unix sed substitute nth occurence misfunction?

Question

Let\'s say I have a string which contains multiple occurences of the letter Z. For example: aaZbbZccZ. I want to print parts of that string, each time until the nex

Answer 1

Below sed works closely to what you are looking for, except it removes also the last Z.

$echo aaZbbZccZdd | sed -e 's/Z[^Z]*//1g;s/$/Z/'
aaZ

$echo aaZbbZccZdd | sed -e 's/Z[^Z]*//2g;s/$/Z/'
aaZbbZ

$echo aaZbbZccZdd | sed -e 's/Z[^Z]*//3g;s/$/Z/'
aaZbbZccZ

$echo aaZbbZccZdd | sed -e 's/Z[^Z]*//4g;s/$/Z/'
aaZbbZccZddZ

Edit: Modified according to Aaron suggestion.

Edit2: If you don't know how many Z there are in the string it's safer to use below command. Otherwise additional Z is added at the end.
-r - enables regular expressions
-e - separates sed operations, the same as ; but easier to read in my opinion.

$echo aaZbbZccZddZ | sed -r -e 's/Z[^Z]*//1g' -e 's/([^Z])$/\1Z/'
aaZ

$echo aaZbbZccZddZ | sed -r -e 's/Z[^Z]*//2g' -e 's/([^Z])$/\1Z/'
aaZbbZ

$echo aaZbbZccZddZ | sed -r -e 's/Z[^Z]*//3g' -e 's/([^Z])$/\1Z/'
aaZbbZccZ

$echo aaZbbZccZddZ | sed -r -e 's/Z[^Z]*//4g' -e 's/([^Z])$/\1Z/'
aaZbbZccZddZ

$echo aaZbbZccZddZ | sed -r -e 's/Z[^Z]*//5g' -e 's/([^Z])$/\1Z/'
aaZbbZccZddZ