GNU bug report logs - #29617
seq: `seq 1 --help' doesn't give help

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

From: chadweisman <at> nym.hush.com
To: bug-coreutils <at> gnu.org
Subject: `seq 1 --help' doesn't give help
Date: Fri, 08 Dec 2017 12:38:23 -0500

Hello,

I am using coreutils version 8.27 on Fedora, and I don't see this fixed in 8.28's NEWS.

$ seq 1 --help
seq: invalid floating point argument: ‘--help’
Try 'seq --help' for more information.

We should be able to put the options anywhere and not necessarily before any arguments.  And even if not (e.g. POSIX conformance overrides,) --help should be handled specially to conform to the GNU coding standards. [1]

1. https://www.gnu.org/prep/standards/standards.html#g_t_002d_002dhelp

cheers,

Chad.

Message #8 received at 29617 <at> debbugs.gnu.org (full text, mbox):

From: Eric Blake <eblake <at> redhat.com>
To: chadweisman <at> nym.hush.com, 29617 <at> debbugs.gnu.org
Subject: Re: bug#29617: `seq 1 --help' doesn't give help
Date: Fri, 8 Dec 2017 12:55:04 -0600

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

On 12/08/2017 11:38 AM, chadweisman <at> nym.hush.com wrote:
> Hello,
> 
> I am using coreutils version 8.27 on Fedora, and I don't see this fixed in 8.28's NEWS.
> 
> $ seq 1 --help
> seq: invalid floating point argument: ‘--help’
> Try 'seq --help' for more information.

Interesting bug!

> 
> We should be able to put the options anywhere and not necessarily before any arguments.

Yes, when possible.

>  And even if not (e.g. POSIX conformance overrides,)

POSIX does say you have to write 'foo -- --help' if you want to
guarantee that --help is treated as a literal argument rather than
option, but it also says that the moment you specify '--help' (or any
other parameter starting with two dashes without the -- end-of-options
parameter), you are already in undefined territory.  So we can do
whatever we want when encountering '--help' - which is part of the
reason WHY the GNU project prefers making 'foo args --help' print help
output where possible.

> --help should be handled specially to conform to the GNU coding standards. [1]

Yes.

But the reason that it fails is because we use getopt_long(...,
"+f:s:w") - where the leading '+' specifically requests that we NOT
allow option reordering.  Why? Because 'seq' is MOST useful if it can
parse negative numbers easily.  We deemed it more important to support
'seq 2 -1 1' without requiring the user to write 'seq -- 2 -1 1' - but
in doing so, it also means that we can't reorder options, so any obvious
non-option (like '1' in your example) makes all other parameters
non-options (including '--help' in your example).

It might be possible to do a two-pass parse over argv: one that looks
just for --help (and where treating -1 as an option is a no-op), and the
second that actually parses things in order now that it knows --help is
not present.  But that's a lot of code to add for a corner case, so I
won't be writing the patch; but I also won't turn it down if someone
else wants to write the patch.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

[signature.asc (application/pgp-signature, attachment)]

Message #11 received at submit <at> debbugs.gnu.org (full text, mbox):

From: chadweisman <at> nym.hush.com
To: bug-coreutils <at> gnu.org
Subject: Re: bug#29617: `seq 1 --help' doesn't give help
Date: Sun, 18 Feb 2018 13:41:25 -0500

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

> On 12/08/2017 11:38 AM, Eric B wrote:
> > Hello,
> > 
> > I am using coreutils version 8.27 on Fedora, and I don't see this fixed in 
> > 8.28's NEWS.
> > 
> > $ seq 1 --help
> > seq: invalid floating point argument: ‘--help’
> > Try 'seq --help' for more information.

> Interesting bug!

> > 
> > We should be able to put the options anywhere and not necessarily before any 
> > arguments.

> Yes, when possible.

> > And even if not (e.g. POSIX conformance overrides,)

> POSIX does say you have to write 'foo -- --help' if you want to
> guarantee that --help is treated as a literal argument rather than
> option, but it also says that the moment you specify '--help' (or any
> other parameter starting with two dashes without the -- end-of-options
> parameter), you are already in undefined territory.  So we can do
> whatever we want when encountering '--help' - which is part of the
> reason WHY the GNU project prefers making 'foo args --help' print help
> output where possible.

> > --help should be handled specially to conform to the GNU coding standards. [1]

> Yes.

> But the reason that it fails is because we use getopt_long(...,
> "+f:s:w") - where the leading '+' specifically requests that we NOT
> allow option reordering.  Why? Because 'seq' is MOST useful if it can
> parse negative numbers easily.  We deemed it more important to support
> 'seq 2 -1 1' without requiring the user to write 'seq -- 2 -1 1' - but
> in doing so, it also means that we can't reorder options, so any obvious
> non-option (like '1' in your example) makes all other parameters
> non-options (including '--help' in your example).

> It might be possible to do a two-pass parse over argv: one that looks
> just for --help (and where treating -1 as an option is a no-op), and the
> second that actually parses things in order now that it knows --help is
> not present.  But that's a lot of code to add for a corner case, so I
> won't be writing the patch; but I also won't turn it down if someone
> else wants to write the patch.

Hello,

I've taken a stab at fixing this problem because it affects me fairly often.

Instead of using a two-pass system, I check if any of the args we scan are --help or --version and bail if we see either.  See attached patch.

The bad side of this approach is that the -f, -s, and -w options and their associated long options aren't handled so `seq 1 -w 2 10` still shows an error.  Also, it's a kludgy sort of fix, so I completely understand why you wouldn't want to include it.  But at least it's a step in the right direction to give help when we can instead of an error.

Chad

[coreutils-seq-bug-29617.patch (application/octet-stream, attachment)]

Message #14 received at 29617 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: chadweisman <at> nym.hush.com, 29617 <at> debbugs.gnu.org
Subject: Re: bug#29617: `seq 1 --help' doesn't give help
Date: Mon, 19 Feb 2018 17:35:03 -0800

On 18/02/18 10:41, chadweisman <at> nym.hush.com wrote:
> 
>> On 12/08/2017 11:38 AM, Eric B wrote:
>>> Hello,
>>>
>>> I am using coreutils version 8.27 on Fedora, and I don't see this fixed in 
>>> 8.28's NEWS.
>>>
>>> $ seq 1 --help
>>> seq: invalid floating point argument: ‘--help’
>>> Try 'seq --help' for more information.
> 
>> Interesting bug!
> 
>>>
>>> We should be able to put the options anywhere and not necessarily before any 
>>> arguments.
> 
>> Yes, when possible.
> 
>>> And even if not (e.g. POSIX conformance overrides,)
> 
>> POSIX does say you have to write 'foo -- --help' if you want to
>> guarantee that --help is treated as a literal argument rather than
>> option, but it also says that the moment you specify '--help' (or any
>> other parameter starting with two dashes without the -- end-of-options
>> parameter), you are already in undefined territory.  So we can do
>> whatever we want when encountering '--help' - which is part of the
>> reason WHY the GNU project prefers making 'foo args --help' print help
>> output where possible.
> 
>>> --help should be handled specially to conform to the GNU coding standards. [1]
> 
>> Yes.
> 
>> But the reason that it fails is because we use getopt_long(...,
>> "+f:s:w") - where the leading '+' specifically requests that we NOT
>> allow option reordering.  Why? Because 'seq' is MOST useful if it can
>> parse negative numbers easily.  We deemed it more important to support
>> 'seq 2 -1 1' without requiring the user to write 'seq -- 2 -1 1' - but
>> in doing so, it also means that we can't reorder options, so any obvious
>> non-option (like '1' in your example) makes all other parameters
>> non-options (including '--help' in your example).
> 
>> It might be possible to do a two-pass parse over argv: one that looks
>> just for --help (and where treating -1 as an option is a no-op), and the
>> second that actually parses things in order now that it knows --help is
>> not present.  But that's a lot of code to add for a corner case, so I
>> won't be writing the patch; but I also won't turn it down if someone
>> else wants to write the patch.
> 
> Hello,
> 
> I've taken a stab at fixing this problem because it affects me fairly often.
> 
> Instead of using a two-pass system, I check if any of the args we scan are --help or --version and bail if we see either.  See attached patch.
> 
> The bad side of this approach is that the -f, -s, and -w options and their associated long options aren't handled so `seq 1 -w 2 10` still shows an error.  Also, it's a kludgy sort of fix, so I completely understand why you wouldn't want to include it.  But at least it's a step in the right direction to give help when we can instead of an error.
> 
> Chad
> 

Thanks for looking at this again.
You attached the wrong patch.

A helper function to prescan argv to look for --help and call usage()
or --version and call version_etc(), while bailing itself
if it encounters '--', does seem useful to have in seq.
Though note it probably shouldn't support abbreviations like --h etc.

BTW other commands that use '+' with getopt() to exist option
processing early are tr, basename, pathchk, printf.
Though all those could interpret --option as a valid argument
and so wouldn't be appropriate to treat like this.
Likewise for all the commands the exec, like chroot, env, ...
as --options are very often passed to the delegate commands.

cheers,
Pádraig.

Message #17 received at submit <at> debbugs.gnu.org (full text, mbox):

From: chadweisman <at> nym.hush.com
To: "Pádraig Brady" <p <at> draigbrady.com>,
 bug-coreutils <at> gnu.org
Subject: Re: bug#29617: `seq 1 --help' doesn't give help
Date: Mon, 19 Feb 2018 20:42:44 -0500

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

On 2/19/2018 at 8:35 PM, "Pádraig Brady" <P <at> draigBrady.com> wrote:
>
>On 18/02/18 10:41, chadweisman <at> nym.hush.com wrote:
>> 
>>> On 12/08/2017 11:38 AM, Eric B wrote:
>>>> Hello,
>>>>
>>>> I am using coreutils version 8.27 on Fedora, and I don't see 
>this fixed in 
>>>> 8.28's NEWS.
>>>>
>>>> $ seq 1 --help
>>>> seq: invalid floating point argument: ‘--help’
>>>> Try 'seq --help' for more information.
>> 
>>> Interesting bug!
>> 
>>>>
>>>> We should be able to put the options anywhere and not 
>necessarily before any 
>>>> arguments.
>> 
>>> Yes, when possible.
>> 
>>>> And even if not (e.g. POSIX conformance overrides,)
>> 
>>> POSIX does say you have to write 'foo -- --help' if you want to
>>> guarantee that --help is treated as a literal argument rather 
>than
>>> option, but it also says that the moment you specify '--help' 
>(or any
>>> other parameter starting with two dashes without the -- end-of-
>options
>>> parameter), you are already in undefined territory.  So we can 
>do
>>> whatever we want when encountering '--help' - which is part of 
>the
>>> reason WHY the GNU project prefers making 'foo args --help' 
>print help
>>> output where possible.
>> 
>>>> --help should be handled specially to conform to the GNU 
>coding standards. [1]
>> 
>>> Yes.
>> 
>>> But the reason that it fails is because we use getopt_long(...,
>>> "+f:s:w") - where the leading '+' specifically requests that we 
>NOT
>>> allow option reordering.  Why? Because 'seq' is MOST useful if 
>it can
>>> parse negative numbers easily.  We deemed it more important to 
>support
>>> 'seq 2 -1 1' without requiring the user to write 'seq -- 2 -1 
>1' - but
>>> in doing so, it also means that we can't reorder options, so 
>any obvious
>>> non-option (like '1' in your example) makes all other parameters
>>> non-options (including '--help' in your example).
>> 
>>> It might be possible to do a two-pass parse over argv: one that 
>looks
>>> just for --help (and where treating -1 as an option is a no-
>op), and the
>>> second that actually parses things in order now that it knows --
>help is
>>> not present.  But that's a lot of code to add for a corner 
>case, so I
>>> won't be writing the patch; but I also won't turn it down if 
>someone
>>> else wants to write the patch.
>> 
>> Hello,
>> 
>> I've taken a stab at fixing this problem because it affects me 
>fairly often.
>> 
>> Instead of using a two-pass system, I check if any of the args 
>we scan are --help or --version and bail if we see either.  See 
>attached patch.
>> 
>> The bad side of this approach is that the -f, -s, and -w options 
>and their associated long options aren't handled so `seq 1 -w 2 
>10` still shows an error.  Also, it's a kludgy sort of fix, so I 
>completely understand why you wouldn't want to include it.  But at 
>least it's a step in the right direction to give help when we can 
>instead of an error.
>> 
>> Chad
>> 
>
>Thanks for looking at this again.
>You attached the wrong patch.
>

Wow, did I ever!  Sorry for that.

>A helper function to prescan argv to look for --help and call 
>usage()
>or --version and call version_etc(), while bailing itself
>if it encounters '--', does seem useful to have in seq.
>Though note it probably shouldn't support abbreviations like --h 
>etc.
>
>BTW other commands that use '+' with getopt() to exist option
>processing early are tr, basename, pathchk, printf.
>Though all those could interpret --option as a valid argument
>and so wouldn't be appropriate to treat like this.
>Likewise for all the commands the exec, like chroot, env, ...
>as --options are very often passed to the delegate commands.
>

I also tried a two-pass approach but it ended up being pretty messy.  I can't help but think using argp would make this particular problem easier to handle.

Chad

[coreutils-seq.patch (application/octet-stream, attachment)]

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