Comments on: Regex Challenge http://ubuntu-tutorials.com/2008/11/17/regex-challenge/ Enhancing your Ubuntu experience! Thu, 02 Feb 2012 10:29:43 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: G N http://ubuntu-tutorials.com/2008/11/17/regex-challenge/#comment-7624 G N Fri, 02 Jan 2009 16:46:40 +0000 http://ubuntu-tutorials.com/?p=918#comment-7624 I second "grep ." as the easiest solution. Perl/Ruby shouldn't be too complicated either: perl -lane 'print if /./' ruby -lane 'p if /./' Too filter whitespace lines (not only blanks): perl -lane 'print if /\S/' ruby -lane 'print if /\S/' I second “grep .” as the easiest solution.

Perl/Ruby shouldn’t be too complicated either:

perl -lane ‘print if /./’
ruby -lane ‘p if /./’

Too filter whitespace lines (not only blanks):

perl -lane ‘print if /\S/’
ruby -lane ‘print if /\S/’

]]> By: Khalil Fazal http://ubuntu-tutorials.com/2008/11/17/regex-challenge/#comment-7389 Khalil Fazal Fri, 05 Dec 2008 02:22:53 +0000 http://ubuntu-tutorials.com/?p=918#comment-7389 emacs22 C-M-% C-q C-j C-q C-j + C-q C-j and it will then ask you "[y/n]?" emacs22

C-M-%

C-q C-j C-q C-j +

C-q C-j

and it will then ask you “[y/n]?”

]]> By: Wolfger http://ubuntu-tutorials.com/2008/11/17/regex-challenge/#comment-6969 Wolfger Thu, 20 Nov 2008 15:35:23 +0000 http://ubuntu-tutorials.com/?p=918#comment-6969 Late to the challenge, but here's the regex I whipped out off the top of my head: s/\n\W*\n/\n/g My perl code slurps the entire file to a variable and regexes that variable, then splits on newline to an array. Late to the challenge, but here’s the regex I whipped out off the top of my head:
s/\n\W*\n/\n/g

My perl code slurps the entire file to a variable and regexes that variable, then splits on newline to an array.

]]> By: Mike http://ubuntu-tutorials.com/2008/11/17/regex-challenge/#comment-6933 Mike Wed, 19 Nov 2008 13:27:24 +0000 http://ubuntu-tutorials.com/?p=918#comment-6933 Hm... why do I have to post this three times? :-/ awk -v RS="[\n ,]+" '{print}' < u.txt Hm… why do I have to post this three times? :-/

awk -v RS=”[\n ,]+” ‘{print}’ < u.txt

]]> By: meyer http://ubuntu-tutorials.com/2008/11/17/regex-challenge/#comment-6909 meyer Tue, 18 Nov 2008 22:05:55 +0000 http://ubuntu-tutorials.com/?p=918#comment-6909 boo that should be foreach \... boo that should be foreach \…

]]> By: meyer http://ubuntu-tutorials.com/2008/11/17/regex-challenge/#comment-6908 meyer Tue, 18 Nov 2008 22:04:46 +0000 http://ubuntu-tutorials.com/?p=918#comment-6908 #!/usr/bin/perl open(FILE,"usernames.txt") || die "Could not open usernames.txt: $!\n"; foreach () {if ($_ =~ /\w+/) {print "$_"}} close(FILE); Of course you'd have to be crazy to use perl for something that easy in grep/awk!! #!/usr/bin/perl
open(FILE,”usernames.txt”) || die “Could not open usernames.txt: $!\n”;
foreach () {if ($_ =~ /\w+/) {print “$_”}}
close(FILE);

Of course you’d have to be crazy to use perl for something that easy in grep/awk!!

]]> By: adam-collard http://ubuntu-tutorials.com/2008/11/17/regex-challenge/#comment-6907 adam-collard Tue, 18 Nov 2008 21:13:06 +0000 http://ubuntu-tutorials.com/?p=918#comment-6907 import sys for line in sys.stdin: usernames = [name.strip() for name in line.split(",")] if not any(usernames): continue for username in usernames: print username Readability - 1 The way of the Pathologically Eclectic Rubbish Lister - 0 import sys

for line in sys.stdin:
usernames = [name.strip() for name in line.split(",")]
if not any(usernames):
continue
for username in usernames:
print username

Readability – 1
The way of the Pathologically Eclectic Rubbish Lister – 0

]]> By: Kai http://ubuntu-tutorials.com/2008/11/17/regex-challenge/#comment-6893 Kai Tue, 18 Nov 2008 15:18:17 +0000 http://ubuntu-tutorials.com/?p=918#comment-6893 Just delete blank lines: perl -pi -e 's/\A\s+\z//' usernames.txt With commas too: perl -pi -e 's/,\s*/\n/g;s/\A\s+\z//' usernames.txt Just delete blank lines:
perl -pi -e ‘s/\A\s+\z//’ usernames.txt
With commas too:
perl -pi -e ‘s/,\s*/\n/g;s/\A\s+\z//’ usernames.txt

]]> By: Jeff Schroeder http://ubuntu-tutorials.com/2008/11/17/regex-challenge/#comment-6889 Jeff Schroeder Tue, 18 Nov 2008 13:53:55 +0000 http://ubuntu-tutorials.com/?p=918#comment-6889 Regex can be avoided in most cases and should be when possible. Try this: awk '/^[a-zA-Z]/{print $1}' usernames.txt Unlike just removing the newlines, that prevents cases where some crazy admin has commented out users or whatnot in /etc/passwd. If that was a standard passwd file you could do something more like: awk -F: '/^[a-zA-Z]/{if ($3 !~ 0) print $1}' /etc/passwd If it is and Ubuntu / Debian server where normal uids start at 1000, you could do this for a listing of usernames: awk -F: '/^[a-zA-Z]/{if ($3 >= 1000 && $1 != "nobody") print $1}' /etc/passwd Usernames must start with a character and can't start with a number from my understanding so that should work fairly well. Regex can be avoided in most cases and should be when possible.

Try this:
awk ‘/^[a-zA-Z]/{print $1}’ usernames.txt

Unlike just removing the newlines, that prevents cases where some crazy admin has commented out users or whatnot in /etc/passwd.

If that was a standard passwd file you could do something more like:
awk -F: ‘/^[a-zA-Z]/{if ($3 !~ 0) print $1}’ /etc/passwd

If it is and Ubuntu / Debian server where normal uids start at 1000, you could do this for a listing of usernames:
awk -F: ‘/^[a-zA-Z]/{if ($3 >= 1000 && $1 != “nobody”) print $1}’ /etc/passwd

Usernames must start with a character and can’t start with a number from my understanding so that should work fairly well.

]]> By: Mark Drago http://ubuntu-tutorials.com/2008/11/17/regex-challenge/#comment-6885 Mark Drago Tue, 18 Nov 2008 12:52:14 +0000 http://ubuntu-tutorials.com/?p=918#comment-6885 Mackenzie: sed -e 's/,/\n/g' -e 's/[ \t]//g' -e '/^$/d' usernames.txt Converts commas to newlines, strips whitespace, then removes blanks. Mark. Mackenzie:
sed -e ‘s/,/\n/g’ -e ‘s/[ \t]//g’ -e ‘/^$/d’ usernames.txt

Converts commas to newlines, strips whitespace, then removes blanks.

Mark.

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