In Bash, what does a # at the end of the default prompt string indicate?

Which variable contains the process ID (PID) of the script while it's running?

Using "awk", what would the output of this command string be? echo "1 2 3" | awk '{for (i=1; i<=NF; i++) s=s+$i};END {print s}'

To run a copy command in a subshell, which syntax would you use?