSIX mandates to literally
output the string "--help" - which coreutils' echo does if the variable
POSIXLY_CORRECT is set.  Otherwise, the implementation extends the
functionality and adheres to GNU standards which mandates to honor
the "--help" option to output the usage message:

  $ env --unset=POSIXLY_CORRECT echo --help
  Usage: ...

Maybe you were confused by the use of the 'env' utility.
You'll get the same by specifying the echo with it's absolute path:

  $ which echo
  /usr/bin/echo
  $ unset POSIXLY_CORRECT
  $ /usr/bin/echo --help
  Usage: [...]

Have a nice day,
Berny

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