Unix SED - get title then set it another place

Question

I have a HTML file like this:

<html><head>
<title>My Title</title>
</head>
<body>
Title of this page: PAGE_TITLE
</body>
</html>

How can replace PAGE_TITLE on title?

I try this command:

sed -i 's/\(.*?<title>\)\(.*?\)\(<\/title>.*?\)PAGE_TITLE/\1\2\3\2/' page.html

but it doesn't work.

Are you required to use `sed`? `awk` would be an easier tool for this. — Barmar, Jan 22 '15 at 17:00

score 3 · Answer 1 · edited May 23 '17 at 12:28

3

Don't use regex to parse HTML. Using a proper parser & xpath :

# fetch title string
title=$(xml sel -t -v /html/head/title file.html)
# edit file in-place
xml ed -L -u '/html/body/text()' -v "Title of this page: $title" file.html

xml is xmlstarlet

Check: RegEx match open tags except XHTML self-contained tags

edited May 23 '17 at 12:28

Community

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1

answered Jan 22 '15 at 17:01

Gilles Quénot

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first query the title: `title=$(xml sel -t -v /html/head/title file.html)` and then use that value in the edit command – glenn jackman Jan 22 '15 at 17:27

score 1 · Accepted Answer · answered Jan 22 '15 at 17:08

1

Using awk:

awk '/<title>/ { title = $0; sub(".*<title>", "", title); sub("</title>.*", "", title)}
     /PAGE_TITLE/ { sub("PAGE_TITLE", title); }
     1' filename > filename.new

answered Jan 22 '15 at 17:08

Barmar

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score 0 · Answer 3 · answered Jan 22 '15 at 17:34

The problem with your sed script is that you are using *? which is an unsupported regex extension. You can get much the same result with [^<>]* instead of .*?.

Also, the <title> element is not allowed inside the HTML <body> so you should not include it; you are creating invalid HTML.

Unix SED - get title then set it another place

3 Answers3