Re: regex lesson (again)

[Danny Sauer <sauer@cloudmaster.com>]

You are correct, sir.  It appears to be cutting out lines that have only
whitespace or whitespace followed by a comment.  [:space:] is the POSIX
regexp class that's equivilent to Perl's \s (one whitespace char). It's
inside of another set of brackets because they're supposed to be used
inside of character classes...

--Danny

On Thu, Apr 19, 2001 at 09:22:26PM -0500, charles@lunarmedia.net wrote:
> i am reading through the init script for iptables, and i am not certain
> how this regex is doing what its doing:
> 
> grep -v "^[[:space:]]*#"
> 
> or this one
> 
> grep -v '^[[:space:]]*$'
> 
> the grep -v i understand, but what is going on with this
> 
> 	^[[:space:]]*#
> 
> 	^ 		beginning
> 	[ 		grouping
> 	[:space:]	is this some sort of way to indicate
> 			whitespace or something?
> 	]		end of group
> 	* 		any number of this grouping
> 	#		a literal pound
> 
> i am pretty sure that this is just a grep for any line that has some/no
> whitespace and then a literal # character. so, i assume this is grepping
> for lines that do not begin with a comment. i am just curious as to know
> how exactly its working.
> the second regex looks to be grepping for lines that are strictly
> whitespace (or in the case of -v lines that are not strictly whitespace.)
> 
> thanks
-
To unsubscribe, send email to majordomo@luci.org with
"unsubscribe luci-discuss" in the body.