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POCan sed regex simulate lookbehind and lookahead?
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14887007
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2013-02-15T01:24:04.870
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2013-02-15T17:38:29.077
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2013-02-15T17:38:29.077
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I'm trying to write a sed script that will capture all "naked" URL's in a text file and replace them with <code><a href=[URL]>[URL]</a></code>. By "naked" I mean a URL that is not wrapped inside an anchor tag. My initial thought was that I should match URL's that do not have a " or a > in front of them, and also do not have a < or a " after them. However, I am running into difficulty with expressing the concept of "do not have in front of or behind" because as far as I know sed does not have look-ahead or look-behind. Sample Input: <pre><code>[Beginning of File]http://foo.bar arbitrary text http://test.com other text <a href="http://foobar.com">http://foobar.com</a> Nearing end of file!!! http://yahoo.com[End of File] </code></pre> Sample Desired Output: <pre><code>[Beginning of File]<a href="http://foo.bar">http://foo.bar</a> arbitrary text <a href="http://test.com">http://test.com</a> other text <a href="http://foo.bar">http://foo.bar</a> Nearing end of file!!! <a href="http://yahoo.com">http://yahoo.com</a>[End of File] </code></pre> Observe that the third line is unmodified, because it is already inside <code><a href></code>. On the other hand, both the first and second lines are modified. Finally, observe that all non-URL text is unmodified. Ultimately, I am trying to do something like: <pre><code>sed s/[^>"](http:\/\/[^\s]\+)/<a href="\1">\1<\/a>/g 2-7-2013 </code></pre> I began by verifying that the following will correctly match and remove a URL: <pre><code>sed 's/http:\/\/[^\s]\+//g' </code></pre> I then tried this, but it is not able to match URL's that start at the beginning of file / input: <pre><code>sed 's/[^\>"]http:\/\/[^\s]\+//g' </code></pre> Is there a way to work around this in sed, either by simulating lookbehind / lookahead, or explicitly matching beginning of file and end of file?
Tags
<regex><sed><awk><regex-negation><regex-lookarounds>
Title
Can sed regex simulate lookbehind and lookahead?
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1. PO
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1. PTQuestion
UserLastEditorUserId
1. USEd Morton
UserOwnerUserId
1. USmerlin2011
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1. PO
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1. VO
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 POCan sed regex simulate lookbehind and lookahead?
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