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

Joe has the truth here. I'm just adding a few remarks.

On 24Apr2012 13:05, Joe Gain <[email protected]> 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 <[email protected]> DoD#743
http://www.cskk.ezoshosting.com/cs/

My venus fly trap is higher up the food chain than I am.
        - [email protected] (Simon Klyne)