Info Catalog
screen: Message Line
screen: Hardware Status Line
17.1 Using the message line from your program
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The message line facility can be used by an application running in the
current window by means of the ANSI "Privacy message" control sequence.
For instance, from within the shell, try something like:
echo "^[^Hello world from window $WINDOW^[\"
where '^[' is ASCII ESC and the '^' that follows it is a literal
caret or up-arrow.