Uppercasing First Letter of Words Using SED

Question

How do you replace the first letter of a word into Capital letter, e.g.

Trouble me
Gold rush brides

into

Trouble Me
Gold R         


        

Answer 1

Use the following sed command for capitalizing the first letter of the each word.

echo -e "Trouble me \nGold rush brides" | sed -r 's/\<./\U&/g'

output

Trouble Me
Gold Rush Brides

The -r switch tells sed to use extended regular expressions. The instructions to sed then tell it to "search and replace" (the s at the beginning) the pattern \<. with the pattern \U& globally, i.e. all instances in every line (that's the g modifier at the end). The pattern we're searching for is \<. which is looking for a word boundary (\<) followed by any character (.). The replacement pattern is \U&, where \U instructs sed to make the following text uppercase and & is a synonym for \0, which refers to "everything that was matched". In this case, "everything that was matched" is just what the . matched, as word boundaries are not included in the matches (instead, they are anchors). What . matched is just one character, so this is what is upper cased.