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Re: [DOC] Incomplete explanation about the regex =~ operator


From: Chet Ramey
Subject: Re: [DOC] Incomplete explanation about the regex =~ operator
Date: Wed, 9 Jan 2019 15:37:10 -0500
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:60.0) Gecko/20100101 Thunderbird/60.4.0

On 1/9/19 2:27 PM, kevin wrote:
> My message was poorly formatted (I lack of experience) and consequently you
> misunderstood it.
> The shell operation is unusual when a regular expression appears inside a
> conditional expression. Indeed, neither the Bash man page or the Bash
> Reference Manual indicates that the shell quotes some characters internally
> (Bash FAQ: http://git.savannah.gnu.org/cgit/bash.git/tree/doc/FAQ#n1927).

"Any part of  the  pat-
 tern  may be quoted to force the quoted portion to be matched as
 a string."

> Moreover, the explanation in the Bash FAQ is unclear; it lacks examples to
> know when "an interference" occurred.

What is "an interference"?


> Look at the following answer to get an overview of the issue:
> https://stackoverflow.com/a/12696899

That answer is correct: bash uses the C library's regexp library and
only guarantees that POSIX EREs work.

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/



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