A.4. Environment Variables

The following environment variables affect the operation of the debugger:

PERL5DB

This contains the code that starts the debugger; if absent, it defaults to BEGIN

{ require 'perl5db.pl' }.

PERLDB_OPTS

This variable can contain initialization commands using options, which may, for instance, cause the debugger to run noninteractively and dump tracing information to a file. See the perldebug POD page for much more information.

PERLDB_RESTART

If this variable is defined, the debugger will then look for environment variables whose names begin with any of the following:

PERLDB_VISITED
PERLDB_HIST
PERLDB_ON_LOAD
PERLDB_POSTPONE
PERLDB_INC
PERLDB_FILE
PERLDB_OPT
PRELDB_PRETYPE
PERLDB_PRE
PERLDB_POST
PERLDB_TYPEAHEAD

This is how the debugger maintains state across restarts, and you should not change any of those variables. It would be fairly unlikely to do this by accident, of course.

PERLDB_NOTTY

This is used to specify a terminal to connect to after a noninteractive start. See the perldebug page for more information.