[TUHS] TUHS Digest, Vol 33, Issue 7
Don Hopkins
don at DonHopkins.com
Wed Aug 8 22:10:32 AEST 2018
Decades ago I made my prompt simply end with a newline, which perfectly and cleanly solves the problem of making it easy to copy and paste a whole line by multiple clicking in a terminal emulator to select the line, or by using line oriented commands in an emacs shell (or moving to the line and hitting return, which Emacs often regularly fucks up with its idiotic kludges to identify the prompt with invisible marks and regular expressions), without injecting any garbage characters into the beginning of the command line or requiring any extra mouse clicks, precision cursor targeting, or extra keystrokes.
Using “;” or any other character as a prompt is an ugly hack, and doesn’t solve the problem thoroughly or cleanly. No matter what character you use as a prompt at the beginning of the line, it’s going to cause some problems, like semicolons building up each time you re-enter the line, or conflicts with built-in shell syntax (retch!), so the only logical (and most obvious) solution is not to use any characters at the beginning of the line at all, and just put the prompt on a line above on its own. There is no downside to that, unless it somehow offends your sense of aesthetics. (In which case you should get over it.)
That’s the cleanest solution without any unpleasant side effects. I don’t understand why that solution isn’t the first thing shell users think of, and the default used by the shell — it’s so obvious. Maybe because people used to the shell are just so accustomed to having to deal with mashing together unpleasant hackey kludgy incompatible competing ad-hoc syntax that it would never occur to them that it’s possible to solve a problem by REMOVING punctuation and noise characters instead of ADDING more of them.
-Don
> On 8 Aug 2018, at 04:00, tuhs-request at minnie.tuhs.org wrote:
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> Today's Topics:
>
> 1. Re: Origins of shell prompt suffixes % $ > # (Michael Kjörling)
> 2. Re: Origins of shell prompt suffixes % $ > # (Kurt H Maier)
> 3. Re: Origins of shell prompt suffixes % $ > # (arnold at skeeve.com)
> 4. Re: Origins of shell prompt suffixes % $ > # (Bakul Shah)
> 5. Re: Origins of shell prompt suffixes % $ > # (Michael Kjörling)
> 6. Re: Origins of shell prompt suffixes % $ > # (Dave Horsfall)
> 7. Re: Origins of shell prompt suffixes % $ > # (KatolaZ)
> 8. Re: TUHS Digest, Vol 33, Issue 5 (Steve Johnson)
> 9. Re: Origins of shell prompt suffixes % $ > # (Tony Finch)
> 10. Re: Origins of shell prompt suffixes % $ > # (Pete Turnbull)
> 11. Re: Origins of shell prompt suffixes % $ > # (Doug McIlroy)
> 12. Re: Origins of shell prompt suffixes % $ > # (Brian Zick)
> 13. Re: Origins of shell prompt suffixes % $ > # (John P. Linderman)
> 14. Re: Origins of shell prompt suffixes % $ > # (Lyndon Nerenberg)
> 15. Re: Origins of shell prompt suffixes % $ > # (Cág)
> 16. Re: Origins of shell prompt suffixes % $ > # (arnold at skeeve.com)
> 17. Re: Origins of shell prompt suffixes % $ > # (Cág)
> 18. Re: Origins of shell prompt suffixes % $ > # (Brian Zick)
>
> From: Michael Kjörling <michael at kjorling.se>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 08:54:54 CEST
> To: tuhs at minnie.tuhs.org
>
>
> On 6 Aug 2018 21:53 +0100, from brian at zick.io (Brian Zick):
>> rc uses ;
>
> Not sure what came first, and not up to digging out the history books,
> but these days, a plain `;` for a prompt has a distinct advantage in
> that you can copy the whole line and paste it into another shell, and
> the shell will do The Right Thing (tm) as long as (as is, I believe,
> done by all of the major shells at least) it uses `;` for command
> separation.
>
> --
> Michael Kjörling • https://michael.kjorling.se • michael at kjorling.se
> “The most dangerous thought that you can have as a creative person
> is to think you know what you’re doing.” (Bret Victor)
>
>
>
>
> From: Kurt H Maier <khm at sciops.net>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 09:31:36 CEST
> To: Brian Zick <brian at zick.io>
> Cc: tuhs at minnie.tuhs.org
>
>
> On Mon, Aug 06, 2018 at 09:53:33PM +0100, Brian Zick wrote:
>>
>> rc uses ;
>
> Does it? 10th edition Unix and Plan 9 rc both have ('% ' ' ') as the
> default value of $prompt. At least that's how it's described in the
> manual. None of the v8/9/10 tarballs in the archive contain rc code,
> but some contain manual source, and those describe % prompts.
>
> I've seen other references to ; (presumably ('; ' ' ')) as the rc
> prompt but I've never seen it in the wild. Does anyone here know what
> the story is?
>
> khm
>
>
>
>
> From: arnold at skeeve.com
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 09:50:21 CEST
> To: khm at sciops.net, brian at zick.io
> Cc: tuhs at minnie.tuhs.org
>
>
> Kurt H Maier <khm at sciops.net> wrote:
>
>> On Mon, Aug 06, 2018 at 09:53:33PM +0100, Brian Zick wrote:
>>>
>>> rc uses ;
>>
>> Does it? 10th edition Unix and Plan 9 rc both have ('% ' ' ') as the
>> default value of $prompt. At least that's how it's described in the
>> manual. None of the v8/9/10 tarballs in the archive contain rc code,
>> but some contain manual source, and those describe % prompts.
>>
>> I've seen other references to ; (presumably ('; ' ' ')) as the rc
>> prompt but I've never seen it in the wild. Does anyone here know what
>> the story is?
>>
>> khm
>
> I believe that Tom Duff's rc does indeed use ('% ' ' '). But I think that
> Byron Rakitsis's version changed the default to ('; ' ' ') exactly for
> the reason that it's copyable/pastable.
>
> HTH,
>
> Arnold
>
>
>
>
> From: Bakul Shah <bakul at bitblocks.com>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 09:57:11 CEST
> To: Kurt H Maier <khm at sciops.net>
> Cc: Brian Zick <brian at zick.io>, tuhs at minnie.tuhs.org
>
>
> On Tue, 07 Aug 2018 00:31:36 -0700 Kurt H Maier <khm at sciops.net> wrote:
>> On Mon, Aug 06, 2018 at 09:53:33PM +0100, Brian Zick wrote:
>>>
>>> rc uses ;
>>
>> Does it? 10th edition Unix and Plan 9 rc both have ('% ' ' ') as the
>> default value of $prompt. At least that's how it's described in the
>> manual. None of the v8/9/10 tarballs in the archive contain rc code,
>> but some contain manual source, and those describe % prompts.
>>
>> I've seen other references to ; (presumably ('; ' ' ')) as the rc
>> prompt but I've never seen it in the wild. Does anyone here know what
>> the story is?
>
> The es shell (by Haar and Rakitzis) used ; - the reason (as
> per the man page)is that a user can cut-n-paste a previous
> line to rexecute it (for the same reason people use term% and
> cpu% functions to execute their args). Es syntax was derived
> from rc, which may be why the confusion.
>
>
>
>
> From: Michael Kjörling <michael at kjorling.se>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 10:02:56 CEST
> To: tuhs at minnie.tuhs.org
>
>
> On 7 Aug 2018 06:54 +0000, from michael at kjorling.se (Michael Kjörling):
>> the shell will do The Right Thing (tm)
>
> I suspect I must stand corrected on this. Turns out that at least GNU
> bash 4.4.12(1) seems to not like a `;` at the beginning of the command
> line.
>
> $ /bin/bash --version | head -n1
> GNU bash, version 4.4.12(1)-release (x86_64-pc-linux-gnu)
> $ /bin/bash
> $ ; true
> bash: syntax error near unexpected token `;'
> $ echo $?
> 2
> $
>
> Hopefully other shells are more sane.
>
> --
> Michael Kjörling • https://michael.kjorling.se • michael at kjorling.se
> “The most dangerous thought that you can have as a creative person
> is to think you know what you’re doing.” (Bret Victor)
>
>
>
>
> From: Dave Horsfall <dave at horsfall.org>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 10:23:37 CEST
> To: The Eunuchs Hysterical Society <tuhs at tuhs.org>
>
>
> On Tue, 7 Aug 2018, Michael Kjörling wrote:
>
>> Hopefully other shells are more sane.
>
> The MacBook here runs GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin16) and is equally busted, as is plain "sh" on both the Mac and FreeBSD (I can't be bothered checking the Penguin); I use ZSH on FreeBSD and it does The Right Thing (tm), as does ZSH on the Mac.
>
> -- Dave
>
>
> From: KatolaZ <katolaz at freaknet.org>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 10:37:23 CEST
> To: tuhs at minnie.tuhs.org
>
>
> On Tue, Aug 07, 2018 at 06:23:37PM +1000, Dave Horsfall wrote:
>> On Tue, 7 Aug 2018, Michael Kjörling wrote:
>>
>>> Hopefully other shells are more sane.
>>
>> The MacBook here runs GNU bash, version 3.2.57(1)-release
>> (x86_64-apple-darwin16) and is equally busted, as is plain "sh" on both the
>> Mac and FreeBSD (I can't be bothered checking the Penguin); I use ZSH on
>> FreeBSD and it does The Right Thing (tm), as does ZSH on the Mac.
>>
>> -- Dave
>
> I have tried all the shells I have on my linux box. It turns out that
> only ksh and zsh like a ";" at the beginning of the line. Otherwise,
> bash, busybox, ash/dash, mksk, posh, and yash can't bear it.
>
> I really don't see the point of using ";", especially if you need to
> make it clear if a command needs to be run by root.
>
> $ ;-P
> sh: 1: Syntax error: ";" unexpected
>
>
> --
> [ ~.,_ Enzo Nicosia aka KatolaZ - Devuan -- Freaknet Medialab ]
> [ "+. katolaz [at] freaknet.org --- katolaz [at] yahoo.it ]
> [ @) http://kalos.mine.nu --- Devuan GNU + Linux User ]
> [ @@) http://maths.qmul.ac.uk/~vnicosia -- GPG: 0B5F062F ]
> [ (@@@) Twitter: @KatolaZ - skype: katolaz -- github: KatolaZ ]
>
>
>
> From: "Steve Johnson" <scj at yaccman.com>
> Subject: Re: [TUHS] TUHS Digest, Vol 33, Issue 5
> Date: 6 August 2018 at 23:19:31 CEST
> To: "Hellwig Geisse" <hellwig.geisse at mni.thm.de>, tuhs at minnie.tuhs.org
>
>
> I take a somewhat more relaxed view of what a spec should be:
> It should describe a program with enough completeness that a competent
> programmer could write it from the spec alone.
> Each section of the spec should be capable of being tested.
> If all the tests for all the sections pass, then the program is ready
> for general use.
>
> The formal systems I have seen would roll over and die when presented with
> even a simple compiler. Additionally, being able to specify that a particular
> function be carried out by a heapsort, for example, would require that the
> formalism could describe the heapsort and prove it correct. These don't
> grow on trees...
>
> Steve
>
>
>
> ----- Original Message -----
> From: "Hellwig Geisse" <hellwig.geisse at mni.thm.de>
> To:<tuhs at minnie.tuhs.org>
> Cc:
> Sent:Mon, 06 Aug 2018 18:30:30 +0200
> Subject:Re: [TUHS] TUHS Digest, Vol 33, Issue 5
>
>
> On Mo, 2018-08-06 at 08:52 -0700, Bakul Shah wrote:
> >
> > What counts as a "formal spec"? Is it like Justice Potter Stewart's
> > "I know it when I see it" definition or something better?
> >
>
> For me, a "formal spec" should serve two goals:
> 1) You can reason about the thing that is specified.
> 2) The spec can be "executed" (i.e., there is an
> interpreting mechanism, which lets the spec behave
> like the real thing).
>
> Hellwig
>
>
>
> From: Tony Finch <dot at dotat.at>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 12:45:37 CEST
> To: Michael Kjörling <michael at kjorling.se>
> Cc: tuhs at minnie.tuhs.org
>
>
> Michael Kjörling <michael at kjorling.se> wrote:
>>
>> I suspect I must stand corrected on this. Turns out that at least GNU
>> bash 4.4.12(1) seems to not like a `;` at the beginning of the command
>> line.
>
> This is a consequence of the POSIX shell grammar, which doesn't allow
> empty commands.
>
> http://pubs.opengroup.org/onlinepubs/9699919799.2013edition/utilities/V3_chap02.html#tag_18_10
>
> The prompt I have used since about 1997 (and I can't remember where I got
> it from - somewhere on Usenet, probably) in its most distilled form is
>
> :;
>
> although in practice I have a load of extra fluff for username, hostname,
> CWD, etc. usw.
>
> Tony.
> --
> f.anthony.n.finch <dot at dotat.at> http://dotat.at/
> Fair Isle, Faeroes: South or southwest 4 or 5, occasionally 6 for a time.
> Slight or moderate, occasionally rough for a time. Showers. Moderate or good.
>
>
>
> From: Pete Turnbull <pete at dunnington.plus.com>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 13:24:20 CEST
> To: tuhs at minnie.tuhs.org
>
>
> On 07/08/2018 09:02, Michael Kjörling wrote:
>> On 7 Aug 2018 06:54 +0000, from michael at kjorling.se (Michael Kjörling):
>>> the shell will do The Right Thing (tm)
>> I suspect I must stand corrected on this. Turns out that at least GNU
>> bash 4.4.12(1) seems to not like a `;` at the beginning of the command
>> line.
>> $ /bin/bash --version | head -n1
>> GNU bash, version 4.4.12(1)-release (x86_64-pc-linux-gnu)
>> $ /bin/bash
>> $ ; true
>> bash: syntax error near unexpected token `;'
>> $ echo $?
>> 2
>> $
>> Hopefully other shells are more sane.
>
> ksh and sh on an IRIX system don't like it either:
>
> $ ;
> ksh: syntax error: `;' unexpected
> $
>
> csh and tcsh don't mind.
>
> Of course it works in rc itself, which is the point, really, and I wonder how often anyone pasted from one shell into another. All the rc use I've seen did indeed use "; " as the prompt, but that was all at the University of York, starting in 1993.
>
> --
> Pete
> Pete Turnbull
>
>
>
>
> From: Doug McIlroy <doug at cs.dartmouth.edu>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 14:34:16 CEST
> To: tuhs at tuhs.org
>
>
>> The Bourne shell (V7) had setable PS1 (start of command) and PS2 (continuation prompts)
>
> When PS2 came on the scene, Bob Morris noticed that it most often appeared
> because of a missing close quote. Therefore he set PS2="hit interrupt".
>
>
>
>
> From: Brian Zick <brian at zick.io>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 17:15:07 CEST
> To: Kurt H Maier <khm at sciops.net>
> Cc: tuhs at minnie.tuhs.org
>
>
>>> rc uses ;
>>
>> Does it? 10th edition Unix and Plan 9 rc both have ('% ' ' ') as the
>> default value of $prompt. At least that's how it's described in the
>> manual.
>
> In NetBSD 7 the default is ';', but I don't see any reference to a default $prompt in the manual on that system. I wonder if this was a change unique to Berkeley.
>
> B
>
>
>
>
> From: "John P. Linderman" <jpl.jpl at gmail.com>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 17:52:57 CEST
> To: Brian Zick <brian at zick.io>
> Cc: Kurt H Maier <khm at sciops.net>, tuhs at minnie.tuhs.org
>
>
> On vacation, with just an iPad keyboard, so I apologize for not doing more digging. As I noted, when taking the blame for the Great Echo Schism, my early exposure to a hp2640 terminal that allowed “rentry” of a previous command was partly to blame. It also led me to use a PS1 ending in @, the default line-kill. When I reentered a command, the @ wiped out the prompt stuff, and only the command survived.
>
> On Tue, Aug 7, 2018 at 10:15 AM Brian Zick <brian at zick.io <mailto:brian at zick.io>> wrote:
> > > rc uses ;
> >
> > Does it? 10th edition Unix and Plan 9 rc both have ('% ' ' ') as the
> > default value of $prompt. At least that's how it's described in the
> > manual.
>
> In NetBSD 7 the default is ';', but I don't see any reference to a default $prompt in the manual on that system. I wonder if this was a change unique to Berkeley.
>
> B
>
>
>
> From: Lyndon Nerenberg <lyndon at orthanc.ca>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 19:35:49 CEST
> To: Tony Finch <dot at dotat.at>
> Cc: Michael Kjörling <michael at kjorling.se>, tuhs at minnie.tuhs.org
>
>
>> The prompt I have used since about 1997 (and I can't remember where I got
>> it from - somewhere on Usenet, probably) in its most distilled form is
>>
>> :;
>
> I forget where I stole this from. It lives in $home/lib/profile on my Plan9 machines:
>
> # /n/sources/contrib/lyndon/prompt.rc
> fn : {}
> fn setprompt {
> prompt = (': '^`{cat /dev/user}^@^`{cat /dev/sysname}^':'^`{pwd}^'; ' ' ')
> }
> fn cd { builtin cd $* && setprompt }
> setprompt
>
>
>
>
>
> From: Cág <ca6c at bitmessage.ch>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 20:09:51 CEST
> To: tuhs at minnie.tuhs.org
>
>
> Brian Zick wrote:
>
>> In NetBSD 7 the default is ';', but I don't see any reference to a
>> default $prompt in the manual on that system.
>
> It's not. '$' is default for sh and ksh, and '%' for csh. I think
> it maybe has never been ';'.
>
> --
> caóc
>
>
>
>
>
> From: arnold at skeeve.com
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 20:51:52 CEST
> To: tuhs at minnie.tuhs.org, ca6c at bitmessage.ch
>
>
> C??g <ca6c at bitmessage.ch> wrote:
>
>> Brian Zick wrote:
>>
>>> In NetBSD 7 the default is ';', but I don't see any reference to a
>>> default $prompt in the manual on that system.
>>
>> It's not. '$' is default for sh and ksh, and '%' for csh. I think
>> it maybe has never been ';'.
>>
>> --
>> ca??c
>>
>
> Brian was referring to rc(1) in NetBSD. I suspect it's Byron's rc
> and I think the default there is ';'.
>
> Arnold
>
>
>
>
> From: Cág <ca6c at bitmessage.ch>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 21:00:22 CEST
> To: tuhs at minnie.tuhs.org
>
>
> arnold wrote:
>
>> Brian was referring to rc(1) in NetBSD. I suspect it's Byron's rc
>> and I think the default there is ';'.
>
> rc is not shipped with NetBSD. There's Byron's rc in pkgsrc, so it could
> be that.
>
> --
> caóc
>
>
>
>
>
> From: Brian Zick <brian at zick.io>
> Subject: Re: [TUHS] Origins of shell prompt suffixes % $ > #
> Date: 7 August 2018 at 21:06:03 CEST
> To: tuhs at minnie.tuhs.org
>
>
> On Tue, Aug 7, 2018, at 8:00 PM, Cág wrote:
>> arnold wrote:
>>
>>> Brian was referring to rc(1) in NetBSD. I suspect it's Byron's rc
>>> and I think the default there is ';'.
>>
>> rc is not shipped with NetBSD. There's Byron's rc in pkgsrc, so it could
>> be that.
>
> Yes, I was referring to the rc in pkgsrc.
>
> B
>
>
>
>
>
> _______________________________________________
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