From: Nadav Har'El <nyh@math.technion.ac.il>
To: sergio <mailbox@sergio.spb.ru>
Cc: zsh-users@zsh.org
Subject: Re: [[ and [
Date: Wed, 7 Mar 2012 10:12:11 +0200 [thread overview]
Message-ID: <20120307081211.GB15125@fermat.math.technion.ac.il> (raw)
In-Reply-To: <4F55EF85.3050809@sergio.spb.ru>
On Tue, Mar 06, 2012, sergio wrote about "Re: [[ and [":
> On 03/06/2012 10:05 AM, Bart Schaefer wrote:
>
> What was the reason to implement [[ ]]? What advantages it gives? As
> I see [[ ]] and [ ] provides same features.
In the original Unix, "[" was not a shell builtin - it was a normal
program, /bin/[, normally a hard link to /bin/test. As such, you needed
to follow ordinary (and annoying) quoting rules for its parameters.
When ksh (and later zsh and bash) implemented '[' as a builtin, it
retained its exact old behavior for backward compatibility, this should NOT
and instead invented a new syntax, the [[, for an improved version, with
less need for quoting and new tests, including for example the "<" operator
for text dictionary-order (on why this deals with text and not numbers,
see my separate reply).
--
Nadav Har'El | Wednesday, Mar 7 2012,
nyh@math.technion.ac.il |-----------------------------------------
Phone +972-523-790466, ICQ 13349191 |Linux: Because a PC is a terrible thing
http://nadav.harel.org.il |to waste.
next prev parent reply other threads:[~2012-03-07 8:22 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-04 2:36 sergio
2012-03-04 4:24 ` Bart Schaefer
2012-03-06 0:32 ` sergio
2012-03-06 6:05 ` Bart Schaefer
2012-03-06 11:05 ` sergio
2012-03-06 11:35 ` Peter Stephenson
2012-03-06 11:44 ` Peter Stephenson
2012-03-06 11:53 ` Mikael Magnusson
2012-03-07 9:02 ` Nadav Har'El
2012-03-07 9:05 ` Mikael Magnusson
2012-03-07 9:21 ` Nadav Har'El
2012-03-07 15:27 ` Bart Schaefer
2012-03-07 8:52 ` Nadav Har'El
2012-03-07 9:43 ` Peter Stephenson
2012-03-07 14:11 ` Nadav Har'El
2012-03-07 14:27 ` Peter Stephenson
2012-03-07 18:38 ` Mark
2012-03-06 16:16 ` sergio
2012-03-06 16:29 ` Peter Stephenson
2012-03-06 17:40 ` sergio
2012-03-07 8:12 ` Nadav Har'El [this message]
2012-03-04 4:50 ` Kurtis Rader
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120307081211.GB15125@fermat.math.technion.ac.il \
--to=nyh@math.technion.ac.il \
--cc=mailbox@sergio.spb.ru \
--cc=zsh-users@zsh.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/zsh/
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).