5 fix accidental downvote
source | link

Using Unix KSH 27 28 32 27 bytes (or 21 if we only count inside sed command)

Thanks to the suggestions of others :) Appreciated.

.. I got down to this:

sed 's/[^AEIOUÅÄÖ ]/&o&/ig'

(allowed for spaces and Swedish characters)

echo "hello" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
hohelollolo
echo "HELLO" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
HoHELoLLoLO
echo "QuIcKlY Now" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
QoQuIcocKoKlolYoY NoNowow

Using Unix KSH 27 28 32 27 bytes (or 21 if we only count inside sed command)

Thanks to the suggestions of others :) Appreciated.

.. I got down to this:

sed 's/[^AEIOUÅÄÖ ]/&o&/ig'

(allowed for spaces and Swedish characters)

echo "hello" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
hohelollolo
echo "HELLO" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
HoHELoLLoLO
echo "QuIcKlY Now" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
QoQuIcocKoKlolYoY NoNowow

Using Unix KSH 27 28 32 27 bytes (or 21 if we only count inside sed command)

Thanks to the suggestions of others :) Appreciated.

.. I got down to this:

sed 's/[^AEIOUÅÄÖ ]/&o&/ig'

(allowed for spaces and Swedish characters)

echo "hello" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
hohelollolo
echo "HELLO" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
HoHELoLLoLO
echo "QuIcKlY Now" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
QoQuIcocKoKlolYoY NoNowow
4 added 105 characters in body
source | link

Using Unix KSH 27 28 3232 27 bytes (or 21 if we only count inside sed command)

Thanks to the suggestions of others :) Appreciated.

.. I got down to this:

sed 's/[BCDFGHJ-NP-TV-Z][^AEIOUÅÄÖ ]/&o&/ig'

(allowed for spaces and Swedish characters)

echo "hello" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
hohelollolo
echo "HELLO" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
HoHELoLLoLO
echo "QuIcKlY Now" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
QoQuIcocKoKlolYoY NoNowow

Using Unix KSH 27 28 32 bytes

.. I got down to this:

sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'

(allowed for spaces and Swedish characters)

echo "hello" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
hohelollolo
echo "HELLO" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
HoHELoLLoLO
echo "QuIcKlY Now" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
QoQuIcocKoKlolYoY NoNowow

Using Unix KSH 27 28 32 27 bytes (or 21 if we only count inside sed command)

Thanks to the suggestions of others :) Appreciated.

.. I got down to this:

sed 's/[^AEIOUÅÄÖ ]/&o&/ig'

(allowed for spaces and Swedish characters)

echo "hello" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
hohelollolo
echo "HELLO" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
HoHELoLLoLO
echo "QuIcKlY Now" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
QoQuIcocKoKlolYoY NoNowow
3 deleted 48 characters in body
source | link

Using Unix KSH 27 2828 32 bytes

.. I got down to this:

sed 's/[^ aeiouAEIOU][BCDFGHJ-NP-TV-Z]/&o&/g'ig'

(allowed for spaces and Swedish characters)

But can't seem to get anything to work for case insensitive (to help shave off those 5 AEIOU bytes :(

echo "hello" | sed 's/[^ aeiouAEIOU][BCDFGHJ-NP-TV-Z]/&o&/g'ig'
hohelollolo
echo "HELLO" | sed 's/[^ aeiouAEIOU][BCDFGHJ-NP-TV-Z]/&o&/g'ig'
HoHELoLLoLO
echo "QuIcKlY Now" | sed 's/[^ aeiouAEIOU][BCDFGHJ-NP-TV-Z]/&o&/g'ig'
QoQuIcocKoKlolYoY NoNowow

Using Unix KSH 27 28 bytes

.. I got down to this:

sed 's/[^ aeiouAEIOU]/&o&/g'

(allowed for spaces)

But can't seem to get anything to work for case insensitive (to help shave off those 5 AEIOU bytes :(

echo "hello" | sed 's/[^ aeiouAEIOU]/&o&/g'
hohelollolo
echo "HELLO" | sed 's/[^ aeiouAEIOU]/&o&/g'
HoHELoLLoLO
echo "QuIcKlY Now" | sed 's/[^ aeiouAEIOU]/&o&/g'
QoQuIcocKoKlolYoY NoNowow

Using Unix KSH 27 28 32 bytes

.. I got down to this:

sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'

(allowed for spaces and Swedish characters)

echo "hello" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
hohelollolo
echo "HELLO" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
HoHELoLLoLO
echo "QuIcKlY Now" | sed 's/[BCDFGHJ-NP-TV-Z]/&o&/ig'
QoQuIcocKoKlolYoY NoNowow
2 added 1 character in body
source | link
1
source | link