[Novalug] need grep help

James Ewing Cottrell 3rd JECottrell3@Comcast.NET
Fri Mar 16 17:23:01 EDT 2012


On 3/16/2012 3:36 PM, John Holland wrote:
> Does \t escape all kinds of whitespace? don't you need some sort of * 
> operator after the [\t] ?
Yes, I forgot the *. Kudos.

No, \t is Tab Only. There was also a space before it. Newlines take care 
of themselves. Nobody uses \v, and \f is often treated as a newline by 
everything but printers.

JIM
>
>
> On 3/16/12 4:12 PM, James Ewing Cottrell 3rd wrote:
>> Cleverness Kudos for combining the two RE's into one, but Performance 
>> Dings for not keeping them separare.
>>
>> For all comments, the ".*" part will have to be scanned unnecessarily.
>>
>> I still say that '^$|[ \t]#' is better, and more clear.
>>
>> Besides...what happens when you want to add other types of comments? 
>> Bind files use ';'. C++ and others use '//'.
>>
>> JIM
>>
>> P.S. I won't even mention the [[:space:]] abomination.
>>
>> On 3/16/2012 11:22 AM, Kevin Cole wrote:
>>> On Thu, Mar 15, 2012 at 20:00, Kevin Cole <dc.loco@gmail.com 
>>> <mailto:dc.loco@gmail.com>> wrote:
>>>
>>>
>>>         Been there, done that.  So often in fact that I add this
>>>         alias to my .bash_aliases wherever I go:
>>>
>>>         alias decomment='egrep -v "^[[:space:]]*(#.*)?$" '
>>>
>>>
>>>     P.S. The pseudo-English translation of that is (sort of) "search
>>>     for lines that do not begin with zero or more spaces followed by
>>>     at least one occurance of zero or more hash marks, with nothing
>>>     else until the end of the line".
>>>
>>>
>>> Correction: The code is good. The psuedo-English is bad: It should 
>>> read something like "search for lines that do not match  zero or 
>>> more spaces at the begining of a line, followed by zero or one 
>>> occurances of (a hash mark followed by any characters), followed by 
>>> the end of the line". Still unreadable in English, but at least more 
>>> accurate.
>>>
>>>
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>>
>>
>>
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