Programming Perl, 3rd Edition

Unattended Execution

During startup, options are initialized from $ENV{PERLDB_OPTS}. You may place the initialization options TTY, noTTY, ReadLine, and NonStop there.

If your init file contains:

parse_options("NonStop=1 LineInfo=tperl.out AutoTrace");

then your program will run without human intervention, putting trace information into the file db.out. (If you interrupt it, you'd better reset LineInfo to /dev/tty if you expect to see anything.)

The following options can be specified only at startup. To set them in your init file, call parse_options("OPT=VAL").

TTY

The terminal to use for debugging I/O.

noTTY

If set, the debugger goes into NonStop mode and will not connect to a terminal. If interrupted (or if control goes to the debugger via explicit setting of $DB::signal or $DB::single from the Perl program), it connects to a terminal specified in the TTY option at startup, or to a terminal found at run time using the Term::Rendezvous module of your choice.

This module should implement a method named new that returns an object with two methods: IN and OUT. These should return filehandles for the debugger to use its input and output correspondingly. The new method should inspect an argument containing the value of $ENV{PERLDB_NOTTY} at startup, or "/tmp/perldbtty$$" otherwise. This file is not inspected for proper ownership or wide-open write access, so security hazards are theoretically possible.

ReadLine

If false, ReadLine support in the debugger is disabled in order to debug applications ...