Re: Yahoo! Groups: Welcome to sed-users. Visit today!

--- In [email protected], Joe Gain <joe.gain@...> wrote:
>
> Hi Luigi,
> 
> you need to take the time to look at how regular expressions are
> built. When you are only copying an pasting it's very frustrating,
> because you can't understand why something happens.
> 
> The first chapter in the regular expressions book from O'Reilly is a
> really good start.


here are some links to aid you in your learning (first is best,in my opinion)

sed --general--

http://linuxtopia.org/online_books/linux_tool_guides/the_sed_faq/index.html

http://pubs.opengroup.org/onlinepubs/007904875/utilities/sed.html

--regex stuff--

http://tldp.org/LDP/abs/html/regexp.html

http://www.regular-expressions.info/tutorial.html

--------------------------

the linuxtopia(1st link) I found to be really helpfull, and easy to understand.

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> 
> On Wed, Apr 25, 2012 at 8:06 PM, Luigi Assom <luigi.assom@...> wrote:
> > Joe, Cameron, thank you for your help!
> >
> > I did not know sed and tr command, they are totally new and the syntax
> > really complex, and i don't know perl as well. I did not understand what
> > you mean exactly, but I tried to copy the sytax you sent, barely as it is..
> > the only thing which worked a bit seems to be this:
> > sed -n -e 's/\(<a[^h]*href="\)\([^"]*\)"\([^>]*>\)/\2/g; p'
> >
> > so I was able to place the url inside the <a> tag outside which is good :)
> > I could not split end of lines, because it is long text with no "\n"
> > characters.
> 
> That's good if you have no newline characters. Sed is a _s_treem _ed_itor!
> 
> That's right, I would try and remove the surrounding tag (and
> attributes) from the text that you want which is inside a tag. And
> then remove all the other tags.
> 
> Perl is good because it gives you more control over your data. You can
> also learn some basic perl pretty quickly.
> 
> >
> > I just need to strip out all the other html tags (I don't need them) and
> > keep only plain text outside the tags.
> >
> > so I will have a file like
> > url texttext text text text text url text text text text text
> > and then I should be ok to handle it.
> >
> > Maybe is there any GUI interface to use sed on mac?
> > thank you for your help!
> 
> I don't know of any, maybe there is something online- a web
> application, but I don't know.
> >
> > Luigi
> >
> > On Wed, Apr 25, 2012 at 12:14 AM, Cameron Simpson <cs@...> wrote:
> >
> >> Joe has the truth here. I'm just adding a few remarks.
> >>
> >> On 24Apr2012 13:05, Joe Gain <joe.gain@...> wrote:
> >> | one of sed's problems is dealing with newline characters
> >>
> >> Remark: specificly because it deals with a line at a time.
> >>
> >> | and you have
> >> | your html anchor tags split over new lines. There's probably a smart
> >> | way to overcome this using sed (and sed's line buffer), but it's not
> >> | an easy alternative.
> >> |
> >> | I think the best way for you is to:
> >> |
> >> | 1. remove all the new line characters,or at least don't split tags
> >> | with new lines (there are many ways to do this, depending on which
> >> | version of sed you are using, could be as easy as # sed -n -e
> >> | 's/\n//g; p' data.html)
> >>
> >> Or, not using sed:
> >>
> >>  ( tr -d '\012' < data.html ; echo ) | sed other-sed-work-now....
> >>
> >> This removes all the newlines using tr, then adds one at the end with
> >> echo, thus putting all the text on a single line.
> >>
> >> personally I'd trn newlines into spaces, otherwise a word break across a
> >> line like this:
> >>
> >>  <p> some words
> >>  here</p>
> >>
> >> would become
> >>
> >>  <p> some wordshere</p>
> >>
> >> So:
> >>
> >>  ( tr '\012' ' ' < data.html ; echo ) | sed other-sed-work-now....
> >>
> >> Remember, sed is not your only tool.
> >>
> >> | 2. remove the surrounding tags from the text that you want in your
> >> | anchor attributes with something like:
> >> | sed -n -e 's/\(<a[^h]*href="\)\([^"]*\)"\([^>]*>\)/\2/g; p'
> >>
> >> I have my concerns here, specificly the "[^h]". It will match "<a href"
> >> as intended, but it will also match all sorts of other undesired things.
> >>
> >>  <a  *href=
> >>
> >> is more reliable, matching spaces. It does presume no TAB characters.
> >>
> >> I would be inclined to use even more tr at the outset, to hammer the
> >> text flatter:
> >>
> >>  ( tr '\011\012' ' ' < data.html ; echo ) | tr -s ' ' | sed ...
> >>
> >> So:
> >>  - turn newlines and TABs into spaces
> >>  - turn multiple spaces into a single space
> >>
> >> That way you can write patterns like this:
> >>
> >>  <a href=
> >>
> >> without having to cope with more than one space; it makes the regexps
> >> much easier to write and read.
> >>
> >> Cheers,
> >> --
> >> Cameron Simpson <cs@...> DoD#743
> >> http://www.cskk.ezoshosting.com/cs/
> >>
> >> My venus fly trap is higher up the food chain than I am.
> >>        - simon@... (Simon Klyne)
> >>
> >
> >
> >
> > --
> > Luigi Assom
> >
> > Skype contact: oggigigi
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> > ------------------------------------
> >
> > --
> > Yahoo! Groups Links
> >
> >
> >
> 
> 
> 
> -- 
> joe gain
> 
> jacob-burckhardt-str. 16
> 78464 konstanz
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> 
> +49 (0)7531 60389
> 
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>