Question

I would need to create a script that uses sed to replace the lower case vowels with upper case vowels and the upper case vowels with lover case ones.
For example if I would have the string “This Is a lOng String” the result should be “ThIs is A long StrIng”.
I tried something like this sed 's/a/A/g ; s/A/a/g' but this will not change a->A and A->a it only replaces the lower case ones..
I know there were similar questions but I couldn’t get it to work so I thought I would ask you..

Answer 1

Use sed‘s y command for transliterating.

sed 'y/aeiouAEIOU/AEIOUaeiou/'

Proof of Concept

$ echo "This Is a lOng String" | sed 'y/aeiouAEIOU/AEIOUaeiou/'
ThIs is A long StrIng