sed to ignore a pattern as well as match a pattern in same line

user_2074310 0
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Input file

<a href="perl.html">perl</a>     <a href="http://zoidberg.sourceforge.net/out.html">http://zoidberg.sourceforge.net</a>
<a href="zoiduser.html">zoiduser</a>    <a href="perl.html">perl</a>     <a href="http://zoidberg.sourceforge.net/sample.html">http://zoidberg.sourceforge.net</a>

I need to only remove .HTML extension from below URL from above file:

<a href="perl.html">perl</a>
<a href="zoiduser.html">zoiduser</a>

So that the final output should look like:

<a href="perl">perl</a>     <a href="http://zoidberg.sourceforge.net/out.html">http://zoidberg.sourceforge.net</a>
<a href="zoiduser">zoiduser</a>    <a href="perl.html">perl</a>     <a href="http://zoidberg.sourceforge.net/sample.html">http://zoidberg.sourceforge.net</a>

This is what I am doing:

sed '/"http\|"www\|"mailto/ ! s|\(.html\)||g' file

But it ignores the line as soon as it matches the first pattern i.e. avoid URLs that start with "http|"www|"mailto.

sed
3 Answers

You can use

sed -E 's/("(http|www|mailto)[^"]*")|\.html/\1/g' file

Details:

  • -E - enables POSIX ERE syntax
  • ("(http|www|mailto)[^"]*") - Group 1 (\1): " and then either http, www, or mailto and then zero or more chars other than " and then a "
  • | - or
  • \.html - .html string.

The replacement is Group 1 values.

See the online demo:

#!/bin/bash
s='<a href="perl.html">perl</a>     <a href="http://zoidberg.sourceforge.net/out.html">http://zoidberg.sourceforge.net</a>
<a href="zoiduser.html">zoiduser</a>    <a href="perl.html">perl</a>     <a href="http://zoidberg.sourceforge.net/sample.html">http://zoidberg.sourceforge.net</a>'
sed -E 's/("(http|www|mailto)[^"]*")|\.html/\1/g' <<< "$s"

Output:

<a href="perl">perl</a>     <a href="http://zoidberg.sourceforge.net/out.html">http://zoidberg.sourceforge.net</a>
<a href="zoiduser">zoiduser</a>    <a href="perl">perl</a>     <a href="http://zoidberg.sourceforge.net/sample.html">http://zoidberg.sourceforge.net</a>
user_38329700

It is not recommended to parse HTML using shell utilities like sed, awk, perl etc. But if you really have to use negation of certain keywords then I would suggest this perl:

perl -pe 's/"(?!www|http|mailto)([^"]+)\.html/"\1/g' f.html

<a href="perl">perl</a>     <a href="http://zoidberg.sourceforge.net/out.html">http://zoidberg.sourceforge.net</a>
<a href="zoiduser">zoiduser</a>    <a href="perl">perl</a>     <a href="http://zoidberg.sourceforge.net/sample.html">http://zoidberg.sourceforge.net</a>

(?!www|http|mailto) is negative lookahead to fail the match if these keywords appear just after "

user_5482250

With your shown samples only, please try following awk code. Simple explanation would be, checking if line contains <a href="(http|mailto|www): in line and if this condition is TRUE then using sub function to substitute first .html" occurrence with "> and then print that line, next will skip printing lines where conditions are not met. 1 will print lines where conditions are not met.

awk '/<a href="(http|mailto|www):/ && sub(/.html">/,"\">"){print;next} 1' Input_file
user_58665800
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