Using sed to replace xml attribute

Question

My file contains a line like this:

<virtual-server name="default-host" enable-welcome-root="false">

I want to replace: enable-welcome-root from false to true

Using sed -n 's/.*enable-welcome-root="\([^"]*\).*/\1/p' file I can get the value which is false, but how can I replace it?

You are back reference to wrong group `false`, not to `enable-welcome-root` — Jotne, Mar 28 '15 at 06:34
The mandatory "don't parse xml with regular expressions" link: http://stackoverflow.com/a/1732454/7552 — glenn jackman, Mar 28 '15 at 13:01

score 5 · Accepted Answer · answered Mar 28 '15 at 06:28

This would change from false or true to true

sed -r 's/(enable-welcome-root=")[^"]+"/\1true"/' file
<virtual-server name="default-host" enable-welcome-root="true">

or without -r

sed 's/\(enable-welcome-root="\)[^"]+"/\1true"/'
<virtual-server name="default-host" enable-welcome-root="false">

Use -i to write back to file

score 3 · Answer 2 · answered Mar 28 '15 at 07:11

3

Your string contains no special characters. Thus:

s='<virtual-server name="default-host" enable-welcome-root="false">'
r='<virtual-server name="default-host" enable-welcome-root="true">'
sed -i -e "s/$s/$r/" file

answered Mar 28 '15 at 07:11

Cyrus

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I enjoy that way of separating parts of `sed`: it makes it clearer. – Marc Le Bihan Jun 05 '23 at 04:54

glenn jackman · Answer 3 · 2015-03-28T13:49:45.863

3

Using xmlstarlet, and adding a close tag to your line:

xmlstarlet ed -O -u '//virtual-server/@enable-welcome-root[.="false"]' -v "true" <<END
<virtual-server name="default-host" enable-welcome-root="false">
</virtual-server>
END

<virtual-server name="default-host" enable-welcome-root="true">
</virtual-server>

edited Mar 28 '15 at 13:49

answered Mar 28 '15 at 13:06

glenn jackman

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The question is about using sed. Not another promoted tool. – Marc Le Bihan Jun 04 '23 at 05:33
https://stackoverflow.com/a/1732454/7552 – glenn jackman Jun 04 '23 at 07:05

Using sed to replace xml attribute

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