Date: Mon, 28 Sep 2015 14:07:52 +0100 From: RW <rwmaillists@googlemail.com> To: freebsd-questions@freebsd.org Subject: Re: 10.2-RELEASE/amd64: grep regex syntax vs. grep-bug Message-ID: <20150928140752.0c182f1e@gumby.homeunix.com> In-Reply-To: <00e801d0f9e2$125ec430$371c4c90$@mgedv.net> References: <00e801d0f9e2$125ec430$371c4c90$@mgedv.net>
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On Mon, 28 Sep 2015 13:37:35 +0200 no@spam@mgEDV.net wrote: > hi folks, > the goal: grep, that a variable contains a number and JUST digits. > # setup sample variable - we're on /bin/sh @ 10.2-RELEASE/amd64. > x="" > # od output the content of the variable to ensure content > echo "$x" | od -ctdC > 0000000 \n > 10 > 0000001 > # now try /usr/bin/grep'pin (C locale) that it contains... > # ^ at BOL... > # [0-9] require a digit > # * ... and digits following You're confusing + and *. [0-9]* matches any number of digits including zero [0-9]+ matches one or more digits. > # $ ...until we reach EOL > # ... but...: > echo "$x" | grep -c '^[0-9]*$' > 1 <== WHY?
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