CODEWITHSUNDEEP
unixtr
Kamran224
Kamran224

Reputation: 1614

unix tr find and replace

This is the command I'm using on a standard web page I wget from a web site.

tr '<' '\n<' < index.html

however it giving me newlines, but not adding the left broket in again. e.g.

echo "<hello><world>" | tr '<' '\n<' | cat -e

returns

$
hello>$
world>$

instead of

$
<hello>$
<world>$

What's wrong?

Upvotes: 17

Views: 67137

Answers (4)

felix747
felix747

Reputation: 39

The order of where you put your newline is important. Also you can escape the "<".

tr '<' '<\n' < index.html

works as well.

Upvotes: 3

ephemient
ephemient

Reputation: 204926

That's because tr only does character-for-character substitution (or deletion).

Try sed instead.

echo '<hello><world>' | sed -e 's/</\n&/g'

Or awk.

echo '<hello><world>' | awk '{gsub(/</,"\n<",$0)}1'

Or perl.

echo '<hello><world>' | perl -pe 's/</\n</g'

Or ruby.

echo '<hello><world>' | ruby -pe '$_.gsub!(/</,"\n<")'

Or python.

echo '<hello><world>' \
| python -c 'for l in __import__("fileinput").input():print l.replace("<","\n<")'

Upvotes: 35

Dennis Williamson
Dennis Williamson

Reputation: 360345

If you have GNU grep, this may work for you:

grep -Po '<.*?>[^<]*' index.html

which should pass through all of the HTML, but each tag should start at the beginning of the line with possible non-tag text following on the same line.

If you want nothing but tags:

grep -Po '<.*?>' index.html

You should know, however, that it's not a good idea to parse HTML with regexes.

Upvotes: 3

jaypal singh
jaypal singh

Reputation: 77145

Does this work for you? 

awk -F"><" -v OFS=">\n<" '{print $1,$2}'

[jaypal:~/Temp] echo "<hello><world>" | awk -F"><" -v OFS=">\n<" '{$1=$1}1';
<hello>
<world>

You can put a regex / / (lines you want this to happen for) in front of the awk {} action.

Upvotes: 2

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