Path: csiph.com!xmission!news.snarked.org!news.linkpendium.com!news.linkpendium.com!panix!usenet.stanford.edu!not-for-mail
From: L A Walsh <bash@tlinx.org>
Newsgroups: gnu.bash.bug
Subject: Re: Not missing, but very hard to see (was Re: Backslash missing in brace expansion)
Date: Thu, 12 Dec 2019 18:57:53 -0800
Lines: 49
Approved: bug-bash@gnu.org
Message-ID: <mailman.766.1576205886.1979.bug-bash@gnu.org>
References: <20191205201157.cd481936f76d95bbdfabc73c@schrader-schulte.de> <662e2328-f331-c554-afcf-fd3819f6beab@case.edu> <20191206055304.076d6115afa3a4f2a6a21c34@schrader-schulte.de> <5b5064a8-7175-42e7-1eb5-6374dee6c11e@redhat.com> <21761e28-c496-ff67-d7b7-628c9325085f@iki.fi> <9dd3a388-39b1-c059-de99-813f1e411764@case.edu> <5DF2987E.5000309@tlinx.org> <568aeaaa-22b3-c7b9-0e18-a92bef6d2ffb@iki.fi> <5DF2FE31.9070406@tlinx.org>
NNTP-Posting-Host: lists.gnu.org
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Trace: usenet.stanford.edu 1576205886 12672 209.51.188.17 (13 Dec 2019 02:58:06 GMT)
X-Complaints-To: action@cs.stanford.edu
To: bug-bash <bug-bash@gnu.org>
Envelope-to: bug-bash@gnu.org
User-Agent: Thunderbird
In-Reply-To: <568aeaaa-22b3-c7b9-0e18-a92bef6d2ffb@iki.fi>
X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x (no timestamps) [generic] [fuzzy]
X-Received-From: 173.164.175.65
X-BeenThere: bug-bash@gnu.org
X-Mailman-Version: 2.1.23
Precedence: list
List-Id: Bug reports for the GNU Bourne Again SHell <bug-bash.gnu.org>
List-Unsubscribe: <https://lists.gnu.org/mailman/options/bug-bash>, <mailto:bug-bash-request@gnu.org?subject=unsubscribe>
List-Archive: <https://lists.gnu.org/archive/html/bug-bash>
List-Post: <mailto:bug-bash@gnu.org>
List-Help: <mailto:bug-bash-request@gnu.org?subject=help>
List-Subscribe: <https://lists.gnu.org/mailman/listinfo/bug-bash>, <mailto:bug-bash-request@gnu.org?subject=subscribe>
X-Mailman-Original-Message-ID: <5DF2FE31.9070406@tlinx.org>
X-Mailman-Original-References: <20191205201157.cd481936f76d95bbdfabc73c@schrader-schulte.de> <662e2328-f331-c554-afcf-fd3819f6beab@case.edu> <20191206055304.076d6115afa3a4f2a6a21c34@schrader-schulte.de> <5b5064a8-7175-42e7-1eb5-6374dee6c11e@redhat.com> <21761e28-c496-ff67-d7b7-628c9325085f@iki.fi> <9dd3a388-39b1-c059-de99-813f1e411764@case.edu> <5DF2987E.5000309@tlinx.org> <568aeaaa-22b3-c7b9-0e18-a92bef6d2ffb@iki.fi>
Xref: csiph.com gnu.bash.bug:15724



On 2019/12/12 13:01, Ilkka Virta wrote:
> On 12.12. 21:43, L A Walsh wrote:
>   
>> On 2019/12/06 14:14, Chet Ramey wrote:
>>
>> Seems very hard to print out that backquote though.  Closest I got
>> was bash converting it to "''":
>>     
>
> The backquote is in [6], and the backslash disappears, you just get the 
> pair of quotes in [2] because that's how printf %q outputs an empty string.
>   
-----

    I'm sorry, but you are mistaken.

    The characters from 'Z' (0x5A) through 'z' (0x61) are:

0x5A 0x5B 0x5C 0x5D 0x5E 0x5F 0x60 0x61
 Z    [    \    ]     ^   _     `    a

the backslash comes between the two square brackets.

Position [6] is the "Grave Accent" (or backquote).

It is quoted properly.

As for %q printing an empty string for 0x5C

         "%q" causes  printf to output the corresponding argument in a
         format that can be reused as shell input.

    For that string to be empty would mean there is no character at hex
value 0x5C (unicode U+005C), which isn't so.

>   
>>>  read -r -a a< <(printf "%q " {Z..a})
>>>  my -p a
>>>       
>> declare -a a=([0]="Z" [1]="\\[" [2]="''" [3]="\\]" [4]="\\^" [5]="_" 
>> [6]="\\\`" [7]="a")
>>     
>
>
>