regex and sed

[jdh239]

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I haven't used regex with sed before. I have a syntax issue, but don't know how to correct it. Consider the following:
https://regex101.com/r/EF2OLR/1

If I have a variable that contains the string:

mac=00:21:f6:04:16:f3bridge=101498d8ff

I want to manipulate 04:16:f3

I have the following:

echo $i | sed -e 's|(mac=00:21:f6:)((\w{2}:?){3})(bridge=\w+)|\1MYSTUFF\4|g'

I am trying to use backrefs (unsuccessfully). I am sure I have a syntax issue, but don't know how to correct it.

sed: -e expression #1, char 57: invalid reference \4 on `s' command's RHS
sed: -e expression #1, char 57: invalid reference \4 on `s' command's RHS

[jdh239]

Got it.... needed sed -E, not sed -e