perldebug.pod

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=item o booloption ...
X<debugger command, o>

Set each listed Boolean option to the value C<1>.

=item o anyoption? ...
X<debugger command, o>

Print out the value of one or more options.

=item o option=value ...
X<debugger command, o>

Set the value of one or more options.  If the value has internal
whitespace, it should be quoted.  For example, you could set C<o
pager="less -MQeicsNfr"> to call B<less> with those specific options.
You may use either single or double quotes, but if you do, you must
escape any embedded instances of same sort of quote you began with,
as well as any escaping any escapes that immediately precede that
quote but which are not meant to escape the quote itself.  In other
words, you follow single-quoting rules irrespective of the quote;
eg: C<o option='this isn\'t bad'> or C<o option="She said, \"Isn't
it?\"">.

For historical reasons, the C<=value> is optional, but defaults to
1 only where it is safe to do so--that is, mostly for Boolean
options.  It is always better to assign a specific value using C<=>.
The C<option> can be abbreviated, but for clarity probably should
not be.  Several options can be set together.  See L<"Configurable Options">
for a list of these.

=item < ?
X<< debugger command, < >>

List out all pre-prompt Perl command actions.

=item < [ command ]
X<< debugger command, < >>

Set an action (Perl command) to happen before every debugger prompt.
A multi-line command may be entered by backslashing the newlines.

=item < *
X<< debugger command, < >>

Delete all pre-prompt Perl command actions.

=item << command
X<< debugger command, << >>

Add an action (Perl command) to happen before every debugger prompt.
A multi-line command may be entered by backwhacking the newlines.

=item > ?
X<< debugger command, > >>

List out post-prompt Perl command actions.

=item > command
X<< debugger command, > >>

Set an action (Perl command) to happen after the prompt when you've
just given a command to return to executing the script.  A multi-line
command may be entered by backslashing the newlines (we bet you
couldn't have guessed this by now).

=item > *
X<< debugger command, > >>

Delete all post-prompt Perl command actions.

=item >> command
X<<< debugger command, >> >>>

Adds an action (Perl command) to happen after the prompt when you've
just given a command to return to executing the script.  A multi-line
command may be entered by backslashing the newlines.

=item { ?
X<debugger command, {>

List out pre-prompt debugger commands.

=item { [ command ]

Set an action (debugger command) to happen before every debugger prompt.
A multi-line command may be entered in the customary fashion.

Because this command is in some senses new, a warning is issued if
you appear to have accidentally entered a block instead.  If that's
what you mean to do, write it as with C<;{ ... }> or even
C<do { ... }>.

=item { *
X<debugger command, {>

Delete all pre-prompt debugger commands.

=item {{ command
X<debugger command, {{>

Add an action (debugger command) to happen before every debugger prompt.
A multi-line command may be entered, if you can guess how: see above.

=item ! number
X<debugger command, !>

Redo a previous command (defaults to the previous command).

=item ! -number
X<debugger command, !>

Redo number'th previous command.

=item ! pattern
X<debugger command, !>

Redo last command that started with pattern.
See C<o recallCommand>, too.

=item !! cmd
X<debugger command, !!>

Run cmd in a subprocess (reads from DB::IN, writes to DB::OUT) See
C<o shellBang>, also.  Note that the user's current shell (well,
their C<$ENV{SHELL}> variable) will be used, which can interfere
with proper interpretation of exit status or signal and coredump
information.

=item source file
X<debugger command, source>

Read and execute debugger commands from I<file>.
I<file> may itself contain C<source> commands.

=item H -number
X<debugger command, H>

Display last n commands.  Only commands longer than one character are
listed.  If I<number> is omitted, list them all.

=item q or ^D
X<debugger command, q>
X<debugger command, ^D>

Quit.  ("quit" doesn't work for this, unless you've made an alias)
This is the only supported way to exit the debugger, though typing
C<exit> twice might work.

Set the C<inhibit_exit> option to 0 if you want to be able to step
off the end the script.  You may also need to set $finished to 0
if you want to step through global destruction.

=item R
X<debugger command, R>

Restart the debugger by C<exec()>ing a new session.  We try to maintain
your history across this, but internal settings and command-line options
may be lost.

The following setting are currently preserved: history, breakpoints,
actions, debugger options, and the Perl command-line
options B<-w>, B<-I>, and B<-e>.

=item |dbcmd
X<debugger command, |>

Run the debugger command, piping DB::OUT into your current pager.

=item ||dbcmd
X<debugger command, ||>

Same as C<|dbcmd> but DB::OUT is temporarily C<select>ed as well.

=item = [alias value]
X<debugger command, =>

Define a command alias, like

    = quit q

or list current aliases.

=item command

Execute command as a Perl statement.  A trailing semicolon will be
supplied.  If the Perl statement would otherwise be confused for a
Perl debugger, use a leading semicolon, too.

=item m expr
X<debugger command, m>

List which methods may be called on the result of the evaluated
expression.  The expression may evaluated to a reference to a
blessed object, or to a package name.

=item M
X<debugger command, M>

Displays all loaded modules and their versions


=item man [manpage]
X<debugger command, man>

Despite its name, this calls your system's default documentation
viewer on the given page, or on the viewer itself if I<manpage> is
omitted.  If that viewer is B<man>, the current C<Config> information
is used to invoke B<man> using the proper MANPATH or S<B<-M>
I<manpath>> option.  Failed lookups of the form C<XXX> that match
known manpages of the form I<perlXXX> will be retried.  This lets
you type C<man debug> or C<man op> from the debugger.

On systems traditionally bereft of a usable B<man> command, the
debugger invokes B<perldoc>.  Occasionally this determination is
incorrect due to recalcitrant vendors or rather more felicitously,
to enterprising users.  If you fall into either category, just
manually set the $DB::doccmd variable to whatever viewer to view
the Perl documentation on your system.  This may be set in an rc
file, or through direct assignment.  We're still waiting for a
working example of something along the lines of:

    $DB::doccmd = 'netscape -remote http://something.here/';

=back

=head2 Configurable Options

The debugger has numerous options settable using the C<o> command,
either interactively or from the environment or an rc file.
(./.perldb or ~/.perldb under Unix.)


=over 12

=item C<recallCommand>, C<ShellBang>
X<debugger option, recallCommand>
X<debugger option, ShellBang>

The characters used to recall command or spawn shell.  By
default, both are set to C<!>, which is unfortunate.

=item C<pager>
X<debugger option, pager>

Program to use for output of pager-piped commands (those beginning
with a C<|> character.)  By default, C<$ENV{PAGER}> will be used.
Because the debugger uses your current terminal characteristics
for bold and underlining, if the chosen pager does not pass escape
sequences through unchanged, the output of some debugger commands
will not be readable when sent through the pager.

=item C<tkRunning>
X<debugger option, tkRunning>

Run Tk while prompting (with ReadLine).

=item C<signalLevel>, C<warnLevel>, C<dieLevel>
X<debugger option, signalLevel> X<debugger option, warnLevel>
X<debugger option, dieLevel>

Level of verbosity.  By default, the debugger leaves your exceptions
and warnings alone, because altering them can break correctly running
programs.  It will attempt to print a message when uncaught INT, BUS, or
SEGV signals arrive.  (But see the mention of signals in L<BUGS> below.)

To disable this default safe mode, set these values to something higher
than 0.  At a level of 1, you get backtraces upon receiving any kind
of warning (this is often annoying) or exception (this is
often valuable).  Unfortunately, the debugger cannot discern fatal
exceptions from non-fatal ones.  If C<dieLevel> is even 1, then your
non-fatal exceptions are also traced and unceremoniously altered if they
came from C<eval'ed> strings or from any kind of C<eval> within modules
you're attempting to load.  If C<dieLevel> is 2, the debugger doesn't
care where they came from:  It usurps your exception handler and prints
out a trace, then modifies all exceptions with its own embellishments.
This may perhaps be useful for some tracing purposes, but tends to hopelessly
destroy any program that takes its exception handling seriously.

=item C<AutoTrace>
X<debugger option, AutoTrace>

Trace mode (similar to C<t> command, but can be put into
C<PERLDB_OPTS>).

=item C<LineInfo>
X<debugger option, LineInfo>

File or pipe to print line number info to.  If it is a pipe (say,
C<|visual_perl_db>), then a short message is used.  This is the
mechanism used to interact with a slave editor or visual debugger,
such as the special C<vi> or C<emacs> hooks, or the C<ddd> graphical
debugger.

=item C<inhibit_exit>
X<debugger option, inhibit_exit>

If 0, allows I<stepping off> the end of the script.

=item C<PrintRet>
X<debugger option, PrintRet>

Print return value after C<r> command if set (default).

=item C<ornaments>
X<debugger option, ornaments>

Affects screen appearance of the command line (see L<Term::ReadLine>).
There is currently no way to disable these, which can render
some output illegible on some displays, or with some pagers.
This is considered a bug.

=item C<frame>
X<debugger option, frame>

Affects the printing of messages upon entry and exit from subroutines.  If
C<frame & 2> is false, messages are printed on entry only. (Printing
on exit might be useful if interspersed with other messages.)

If C<frame & 4>, arguments to functions are printed, plus context
and caller info.  If C<frame & 8>, overloaded C<stringify> and
C<tie>d C<FETCH> is enabled on the printed arguments.  If C<frame
& 16>, the return value from the subroutine is printed.

The length at which the argument list is truncated is governed by the
next option:

=item C<maxTraceLen>
X<debugger option, maxTraceLen>

Length to truncate the argument list when the C<frame> option's
bit 4 is set.

=item C<windowSize>
X<debugger option, windowSize>

Change the size of code list window (default is 10 lines).

=back

The following options affect what happens with C<V>, C<X>, and C<x>
commands:

=over 12

=item C<arrayDepth>, C<hashDepth>
X<debugger option, arrayDepth> X<debugger option, hashDepth>

Print only first N elements ('' for all).

=item C<dumpDepth>
X<debugger option, dumpDepth>

Limit recursion depth to N levels when dumping structures.
Negative values are interpreted as infinity.  Default: infinity.

=item C<compactDump>, C<veryCompact>
X<debugger option, compactDump> X<debugger option, veryCompact>

Change the style of array and hash output.  If C<compactDump>, short array
may be printed on one line.

=item C<globPrint>
X<debugger option, globPrint>

Whether to print contents of globs.

=item C<DumpDBFiles>
X<debugger option, DumpDBFiles>

Dump arrays holding debugged files.

=item C<DumpPackages>
X<debugger option, DumpPackages>

Dump symbol tables of packages.

=item C<DumpReused>
X<debugger option, DumpReused>

Dump contents of "reused" addresses.

=item C<quote>, C<HighBit>, C<undefPrint>
X<debugger option, quote> X<debugger option, HighBit>
X<debugger option, undefPrint>

Change the style of string dump.  The default value for C<quote>
is C<auto>; one can enable double-quotish or single-quotish format