Linux SED RegEx replace, but keep wildcards

Question

If I have a string that contains this somewhere (Foo could be anything):

<tag>Foo</tag>

How would I, using SED and RegEx, replace it with this:

[tag]Foo[/tag]

My failed attempt:

echo "<tag>Foo</tag>" | sed "s/<tag>\(.*\)<\\/tag>/[tag]\1[\\/tag]"

Answer 1

Your regex is missing the terminating /

$ echo "<tag>Foo</tag>" | sed "s/<tag>\(.*\)<\\/tag>/[tag]\1[\\/tag]/"
[tag]Foo[/tag]

Answer 2

With this you can replace all types of tags and don't have to be tag specific.

$echo "<tag>Foo</tag>" | sed "s/[^<]*<\([^>]*\)>\([^<]*\)<\([^>]*\)>/[\1]\2[\3]/"

hope this helps.