Question

I am trying to remove duplicate numbers within parentheses using sed.

So I have the following string:

Abdc 1234 1234 (5678) (5678) (9012) (9012) (3456)

I want to use sed to remove any 4-digit numbers within the parentheses, including the parentheses. So my string should look like this:

Abdc 1234 1234 (5678) (9012) (3456)

In this case the “(5678)” and “(9012)” were removed because they were 4-digit numbers within parentheses that repeated. The “1234” numbers were not removed because they were not within parenthesis. The “(3456)” was not removed because it was not repeating.

Answer 1

I do not know how to do this with sed but you could try the following with awk:

$  echo "Abdc 1234 1234 (5678) (5678) (9012) (9012) (3456)" | awk '
   {
     for(i=1;i<=NF;i++) { 
       if(substr($i,0,1) != "(" || (seen[$i] != 1)) {
         seen[$i]=1;
         printf "%s ",$i
       }
     };
     print ""
   }'

Output:

Abdc 1234 1234 (5678) (9012) (3456) 

This loops through the line fields then prints each field only if it has never been seen before or if it is not starting with (.