bug#68583: 29.1; Can't find the cat manpage

bug#68583: 29.1; Can't find the cat manpage

[Christopher Yeleighton]

M-x man RET cat RET

Can't find the cat manpage



In GNU Emacs 29.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.38,
cairo version 1.17.8)
Windowing system distributor 'The X.Org Foundation', version 11.0.12101010
System Description: Arch Linux

Configured using:
'configure --sysconfdir=/etc --prefix=/usr --libexecdir=/usr/lib
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--disable-build-details --with-harfbuzz --with-libsystemd
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'LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -flto=auto''

Configured features:
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value of $LANG: pl_PL.UTF-8
locale-coding-system: utf-8-unix

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Load-path shadows:
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bug#68583: 29.1; Can't find the cat manpage

[Manuel Giraud via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Christopher Yeleighton <giecrilj@stegny.2a.pl> writes:

> M-x man RET cat RET
>
> Can't find the cat manpage

Hi,

Have you try it starting with emacs -Q?
-- 
Manuel Giraud

bug#68583: 29.1; Can't find the cat manpage

[Christopher Yeleighton]

The problem is MANOPT=-X100-12.  Emacs cannot handle this config.

On 19.01.2024 10:28, Manuel Giraud wrote:
> Christopher Yeleighton <giecrilj@stegny.2a.pl> writes:
>
>> M-x man RET cat RET
>>
>> Can't find the cat manpage
> Hi,
>
> Have you try it starting with emacs -Q?

bug#68583: 29.1; Can't find the cat manpage

[Manuel Giraud via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Christopher Yeleighton <giecrilj@stegny.2a.pl> writes:

> The problem is MANOPT=-X100-12.  Emacs cannot handle this config.

Ok.  So you want to read man with an external viewer?
-- 
Manuel Giraud

bug#68583: 29.1; Can't find the cat manpage

[Christopher Yeleighton]

gxditview display is more accurate (most of the time) but it cannot mark 
text, so it depends on the content.  Emacs could just unset MANOPT as 
far as I am concerned.

On 19.01.2024 10:40, Manuel Giraud wrote:
> Christopher Yeleighton <giecrilj@stegny.2a.pl> writes:
>
>> The problem is MANOPT=-X100-12.  Emacs cannot handle this config.
> Ok.  So you want to read man with an external viewer?

bug#68583: 29.1; Can't find the cat manpage

[Eli Zaretskii]

> Cc: 68583@debbugs.gnu.org
> Date: Fri, 19 Jan 2024 10:44:18 +0000
> From: Christopher Yeleighton <giecrilj@stegny.2a.pl>
> 
> gxditview display is more accurate (most of the time) but it cannot mark 
> text, so it depends on the content.  Emacs could just unset MANOPT as 
> far as I am concerned.

Emacs cannot just unset MANOPT, since that variable could specify
command-line options for the 'man' command other than the ones you
used.

To avoid the problem you describe, I suggest to set MANOPT only in the
init file of interactive shell, so that a non-interactive shell
invoked by Emacs to run shell commands will be unaffected by MANOPT.

I don't think this is an Emacs bug.

bug#68583: 29.1; Can't find the cat manpage

[Christopher Yeleighton]

In that case, the error message emitted by Emacs is wrong.  Emacs 
assumes that the man process failed for a particular reason, which is 
not the case.

On 19.01.2024 12:01, Eli Zaretskii wrote:
>> Cc: 68583@debbugs.gnu.org
>> Date: Fri, 19 Jan 2024 10:44:18 +0000
>> From: Christopher Yeleighton <giecrilj@stegny.2a.pl>
>>
>> gxditview display is more accurate (most of the time) but it cannot mark
>> text, so it depends on the content.  Emacs could just unset MANOPT as
>> far as I am concerned.
> Emacs cannot just unset MANOPT, since that variable could specify
> command-line options for the 'man' command other than the ones you
> used.
>
> To avoid the problem you describe, I suggest to set MANOPT only in the
> init file of interactive shell, so that a non-interactive shell
> invoked by Emacs to run shell commands will be unaffected by MANOPT.
>
> I don't think this is an Emacs bug.

bug#68583: 29.1; Can't find the cat manpage

[Eli Zaretskii]

> Date: Fri, 19 Jan 2024 12:05:03 +0000
> Cc: manuel@ledu-giraud.fr, 68583@debbugs.gnu.org
> From: Christopher Yeleighton <giecrilj@stegny.2a.pl>
> 
> In that case, the error message emitted by Emacs is wrong.  Emacs 
> assumes that the man process failed for a particular reason, which is 
> not the case.

What is the error message, and why do you think it's wrong?

What would be the right error message in this case?

bug#68583: 29.1; Can't find the cat manpage

[Christopher Yeleighton]

The error message is literally:

 > Can't find the cat manpage

This is the title of this bug report, BTW ;-)

The right error message would be:

 > Emacs cannot display the cat manpage, either because it cannot be 
found or because it cannot be rendered.  Try using the command ... to 
diagnose the problem!

Troubleshooting instructions could be included in the mode documentation 
instead.

On 19.01.2024 12:06, Eli Zaretskii wrote:
>> Date: Fri, 19 Jan 2024 12:05:03 +0000
>> Cc: manuel@ledu-giraud.fr, 68583@debbugs.gnu.org
>> From: Christopher Yeleighton <giecrilj@stegny.2a.pl>
>>
>> In that case, the error message emitted by Emacs is wrong.  Emacs
>> assumes that the man process failed for a particular reason, which is
>> not the case.
> What is the error message, and why do you think it's wrong?
>
> What would be the right error message in this case?

bug#68583: 29.1; Can't find the cat manpage

[Eli Zaretskii]

severity 68583 wishlist
thanks

> Date: Fri, 19 Jan 2024 12:17:08 +0000
> Cc: manuel@ledu-giraud.fr, 68583@debbugs.gnu.org
> From: Christopher Yeleighton <giecrilj@stegny.2a.pl>
> 
> The error message is literally:
> 
>  > Can't find the cat manpage
> 
> This is the title of this bug report, BTW ;-)

Yes, but it was not clear from the report that it is also the text of
the error message you see.  Thus my question.

> The right error message would be:
> 
>  > Emacs cannot display the cat manpage, either because it cannot be 
> found or because it cannot be rendered.  Try using the command ... to 
> diagnose the problem!

But that's not what happened.  man.el actually tries to find the man
page by itself, and displays that message if it fails.

> Troubleshooting instructions could be included in the mode documentation 
> instead.

Patches to make the diagnostic smarter in this case, including
figuring out what to use instead of "..." above, are welcome.

bug#68583: 29.1; Can't find the cat manpage

[Christopher Yeleighton]

If the code in man.el tried to find the manual page by itself, it would 
not fail because the manual page is there. It succeeds if MANOPT is not 
set and my MANOPT should not affect the manual page search algorithm.

On 19.01.2024 12:41, Eli Zaretskii wrote:
> But that's not what happened.  man.el actually tries to find the man
> page by itself, and displays that message if it fails.
>

bug#68583: 29.1; Can't find the cat manpage

[Eli Zaretskii]

> Date: Fri, 19 Jan 2024 12:46:57 +0000
> Cc: manuel@ledu-giraud.fr, 68583@debbugs.gnu.org
> From: Christopher Yeleighton <giecrilj@stegny.2a.pl>
> 
> If the code in man.el tried to find the manual page by itself, it would 
> not fail because the manual page is there. It succeeds if MANOPT is not 
> set and my MANOPT should not affect the manual page search algorithm.

That depends on how we try to find the manual page(s).  The
implementation calls 'man' in a special way, which evidently fails
under the value of MANOPT you set.

bug#68583: 29.1; Can't find the cat manpage

[Christopher Yeleighton]

[-- Attachment #1: Type: text/plain, Size: 960 bytes --]

M-x setenv RET MANOPT RET -X100-12 RET M-x man RET man RET

This command shows the manual page for man in a new gxditview window. 
Emacs cannot display the manual page because it has not been rendered to 
text. But the error message is "Can't find the cat manpage". The message 
is wrong. Emacs did not try to find the cat manpage, it tried to 
retrieve it and it did not work.

On 19.01.2024 14:32, Eli Zaretskii wrote:
>> Date: Fri, 19 Jan 2024 12:46:57 +0000
>> Cc:manuel@ledu-giraud.fr,68583@debbugs.gnu.org
>> From: Christopher Yeleighton<giecrilj@stegny.2a.pl>
>>
>> If the code in man.el tried to find the manual page by itself, it would
>> not fail because the manual page is there. It succeeds if MANOPT is not
>> set and my MANOPT should not affect the manual page search algorithm.
> That depends on how we try to find the manual page(s).  The
> implementation calls 'man' in a special way, which evidently fails
> under the value of MANOPT you set.

[-- Attachment #2: Type: text/html, Size: 1704 bytes --]

bug#68583: 29.1; Can't find the cat manpage

[Christopher Yeleighton]

M-x setenv RET MANOPT RET -X100-12 RET M-x man RET man RET

This command shows the manual page for man in a new gxditview window.
Emacs cannot display the manual page because it has not been rendered to
text. But the error message is "Can't find the man manpage". The message
is wrong. Emacs did not try to find the man manpage, it tried to
retrieve it and it did not work.

On 19.01.2024 14:32, Eli Zaretskii wrote:
>> Date: Fri, 19 Jan 2024 12:46:57 +0000
>> Cc: manuel@ledu-giraud.fr, 68583@debbugs.gnu.org
>> From: Christopher Yeleighton <giecrilj@stegny.2a.pl>
>>
>> If the code in man.el tried to find the manual page by itself, it would
>> not fail because the manual page is there. It succeeds if MANOPT is not
>> set and my MANOPT should not affect the manual page search algorithm.
> That depends on how we try to find the manual page(s).  The
> implementation calls 'man' in a special way, which evidently fails
> under the value of MANOPT you set.