From: Bakul Shah <bakul@iitbombay.org>
To: Jon Steinhart <jon@fourwinds.com>
Cc: TUHS main list <tuhs@minnie.tuhs.org>
Subject: Re: [TUHS] Systematic approach to command-line interfaces [ meta issues ]
Date: Sat, 31 Jul 2021 15:20:15 -0700 [thread overview]
Message-ID: <BAE12EE8-8D98-473F-A2BA-25494ED7A0DE@iitbombay.org> (raw)
In-Reply-To: <202107312216.16VMGwTX2446561@fourwinds.com>
-- Bakul
> On Jul 31, 2021, at 3:16 PM, Jon Steinhart <jon@fourwinds.com> wrote:
>
> Bakul Shah writes:
>> On Jul 31, 2021, at 12:20 PM, Jon Steinhart <jon@fourwinds.com> wrote:
>>>
>>> So I never got getopt(). One of my rules is that I don't use a library
>>> in cases where the number of lines of gunk that that it takes to use a
>>> library function is >= the number of lines to just write it myself. Yeah,
>>> I know the "but the library has more eyeballs and is debugged" argument
>>> but in reality libraries are the source of many bugs. I've always taken
>>> the approach that I would never hire someone who had to use a library to
>>> implement a singly-linked list.
>>
>> getopt() is perhaps the wrong solution but consider something like MH,
>> whose commands all follow a common pattern. Consider:
>>
>> - options (switches) all start with a single '-'
>> - they may be abbreviated to a unique prefix.
>> - Boolean options may be inverted by prepending -no (e.g. -nolist)
>> - value options may also have -no format to remove a previous (or default) value
>> - options may appear anywhere and the last instance wins
>>
>> But different commands take different options. It would make sense to factor
>> out common parsing, help etc. for a consistent treatment. In my Go code for
>> parsing MH like options I used Go's flag package as a model.
>>
>> Personally I vastly prefer MH style option processing to either single char
>> options or --very-long-names which can't be abbreviated. Never mind options for
>> commands like gcc, who can even remember 40+ ls options?
>>
>> But I haven't thought about how to extend this for shell scripts, or
>> exposing these so that shells like zsh can do command completion. To specify
>> these you need a vector of tuples (name, type, default, brief-help) but that
>> is painful to do in a shell.
>
> Ah, well, you've given away the secret of real UNIX geezers, we're on both
> this mailing list and the nmh list :-)
:-)
> Yes, I'm mostly happy with the way that nmh does options.
>
> I guess that I would look more kindly on getopt if it had existed much earlier
> so that people writing new commands would be encouraged to use the same format.
> Not as happy with it as an afterthought.
>
> Once again, I have to go back to the meatspace locality of reference issues.
> Sure, it would be nice to be able to factor out common parsing, for example
> if a related set of programs shared the same option set. But unless it's
> something huge, I'd just put it in it's own file and use it for multiple
> programs; I wouldn't put it in a library. My point is that the code that
> does the actual parsing is really trivial, and not necessarily the best
> use of a library.
>
> As far as help goes, I don't expect help built into command line programs;
> I expect to look up error messages on the manual pages. I'm happy with a
> generic usage error as most "helpful" output that I get from programs is
> not actually helpful.
Note that -help in MH program is far more useful as it spells out the full option name.
Consider
% refile -he
Usage: refile [msgs] [switches] +folder ...
switches are:
-draft
-[no]link
-[no]preserve
-[no]retainsequences
-[no]unlink
-src +folder
-file file
-rmmproc program
-normmproc
-version
-help
...
vs
% ls -z
ls: invalid option -- z
usage: ls [-ABCFGHILPRSTUWZabcdfghiklmnopqrstuwxy1,] [--color=when] [-D format] [file ...]
next prev parent reply other threads:[~2021-07-31 22:21 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-31 12:25 [TUHS] Systematic approach to command-line interfaces Michael Siegel
2021-07-31 13:05 ` Dan Halbert
2021-07-31 14:21 ` Adam Thornton
2021-07-31 14:25 ` Adam Thornton
2021-07-31 15:45 ` Richard Salz
2021-07-31 16:03 ` Clem Cole
2021-07-31 16:06 ` Richard Salz
2021-07-31 16:21 ` Clem Cole
2021-07-31 16:17 ` Clem Cole
2021-07-31 16:30 ` Dan Cross
2021-07-31 15:56 ` Paul Winalski
2021-07-31 16:19 ` Dan Cross
2021-08-01 17:44 ` Chet Ramey
2021-08-01 21:53 ` Dan Cross
2021-08-01 23:21 ` Chet Ramey
2021-08-01 23:36 ` John Cowan
2021-08-01 23:49 ` Larry McVoy
2021-08-02 0:28 ` Larry McVoy
2021-08-01 23:58 ` Dan Cross
2021-08-02 0:29 ` Steve Nickolas
2021-08-02 0:13 ` Andrew Warkentin
2021-08-02 0:18 ` John Cowan
2021-08-02 0:54 ` Andrew Warkentin
2021-08-02 1:04 ` Dan Cross
2021-08-02 1:05 ` Theodore Ts'o
2021-08-02 2:10 ` Andrew Warkentin
2021-08-02 2:32 ` Bakul Shah
2021-08-02 17:33 ` Lars Brinkhoff
2021-09-28 17:46 ` Greg A. Woods
2021-09-28 18:10 ` Larry McVoy
2021-09-29 16:40 ` Greg A. Woods
2021-09-29 16:57 ` Larry McVoy
2021-09-30 17:31 ` Greg A. Woods
2021-09-29 23:10 ` Phil Budne
2021-08-02 17:37 ` Lars Brinkhoff
2021-08-02 18:52 ` Clem Cole
2021-08-02 20:59 ` John Cowan
2021-08-02 21:06 ` Al Kossow
2021-08-02 21:14 ` Clem Cole
2021-08-02 21:13 ` Clem Cole
2021-08-01 16:51 ` Michael Siegel
2021-08-01 17:31 ` Jon Steinhart
2021-07-31 16:41 ` Clem Cole
2021-07-31 17:41 ` John Cowan
2021-07-31 17:30 ` Anthony Martin
2021-07-31 17:46 ` John Cowan
2021-07-31 18:56 ` Michael Siegel
2021-07-31 19:41 ` Clem Cole
2021-07-31 21:30 ` Michael Siegel
2021-08-01 17:48 ` Chet Ramey
2021-08-01 19:23 ` Richard Salz
2021-08-01 23:26 ` Chet Ramey
2021-07-31 19:20 ` [TUHS] Systematic approach to command-line interfaces [ meta issues ] Jon Steinhart
2021-07-31 21:06 ` Richard Salz
2021-07-31 21:32 ` Jon Steinhart
2021-07-31 21:37 ` Richard Salz
2021-07-31 21:55 ` Jon Steinhart
2021-07-31 22:10 ` Warner Losh
2021-07-31 22:19 ` Larry McVoy
2021-07-31 22:20 ` Jon Steinhart
2021-07-31 23:26 ` Warner Losh
2021-07-31 23:41 ` Jon Steinhart
2021-07-31 22:04 ` Bakul Shah
2021-07-31 22:13 ` Larry McVoy
2021-07-31 22:14 ` Bakul Shah
2021-07-31 22:17 ` Bakul Shah
2021-07-31 22:16 ` Jon Steinhart
2021-07-31 22:20 ` Bakul Shah [this message]
2021-08-01 18:17 Douglas McIlroy
2021-08-01 19:48 ` arnold
2021-08-01 21:30 ` John Cowan
2021-08-02 12:11 ` Steffen Nurpmeso
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