Unique emails in string

Question

I have a string with emails, some duplicated. For example only:

"[email protected],[email protected],[email protected],[email protected],[email protected]"

I would like string to contain only unique emails, comma separated. Result should be:

"[email protected],[email protected],[email protected]"

Any easy way to do this?

P.S. emails vary, and I don't know what they will contain.

Answer 1

How about this:

echo "[email protected],[email protected],[email protected],[email protected],[email protected]" |
  tr ',' '\n' |
  sort |
  uniq |
  tr '\n' ',' |
  sed -e 's/,$//'

I convert the separating commas into newlines so that I can then use tools (like sort, uniq, and grep) that work with lines.