X-Git-Url: https://perl5.git.perl.org/perl5.git/blobdiff_plain/1472e7de75222b97d63995edd75ecee5ae79b468..ad4795e78e923065898354b946437030aaeca163:/pod/perldebug.pod diff --git a/pod/perldebug.pod b/pod/perldebug.pod index b711094..89334eb 100644 --- a/pod/perldebug.pod +++ b/pod/perldebug.pod @@ -1,4 +1,5 @@ =head1 NAME +X X perldebug - Perl debugging @@ -8,7 +9,7 @@ First of all, have you tried using the B<-w> switch? If you're new to the Perl debugger, you may prefer to read -L, which is a tutorial introduction to the debugger . +L, which is a tutorial introduction to the debugger. =head1 The Perl Debugger @@ -19,6 +20,7 @@ source code, set breakpoints, get stack backtraces, change the values of variables, etc. This is so convenient that you often fire up the debugger all by itself just to test out Perl constructs interactively to see what they do. For example: +X<-d> $ perl -d -e 42 @@ -39,6 +41,12 @@ Any command not recognized by the debugger is directly executed (C'd) as Perl code in the current package. (The debugger uses the DB package for keeping its own state information.) +Note that the said C is bound by an implicit scope. As a +result any newly introduced lexical variable or any modified +capture buffer content is lost after the eval. The debugger is a +nice environment to learn Perl, but if you interactively experiment using +material which should be in the same scope, stuff it in one line. + For any text entered at the debugger prompt, leading and trailing whitespace is first stripped before further processing. If a debugger command coincides with some function in your own program, merely precede the @@ -46,30 +54,59 @@ function with something that doesn't look like a debugger command, such as a leading C<;> or perhaps a C<+>, or by wrapping it with parentheses or braces. +=head2 Calling the Debugger + +There are several ways to call the debugger: + +=over 4 + +=item perl -d program_name + +On the given program identified by C. + +=item perl -d -e 0 + +Interactively supply an arbitrary C using C<-e>. + +=item perl -d:Ptkdb program_name + +Debug a given program via the C GUI. + +=item perl -dt threaded_program_name + +Debug a given program using threads (experimental). + +=back + =head2 Debugger Commands -The debugger understands the following commands: +The interactive debugger understands the following commands: =over 12 +=item h +X + +Prints out a summary help message + =item h [command] -Prints out a help message. +Prints out a help message for the given debugger command. -If you supply another debugger command as an argument to the C command, -it prints out the description for just that command. The special -argument of C produces a more compact help listing, designed to fit -together on one screen. +=item h h -If the output of the C command (or any command, for that matter) scrolls +The special argument of C produces the entire help page, which is quite long. + +If the output of the C command (or any command, for that matter) scrolls past your screen, precede the command with a leading pipe symbol so that it's run through your pager, as in - DB> |h + DB> |h h -You may change the pager which is used via C command. +You may change the pager which is used via C command. =item p expr +X Same as C in the current package. In particular, because this is just Perl's own C function, this means that nested @@ -78,19 +115,26 @@ data structures and objects are not dumped, unlike with the C command. The C filehandle is opened to F, regardless of where STDOUT may be redirected to. -=item x expr +=item x [maxdepth] expr +X -Evaluates its expression in list context and dumps out the result -in a pretty-printed fashion. Nested data structures are printed out -recursively, unlike the real C function in Perl. +Evaluates its expression in list context and dumps out the result in a +pretty-printed fashion. Nested data structures are printed out +recursively, unlike the real C function in Perl. When dumping +hashes, you'll probably prefer 'x \%h' rather than 'x %h'. See L if you'd like to do this yourself. The output format is governed by multiple options described under L<"Configurable Options">. +If the C is included, it must be a numeral I; the value is +dumped only I levels deep, as if the C option had been +temporarily set to I. + =item V [pkg [vars]] +X -Display all (or some) variables in package (defaulting to C
) +Display all (or some) variables in package (defaulting to C
) using a data pretty-printer (hashes show their keys and values so you see what's what, control characters are made printable, etc.). Make sure you don't put the type specifier (like C<$>) there, just @@ -103,20 +147,35 @@ Use C<~pattern> and C for positive and negative regexes. This is similar to calling the C command on each applicable var. =item X [vars] +X Same as C. +=item y [level [vars]] +X + +Display all (or some) lexical variables (mnemonic: C variables) +in the current scope or I scopes higher. You can limit the +variables that you see with I which works exactly as it does +for the C and C commands. Requires the C module +version 0.08 or higher; will warn if this isn't installed. Output +is pretty-printed in the same style as for C and the format is +controlled by the same options. + =item T +X X X Produce a stack backtrace. See below for details on its output. =item s [expr] +X X Single step. Executes until the beginning of another statement, descending into subroutine calls. If an expression is supplied that includes function calls, it too will be single-stepped. =item n [expr] +X Next. Executes over subroutine calls, until the beginning of the next statement. If an expression is supplied that includes @@ -124,6 +183,7 @@ function calls, those functions will be executed with stops before each statement. =item r +X Continue until the return from the current subroutine. Dump the return value if the C option is set (default). @@ -133,11 +193,13 @@ Dump the return value if the C option is set (default). Repeat last C or C command. =item c [line|sub] +X Continue, optionally inserting a one-time-only breakpoint at the specified line or subroutine. =item l +X List next window of lines. @@ -159,22 +221,26 @@ List first window of lines from subroutine. I may be a variable that contains a code reference. =item - +X List previous window of lines. -=item w [line] +=item v [line] +X -List window (a few lines) around the current line. +View a few lines of code around the current line. =item . +X Return the internal debugger pointer to the line last executed, and print out that line. =item f filename +X Switch to viewing a different file or C statement. If I -is not a full pathname found in the values of %INC, it is considered +is not a full pathname found in the values of %INC, it is considered a regex. Ced strings (when accessible) are considered to be filenames: @@ -193,27 +259,38 @@ The search is case-insensitive by default. Search backwards for pattern; final ? is optional. The search is case-insensitive by default. -=item L +=item L [abw] +X -List all breakpoints and actions. +List (default all) actions, breakpoints and watch expressions =item S [[!]regex] +X List subroutine names [not] matching the regex. =item t +X Toggle trace mode (see also the C option). =item t expr +X Trace through execution of C. See L for examples. +=item b +X +X + +Sets breakpoint on current line + =item b [line] [condition] +X +X -Set a breakpoint before the given line. If I is omitted, set a -breakpoint on the line about to be executed. If a condition +Set a breakpoint before the given line. If a condition is specified, it's evaluated each time the statement is reached: a breakpoint is taken only if the condition is true. Breakpoints may only be set on lines that begin an executable statement. Conditions @@ -223,36 +300,96 @@ don't use C: b 237 ++$count237 < 11 b 33 /pattern/i +=item b [file]:[line] [condition] +X +X + +Set a breakpoint before the given line in a (possibly different) file. If a +condition is specified, it's evaluated each time the statement is reached: a +breakpoint is taken only if the condition is true. Breakpoints may only be set +on lines that begin an executable statement. Conditions don't use C: + + b lib/MyModule.pm:237 $x > 30 + b /usr/lib/perl5/site_perl/CGI.pm:100 ++$count100 < 11 + =item b subname [condition] +X +X Set a breakpoint before the first line of the named subroutine. I may be a variable containing a code reference (in this case I is not supported). =item b postpone subname [condition] +X +X Set a breakpoint at first line of subroutine after it is compiled. =item b load filename +X +X Set a breakpoint before the first executed line of the I, which should be a full pathname found amongst the %INC values. =item b compile subname +X +X Sets a breakpoint before the first statement executed after the specified subroutine is compiled. -=item d [line] +=item B line +X +X -Delete a breakpoint from the specified I. If I is omitted, deletes -the breakpoint from the line about to be executed. +Delete a breakpoint from the specified I. -=item D +=item B * +X +X Delete all installed breakpoints. +=item disable [file]:[line] +X +X +X + +Disable the breakpoint so it won't stop the execution of the program. +Breakpoints are enabled by default and can be re-enabled using the C +command. + +=item disable [line] +X +X +X + +Disable the breakpoint so it won't stop the execution of the program. +Breakpoints are enabled by default and can be re-enabled using the C +command. + +This is done for a breakpoint in the current file. + +=item enable [file]:[line] +X +X +X + +Enable the breakpoint so it will stop the execution of the program. + +=item enable [line] +X +X +X + +Enable the breakpoint so it will stop the execution of the program. + +This is done for a breakpoint in the current file. + =item a [line] command +X Set an action to be done before the line is executed. If I is omitted, set an action on the line about to be executed. @@ -269,149 +406,192 @@ For example, this will print out $foo every time line a 53 print "DB FOUND $foo\n" -=item a [line] +=item A line +X -Delete an action from the specified line. If I is omitted, delete -the action on the line that is about to be executed. +Delete an action from the specified line. -=item A +=item A * +X Delete all installed actions. +=item w expr +X + +Add a global watch-expression. Whenever a watched global changes the +debugger will stop and display the old and new values. + =item W expr +X -Add a global watch-expression. We hope you know what one of these -is, because they're supposed to be obvious. B: It is far -too easy to destroy your watch expressions by accidentally omitting -the I. +Delete watch-expression -=item W +=item W * +X Delete all watch-expressions. -=item O booloption ... +=item o +X + +Display all options. + +=item o booloption ... +X Set each listed Boolean option to the value C<1>. -=item O anyoption? ... +=item o anyoption? ... +X Print out the value of one or more options. -=item O option=value ... +=item o option=value ... +X Set the value of one or more options. If the value has internal -whitespace, it should be quoted. For example, you could set C to call B 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 or C or C. 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