${NAME} Perl-expression

Print value of expression Perl-expression each time the program stops.

Examples:

${NAME} \$a  # Display variable \$a each time we enter debugger
${NAME} join(', ', \@ARGV)  # show values of array \@ARGV

If what you want to do is evaluate a Perl expression or statement once rather than every time the program stops, see eval.

See also undisplay, enable, disable.