See the current Perl documentation for ucfirst.
Here is our local, out-dated (pre-5.6) version:
ucfirst - return a string with just the next letter in upper case
ucfirst EXPR
ucfirst
Returns the value of
EXPR with the first character uppercased. This is the
internal function implementing the \u escape in double-quoted strings. Respects current
LC_CTYPE locale if use locale in force. See the perllocale manpage.
If
EXPR is omitted, uses $_.