Using the Command-line Interface to the Debugger

To use the debugger on pre-written code, first make sure the code compiles without errors.
Run the script debug.code in the debugger: perl -d debug.code
The debugger displays and halts just before the first run-time executable statement.
Type 'h' to list the available commands.
- Type 'h h' for a compact listing.
- Precede any command with a pipe symbol to run it through a pager (e.g. '|h')
Type 'p $part' to print the value of the scalar. (Why doesn't this print any value?)

Type 'l' to list the next window of lines.

  DB<1> l
  4==>    $part = 'sparkplug';
  5:      @inventory = ('batteries', 'fluids', 'bolts');
  6:      %lunch =
  7         ( monday => 'soup', tuesday => 'sandwich' );
  8
  9       # now create references to this data
  10:     $ref_part = \$part;
  11:     $ref_inventory = \@inventory;
  12:     $ref_lunch = \%lunch;
  13

==> indicates the next executed line
: indicates a breakable line

Place a break at line 11:
b 11
Step through the code until the breakpoint using the 'c' command.
Repeat the command 'p $part' to print the value of the scalar.
- Repeat a command using the '!command-number' syntax.
- For example, to repeat the 'l' command (shown above as 'DB<1>') use '!1'.
Observe the different ways the 'p' and 'x' commands print the values of the variables @inventory, %lunch, and $ref_part.

Using the Command-line Interface to the Debugger

http://www.keller.com/perladv/1/comline.html Updated Wednesday, 31-Oct-2001 14:22:37 CST Copyright © 1999

http://www.keller.com/perladv/1/comline.html
Updated Wednesday, 31-Oct-2001 14:22:37 CST

Copyright © 1999