Issue
I have some text which may have either "Regular sentence case" or "Title Case Text", and I want to convert them to titleCaseText.
Taking the example This Is Not the Real string with the sed command
s/(^|\s)([A-Za-z])/\U\2/g
I get the output
ThisIsNotTheRealString
How can I make the first T to be lowercase t?
Solution
You may match the first uppercase letter with ^([A-Z]):
sed -E 's/^([A-Z])|[[:blank:]]+([A-Za-z])/\l\1\U\2/g'
Or
sed -E 's/^([[:upper:]])|[[:blank:]]+([[:alpha:]])/\l\1\U\2/g'
Then, turn the Group 1 value to lower case, and the second group (as you are already doing) to upper case. See the online demo.
Details
^([[:upper:]])- match the start of the line and then capture an uppercase letter into Group 1|- or[[:blank:]]+- match 1 or more horizontal whitespace chars([[:alpha:]])- and then capture any letter into Group 2
The \l\1 will turn the Group 1 value to lower case and \U\2 will turn the value in Group 2 to upper case.
Answered By - Wiktor Stribiżew