My god Bakunin, you're a master in sed! Thank you so much for taking the time to write these lines!
OK then, let me try on your sed to see if I understood:
Code:
sed -n '/href.*view more/ s/.*href="\([^"]*\).*/\1/p')
I'll stay with my understanding of the first part of the command. You're actually not passing any command yet to sed. So what you're looking for in:
Code:
'/href.*view more/
is the line that matches "href [any kind of character in between]view more" or to put it another way:
Code:
SED, find me the line that has "href" + some string and "view more"in it.
you get that line:
Code:
<a href="/listing/magnet/ge/ramp-shim/2322185"> view more </a>
Now comes the good part:
Code:
s/.*href="\([^"]*\).*/\1/p'
Within that line, substitute: "[any kind of character before] href=" [following string omitting the possible " characters within the string] by [this same string without " characters that you just found] and print.
but how come the "> view more </a>" portion of the line was left out of the sed? because from what I understand you're including .* which still should include all the characters at the end of the line, shouldn't it?
Thanks as usual!
Best!
EDIT-----
I just tried:
Code:
sed -n '/href.*view more/ s/.*href="\(.*\)/\1/p'
and it gave me:
Code:
/listing/magnet/ge/ramp-shim/2322185"> view more </a>
So I guess that what's happening with your code is that when you tell sed to exclude the " it simply stops at it and do not go on with the rest of the line.
---------- Post updated at 06:08 PM ---------- Previous update was at 04:43 PM ----------
Quote:
Originally Posted by MadeInGermany
Exactly. The first character that matches in the trailing .* is a quote.
As I said, the leading and trailing .* are needed to "match away" the entire line. Otherwise only the matching portion would be substituted.
---------- Post updated at 12:15 ---------- Previous update was at 11:44 ----------
Now to your second requirement. Can give a headache even for experienced guys.
In your example the ' is a problem for the shell, in which you call
Code:
sed -n '...'
There is no problem if you save the sed code in a separate file and run it with
Code:
sed -n -f sed-script result2.txt
And the contents of the sed-script
Code:
/itemprop='brand'/ s/.*'brand'>\([^<]*\).*/\1/p
You can add another match in a second line
Code:
/itemprop='name'/ s/.*'name'>\([^<]*\).*/\1/p
but it won't match if the first match was successful and the input line was substituted.
It is necessary to save and restore the line.
Code:
h
/itemprop='brand'/ s/.*'brand'>\([^<]*\).*/\1/p
g
/itemprop='name'/ s/.*'name'>\([^<]*\).*/\1/p
Another aspect is greediness. The * wants to match as much it can. A leftmost * is most greedy.
That means /.*'branch'/ matches the rightmost 'branch'.
--
Last but not least, the shell method to print a ' within a ' ' string goes like this
Code:
echo 'left'\''right'
Actually it is a concatenation of 'left' and 'right' with a \' in between.
For an embedded sed script it is enough to remember to exchange each literal ' by '\''.
Hey MadeinGermany!
Bakunin's explaination helped me a lot go through your answer but I still got a few questions:
Quote:
In your example the ' is a problem for the shell, in which you call
Code:
sed -n '...'
There is no problem if you save the sed code in a separate file and run it with
Code:
sed -n -f sed-script result2.txt
Why is it a problem for the shell?
When I paste the previous "PHP" (I assume it's PHP) code into a txt (examplesed.txt) for testing the command:
Code:
sed -n '/itemprop='brand'/ s/.*'brand'>\([^<]*\).*/\1/p' examplesed.txt
it yields nothing. There's no output whatsoever...
Quote:
Code:
/itemprop='brand'/ s/.*'brand'>\([^<]*\).*/\1/p
You can add another match in a second line
Code:
/itemprop='name'/ s/.*'name'>\([^<]*\).*/\1/p
but it won't match if the first match was successful and the input line was substituted.
It is necessary to save and restore the line.
Code:
h /itemprop='brand'/ s/.*'brand'>\([^<]*\).*/\1/p g /itemprop='name'/ s/.*'name'>\([^<]*\).*/\1/p
On that one, I'm not sure to follow either... My objective is to integrate these commands within a loop. So I will have the first iteration and it'll write the output to a file, then the second command (with 'name' for instance) > echo to a file and go to the third iteration etc...
Wouldn't that work under that setting?
Quote:
Another aspect is greediness. The * wants to match as much it can. A leftmost * is most greedy.
That means /.*'branch'/ matches the rightmost 'branch'.
I guess that in my case, my problem child would be 'name' that has a first appearance at the beginning of the line.
But in that case couldn't I use 2 right before the 'p' (print command).
I learnt on the web that putting a 1 or a 2 before the p would yield the first or second appearance of the term I'm looking for... wouldn't that work?
All the best!
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