\typeout{msg}
Prints msg on the terminal and in the log file. Commands
in msg that are defined with \newcommand or
\renewcommand are replaced by their definitions before being
printed.
LaTeX's usual rules for treating multiple spaces as
a single space and ignoring spaces after a command name apply to
msg. A \space command in msg causes a single space
to be printed. A ^^J in msg prints a newline.