Linux-Dash Archive mirror
 help / color / mirror / Atom feed

From: Alex Waite <alexqw85@gmail.com>
To: dash@vger.kernel.org
Subject: Pattern matching faster than math
Date: Wed, 25 Mar 2015 14:51:56 +0100	[thread overview]
Message-ID: <meuehs$n4e$1@ger.gmane.org> (raw)

Hello,

This isn't a problem per-se, but I'm curious if anyone can shed some 
light on why this is so.

I have a script where I'm checking if the contents of a variable is an 
integer. An easy/hacky way to do this is

[ "$var" -ge 0 2> /dev/null ] || echo "is not int"

But this caused posh to segfault, so I went for a pattern matching 
solution instead:

[ -z "${var##*[!0-9]*}" ] && echo "is not int"

This works well, and it makes posh happy. But what's surprising to me is 
that it's faster.

I have more of a write-up in a commit message: 
https://github.com/zfsnap/zfsnap/commit/ed6326f0006ed18b7d8bb79d5ee8f06142847f41

Any thoughts or insight? Am I making some faulty assumption here?

Thanks for your time.

---Alex

                 reply	other threads:[~2015-03-25 13:52 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

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='meuehs$n4e$1@ger.gmane.org' \
    --to=alexqw85@gmail.com \
    --cc=dash@vger.kernel.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

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 read-only IMAP folder(s) and NNTP newsgroup(s).