all messages for Emacs-related lists mirrored at yhetil.org
 help / color / mirror / code / Atom feed
* Why sh-set-shell insert a space after #!
@ 2012-08-17  4:05 Leo
  2012-08-17  5:22 ` Thierry Volpiatto
  2012-08-17  7:18 ` Stephen J. Turnbull
  0 siblings, 2 replies; 12+ messages in thread
From: Leo @ 2012-08-17  4:05 UTC (permalink / raw)
  To: emacs-devel

Hello all,

If you M-x sh-set-shell in a buffer it inserts something like:

  #! /bin/bash

I am curious why a space after #!. I read this page:
http://en.wikipedia.org/wiki/Shebang_(Unix). The newsgroup post by
Dennis Ritchie also has a space. But most scripts I have seen do not. So
I am curious ;)

Leo




^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: Why sh-set-shell insert a space after #!
  2012-08-17  4:05 Why sh-set-shell insert a space after #! Leo
@ 2012-08-17  5:22 ` Thierry Volpiatto
  2012-08-17  6:54   ` Leo
  2012-08-24 17:08   ` Aurélien Aptel
  2012-08-17  7:18 ` Stephen J. Turnbull
  1 sibling, 2 replies; 12+ messages in thread
From: Thierry Volpiatto @ 2012-08-17  5:22 UTC (permalink / raw)
  To: emacs-devel

Leo <sdl.web@gmail.com> writes:

> Hello all,
>
> If you M-x sh-set-shell in a buffer it inserts something like:
>
>   #! /bin/bash
>
> I am curious why a space after #!. I read this page:
> http://en.wikipedia.org/wiki/Shebang_(Unix). The newsgroup post by
> Dennis Ritchie also has a space. But most scripts I have seen do not. So
> I am curious ;)
Seems that this is wrong:
http://en.wikipedia.org/wiki/Shebang_%28Unix%29#Magic_number
http://www.in-ulm.de/~mascheck/various/shebang/#details


-- 
  Thierry
Get my Gnupg key:
gpg --keyserver pgp.mit.edu --recv-keys 59F29997 




^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: Why sh-set-shell insert a space after #!
  2012-08-17  5:22 ` Thierry Volpiatto
@ 2012-08-17  6:54   ` Leo
  2012-08-17  7:06     ` Leo
  2012-08-24 17:08   ` Aurélien Aptel
  1 sibling, 1 reply; 12+ messages in thread
From: Leo @ 2012-08-17  6:54 UTC (permalink / raw)
  To: Thierry Volpiatto; +Cc: emacs-devel

On 2012-08-17 13:22 +0800, Thierry Volpiatto wrote:
> Seems that this is wrong:
> http://en.wikipedia.org/wiki/Shebang_%28Unix%29#Magic_number
> http://www.in-ulm.de/~mascheck/various/shebang/#details

Have I just discovered one of the oldest bugs? ;)

Leo



^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: Why sh-set-shell insert a space after #!
  2012-08-17  6:54   ` Leo
@ 2012-08-17  7:06     ` Leo
  2012-08-22 17:17       ` Bastien
  0 siblings, 1 reply; 12+ messages in thread
From: Leo @ 2012-08-17  7:06 UTC (permalink / raw)
  To: Chong Yidong; +Cc: Thierry Volpiatto, emacs-devel

On 2012-08-17 14:54 +0800, Leo wrote:
>> Seems that this is wrong:
>> http://en.wikipedia.org/wiki/Shebang_%28Unix%29#Magic_number
>> http://www.in-ulm.de/~mascheck/various/shebang/#details
>
> Have I just discovered one of the oldest bugs? ;)

Hello Yidong,

Any objection to installing this tiny patch in emacs-24?

diff --git a/lisp/progmodes/executable.el b/lisp/progmodes/executable.el
index c44f1d73..201b4797 100644
--- a/lisp/progmodes/executable.el
+++ b/lisp/progmodes/executable.el
@@ -84,8 +84,9 @@ (defcustom executable-magicless-file-regexp "/[Mm]akefile$\\|/\\.\\(z?profile\\|
   :group 'executable)
 
 
-(defcustom executable-prefix "#! "
+(defcustom executable-prefix "#!"
   "*Interpreter magic number prefix inserted when there was no magic number."
+  :version "24.2"
   :type 'string
   :group 'executable)
 



^ permalink raw reply related	[flat|nested] 12+ messages in thread

* Why sh-set-shell insert a space after #!
  2012-08-17  4:05 Why sh-set-shell insert a space after #! Leo
  2012-08-17  5:22 ` Thierry Volpiatto
@ 2012-08-17  7:18 ` Stephen J. Turnbull
  2012-08-17  8:05   ` Andreas Schwab
  2012-08-17 15:50   ` Leo
  1 sibling, 2 replies; 12+ messages in thread
From: Stephen J. Turnbull @ 2012-08-17  7:18 UTC (permalink / raw)
  To: Leo; +Cc: emacs-devel

Leo writes:
 > Hello all,
 > 
 > If you M-x sh-set-shell in a buffer it inserts something like:
 > 
 >   #! /bin/bash
 > 
 > I am curious why a space after #!. I read this page:
 > http://en.wikipedia.org/wiki/Shebang_(Unix). The newsgroup post by
 > Dennis Ritchie also has a space. But most scripts I have seen do not. So
 > I am curious ;)

IIRC, POSIX allows but doesn't require the space.  However, some
historical mostly-compatible shells had problems if there was no
space.  Since it never hurts with fully conforming shells, and
sometimes helps, it's a definite portability win.  (AFAIK there was no
particular correlation between this kind of non-conformance and other,
more important, non-conformance.)

Although it's not needed for bash, you can argue for it from
simplicity of sh-mode implementation (you don't need to detect the
shell and maintain a list of which shells care to decide whether to
insert the space) and consistency of style.



^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: Why sh-set-shell insert a space after #!
  2012-08-17  7:18 ` Stephen J. Turnbull
@ 2012-08-17  8:05   ` Andreas Schwab
  2012-08-17 15:50   ` Leo
  1 sibling, 0 replies; 12+ messages in thread
From: Andreas Schwab @ 2012-08-17  8:05 UTC (permalink / raw)
  To: Stephen J. Turnbull; +Cc: Leo, emacs-devel

"Stephen J. Turnbull" <stephen@xemacs.org> writes:

> IIRC, POSIX allows but doesn't require the space.  However, some
> historical mostly-compatible shells had problems if there was no
> space.

There is some background information in
<http://www.in-ulm.de/~mascheck/various/shebang/#blankrequired>.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."



^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: Why sh-set-shell insert a space after #!
  2012-08-17  7:18 ` Stephen J. Turnbull
  2012-08-17  8:05   ` Andreas Schwab
@ 2012-08-17 15:50   ` Leo
  2012-08-17 16:37     ` Thierry Volpiatto
  1 sibling, 1 reply; 12+ messages in thread
From: Leo @ 2012-08-17 15:50 UTC (permalink / raw)
  To: Stephen J. Turnbull; +Cc: emacs-devel

On 2012-08-17 15:18 +0800, Stephen J. Turnbull wrote:
> IIRC, POSIX allows but doesn't require the space.  However, some
> historical mostly-compatible shells had problems if there was no
> space.  Since it never hurts with fully conforming shells, and
> sometimes helps, it's a definite portability win.  (AFAIK there was no
> particular correlation between this kind of non-conformance and other,
> more important, non-conformance.)

From my reading of the two links, separation #! and the path with a
space is abnormal and evidenced by all scripts I can find. So I think
the better default for executable-prefix is "#!", not "#! ".

Leo



^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: Why sh-set-shell insert a space after #!
  2012-08-17 15:50   ` Leo
@ 2012-08-17 16:37     ` Thierry Volpiatto
  0 siblings, 0 replies; 12+ messages in thread
From: Thierry Volpiatto @ 2012-08-17 16:37 UTC (permalink / raw)
  To: emacs-devel

Leo <sdl.web@gmail.com> writes:

> On 2012-08-17 15:18 +0800, Stephen J. Turnbull wrote:
>> IIRC, POSIX allows but doesn't require the space.  However, some
>> historical mostly-compatible shells had problems if there was no
>> space.  Since it never hurts with fully conforming shells, and
>> sometimes helps, it's a definite portability win.  (AFAIK there was no
>> particular correlation between this kind of non-conformance and other,
>> more important, non-conformance.)
>
> From my reading of the two links, separation #! and the path with a
> space is abnormal and evidenced by all scripts I can find. So I think
> the better default for executable-prefix is "#!", not "#! ".
Agree, also in all books, manuals I found , it is described like "#!/bin/bash"
and never "#! /bin/bash", same for python.

-- 
  Thierry
Get my Gnupg key:
gpg --keyserver pgp.mit.edu --recv-keys 59F29997 




^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: Why sh-set-shell insert a space after #!
  2012-08-17  7:06     ` Leo
@ 2012-08-22 17:17       ` Bastien
  2012-08-23  0:53         ` Leo
  0 siblings, 1 reply; 12+ messages in thread
From: Bastien @ 2012-08-22 17:17 UTC (permalink / raw)
  To: Leo; +Cc: Chong Yidong, emacs-devel, Thierry Volpiatto

Leo <sdl.web@gmail.com> writes:

> Any objection to installing this tiny patch in emacs-24?

I read the links and I also think the default should be "#!".

I just applied Leo's patch.

-- 
 Bastien



^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: Why sh-set-shell insert a space after #!
  2012-08-22 17:17       ` Bastien
@ 2012-08-23  0:53         ` Leo
  2012-08-23  9:54           ` Bastien
  0 siblings, 1 reply; 12+ messages in thread
From: Leo @ 2012-08-23  0:53 UTC (permalink / raw)
  To: Bastien; +Cc: Chong Yidong, Thierry Volpiatto, emacs-devel

On 2012-08-23 01:17 +0800, Bastien wrote:
> I just applied Leo's patch.

Thanks. I wonder if a :version "24.3" is needed? ;)

Leo



^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: Why sh-set-shell insert a space after #!
  2012-08-23  0:53         ` Leo
@ 2012-08-23  9:54           ` Bastien
  0 siblings, 0 replies; 12+ messages in thread
From: Bastien @ 2012-08-23  9:54 UTC (permalink / raw)
  To: Leo; +Cc: Chong Yidong, emacs-devel, Thierry Volpiatto

Leo <sdl.web@gmail.com> writes:

> On 2012-08-23 01:17 +0800, Bastien wrote:
>> I just applied Leo's patch.
>
> Thanks. I wonder if a :version "24.3" is needed? ;)

Yep.  Already done.

-- 
 Bastien



^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: Why sh-set-shell insert a space after #!
  2012-08-17  5:22 ` Thierry Volpiatto
  2012-08-17  6:54   ` Leo
@ 2012-08-24 17:08   ` Aurélien Aptel
  1 sibling, 0 replies; 12+ messages in thread
From: Aurélien Aptel @ 2012-08-24 17:08 UTC (permalink / raw)
  To: Thierry Volpiatto; +Cc: emacs-devel

On Fri, Aug 17, 2012 at 7:22 AM, Thierry Volpiatto
<thierry.volpiatto@gmail.com> wrote:
> Seems that this is wrong:
> http://en.wikipedia.org/wiki/Shebang_%28Unix%29#Magic_number
> http://www.in-ulm.de/~mascheck/various/shebang/#details

That was an interesting read, thank you.



^ permalink raw reply	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2012-08-24 17:08 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2012-08-17  4:05 Why sh-set-shell insert a space after #! Leo
2012-08-17  5:22 ` Thierry Volpiatto
2012-08-17  6:54   ` Leo
2012-08-17  7:06     ` Leo
2012-08-22 17:17       ` Bastien
2012-08-23  0:53         ` Leo
2012-08-23  9:54           ` Bastien
2012-08-24 17:08   ` Aurélien Aptel
2012-08-17  7:18 ` Stephen J. Turnbull
2012-08-17  8:05   ` Andreas Schwab
2012-08-17 15:50   ` Leo
2012-08-17 16:37     ` Thierry Volpiatto

Code repositories for project(s) associated with this external index

	https://git.savannah.gnu.org/cgit/emacs.git
	https://git.savannah.gnu.org/cgit/emacs/org-mode.git

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.