Changing case in Vim
See the following methods:
~ : Changes the case of current character
guu : Change current line from upper to lower.
gUU : Change current LINE from lower to upper.
guw : Change to end of current WORD from upper to lower.
guaw : Change all of current WORD to lower.
gUw : Change to end of current WORD from lower to upper.
gUaw : Change all of current WORD to upper.
g~~ : Invert case to entire line
g~w : Invert case to current WORD
guG : Change to lowercase until the end of document.
gU) : Change until end of sentence to upper case
gu} : Change to end of paragraph to lower case
gU5j : Change 5 lines below to upper case
gu3k : Change 3 lines above to lower case
Visual select the text, then U for uppercase or u for lowercase. To swap all casing in a visual selection, press ~ (tilde).
Without using a visual selection, gU<motion>
will make the characters in motion
uppercase, or use gu<motion>
for lowercase.
For more of these, see Section 3 in Vim's change.txt help file.