How can I cut(1) camelcase words? - bash

Question

Is there an easy way in Bash to split a camelcased word into its constituent words?
For example, I want to split aCertainCamelCasedWord into 'a Certain Camel Cased Word' and be able to select those fields that interest me. This is trivially done with cut(1) when the word separator is the underscore, but how can I do this when the word is camelcased?

Answer 1

sed 's/\([A-Z]\)/ \1/g'
Captures each capital letter and substitutes a leading space with the capture for the whole stream.
$ echo "aCertainCamelCasedWord" | sed 's/\([A-Z]\)/ \1/g'
a Certain Camel Cased Word

Answer 2

This solution works if you need to not split up words that are all caps. For example, using the top answer you'll get:
$ echo 'FAQPage' | sed 's/\([A-Z]\)/ \1/g'
F A Q Page
But instead with my solution, you'll get:
$ echo 'FAQPage' | sed 's/\([A-Z][^A-Z]\)/ \1/g'
FAQ Page
Note: This does not work correctly when there is a second instance of multiple uppercase words, for example:
$ echo 'FAQPageOneReplacedByFAQPageTwo' | sed 's|\([A-Z][^A-Z]\)| \1|g'
FAQ Page One Replaced ByFAQ Page Two

Answer 3

This answer does not work correctly when there is a second instance of multiple uppercase
echo 'FAQPageOneReplacedByFAQPageTwo' | sed 's|\([A-Z][^A-Z]\)| \1|g'
FAQ Page One Replaced ByFAQ Page Two
So and additional expression is required for that
echo 'FAQPageOneReplacedByFAQPageTwo' | sed -e 's|\([A-Z][^A-Z]\)| \1|g' -e 's|\([a-z]\)\([A-Z]\)|\1 \2|g'
FAQ Page One Replaced By FAQ Page Two

Answer 4

Pure Bash:
name="aCertainCamelCasedWord"
declare -a word # the word array
counter1=0 # count characters
counter2=0 # count words
while [ $counter1 -lt ${#name} ] ; do
nextchar=${name:${counter1}:1}
if [[ $nextchar =~ [[:upper:]] ]] ; then
((counter2++))
word[${counter2}]=$nextchar
else
word[${counter2}]=${word[${counter2}]}$nextchar
fi
((counter1++))
done
echo -e "'${word[#]}'"