PCRE regex to sed regex

Question

First of all sorry for my bad english. I'm a german guy.

The code given below is working fine in PHP:

$string = preg_replace('/href="(.*?)(\.|\,)"/i','href="$1"',$string);

Now T need the same for sed. I thought it should be:

sed 's/href="(.*?)(\.|\,)"/href="{$\1}"/g' test.htm

But that gives me this error:

sed: -e expression #1, char 36: invalid reference \1 on `s' command's RHS

Can you clarify what you're trying to match and replace? I don't know PHP regexps as well as I know Linux ones. — Chowlett, Jan 18 '10 at 14:04
im trying to replace wrong urls that have a . or , at the end. so should be replaced with — Seblon, Jan 18 '10 at 14:10

score 3 · Answer 1 · answered Jan 18 '10 at 14:06

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sed does not support non-greedy regex match.

answered Jan 18 '10 at 14:06

Dyno Fu

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Please elaborate on this matter. – Adam Matan Jan 18 '10 at 14:10
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\(.*?\) <--- this is greedy match.(with the question mark "?" ) – ghostdog74 Jan 18 '10 at 14:13
So if sed does not support non-greedy match, it should support greedy match - What am I missing? – Adam Matan Jan 18 '10 at 14:20
@Adam: OP is relying on non-greedy match for RE to work. The RE will most likely end up consuming characters past the end of the href attribute. – outis Jan 18 '10 at 15:21
http://perldoc.perl.org/perlre.html#Regular-Expressions check the "Quantifiers" subsection. – Dyno Fu Jan 19 '10 at 02:02

score 2 · Answer 2 · answered Jan 18 '10 at 14:00

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You need a backslash in front of the parentheses you want to reference, thus

sed 's/href="\(.*?\)(.|\,)"/href="{$\1}"/g' test.htm

answered Jan 18 '10 at 14:00

user231967

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you didn't say what you want to do, just that the regexp failed :) – user231967 Jan 18 '10 at 15:10

score 2 · Accepted Answer · answered Jan 18 '10 at 14:19

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sed -e 's|href=\"\(.[^"][^>]*\)\([.,]\)\">|href="\1">|g' file

answered Jan 18 '10 at 14:19

ghostdog74

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score 0 · Answer 4 · answered Jan 18 '10 at 14:04

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You have to escape the block selector characters ( and ) as follows.

sed 's/href="\(.*?\)\(.|\,\)"/href="{$\1}"/g' test.htm

answered Jan 18 '10 at 14:04

Didier Trosset

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outis · Answer 5 · 2010-01-18T14:27:20.860

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If you want to match a literal ".", you need to escape it or use it in a character class. As an alternative to slashing the capturing parentheses (which you need to do with basic REs), you can use the -E option to tell sed to use extended REs. Lastly, the REs used by sed use \N to refer to subpatterns, where N is a digit.

sed -E "s/href=([\"'])([^\"']*)[.,]\1/href=\1\2\1/i"

This has its own issue that will prevent matches of href attributes that use both types of quotes.

man sed and man re_format will give more information on REs as used in sed.

edited Jan 18 '10 at 14:27

answered Jan 18 '10 at 14:19

outis

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In my version of sed, it uses `-r` to specify extended regular expressions (which do not require escaping parenthesis) instead of `-E`. – tomlogic Mar 27 '12 at 15:16

score 0 · Answer 6 · answered Jan 18 '10 at 14:24

0

here is a solution, it is not prefect, only deal with the situation of one extra "," or "."


sed -r -e 's/href="([^"]*)([.,]+)"/href="\1"/g' test.htm

answered Jan 18 '10 at 14:24

Dyno Fu

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PCRE regex to sed regex

6 Answers6

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