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<div class="section" id="module-pdb">
<span id="pdb-the-python-debugger"></span><span id="debugger"></span><h1>26.2. <a class="reference internal" href="#module-pdb" title="pdb: The Python debugger for interactive interpreters."><code class="xref py py-mod docutils literal notranslate"><span class="pre">pdb</span></code></a> — The Python Debugger<a class="headerlink" href="#module-pdb" title="Permalink to this headline">¶</a></h1>
<p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/2.7/Lib/pdb.py">Lib/pdb.py</a></p>
<hr class="docutils" />
<p id="index-0">The module <a class="reference internal" href="#module-pdb" title="pdb: The Python debugger for interactive interpreters."><code class="xref py py-mod docutils literal notranslate"><span class="pre">pdb</span></code></a> defines an interactive source code debugger for Python
programs. It supports setting (conditional) breakpoints and single stepping at
the source line level, inspection of stack frames, source code listing, and
evaluation of arbitrary Python code in the context of any stack frame. It also
supports post-mortem debugging and can be called under program control.</p>
<p id="index-1">The debugger is extensible — it is actually defined as the class <a class="reference internal" href="#pdb.Pdb" title="pdb.Pdb"><code class="xref py py-class docutils literal notranslate"><span class="pre">Pdb</span></code></a>.
This is currently undocumented but easily understood by reading the source. The
extension interface uses the modules <a class="reference internal" href="bdb.html#module-bdb" title="bdb: Debugger framework."><code class="xref py py-mod docutils literal notranslate"><span class="pre">bdb</span></code></a> and <a class="reference internal" href="cmd.html#module-cmd" title="cmd: Build line-oriented command interpreters."><code class="xref py py-mod docutils literal notranslate"><span class="pre">cmd</span></code></a>.</p>
<p>The debugger’s prompt is <code class="docutils literal notranslate"><span class="pre">(Pdb)</span></code>. Typical usage to run a program under control
of the debugger is:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">pdb</span>
<span class="gp">>>> </span><span class="kn">import</span> <span class="nn">mymodule</span>
<span class="gp">>>> </span><span class="n">pdb</span><span class="o">.</span><span class="n">run</span><span class="p">(</span><span class="s1">'mymodule.test()'</span><span class="p">)</span>
<span class="go">> <string>(0)?()</span>
<span class="go">(Pdb) continue</span>
<span class="go">> <string>(1)?()</span>
<span class="go">(Pdb) continue</span>
<span class="go">NameError: 'spam'</span>
<span class="go">> <string>(1)?()</span>
<span class="go">(Pdb)</span>
</pre></div>
</div>
<p><code class="file docutils literal notranslate"><span class="pre">pdb.py</span></code> can also be invoked as a script to debug other scripts. For
example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">python</span> <span class="o">-</span><span class="n">m</span> <span class="n">pdb</span> <span class="n">myscript</span><span class="o">.</span><span class="n">py</span>
</pre></div>
</div>
<p>When invoked as a script, pdb will automatically enter post-mortem debugging if
the program being debugged exits abnormally. After post-mortem debugging (or
after normal exit of the program), pdb will restart the program. Automatic
restarting preserves pdb’s state (such as breakpoints) and in most cases is more
useful than quitting the debugger upon program’s exit.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 2.4: </span>Restarting post-mortem behavior added.</p>
</div>
<p>The typical usage to break into the debugger from a running program is to
insert</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">pdb</span><span class="p">;</span> <span class="n">pdb</span><span class="o">.</span><span class="n">set_trace</span><span class="p">()</span>
</pre></div>
</div>
<p>at the location you want to break into the debugger. You can then step through
the code following this statement, and continue running without the debugger using
the <code class="docutils literal notranslate"><span class="pre">c</span></code> command.</p>
<p>The typical usage to inspect a crashed program is:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">pdb</span>
<span class="gp">>>> </span><span class="kn">import</span> <span class="nn">mymodule</span>
<span class="gp">>>> </span><span class="n">mymodule</span><span class="o">.</span><span class="n">test</span><span class="p">()</span>
<span class="gt">Traceback (most recent call last):</span>
File <span class="nb">"<stdin>"</span>, line <span class="m">1</span>, in <span class="n"><module></span>
File <span class="nb">"./mymodule.py"</span>, line <span class="m">4</span>, in <span class="n">test</span>
<span class="n">test2</span><span class="p">()</span>
File <span class="nb">"./mymodule.py"</span>, line <span class="m">3</span>, in <span class="n">test2</span>
<span class="nb">print</span> <span class="n">spam</span>
<span class="gr">NameError</span>: <span class="n">spam</span>
<span class="gp">>>> </span><span class="n">pdb</span><span class="o">.</span><span class="n">pm</span><span class="p">()</span>
<span class="go">> ./mymodule.py(3)test2()</span>
<span class="go">-> print spam</span>
<span class="go">(Pdb)</span>
</pre></div>
</div>
<p>The module defines the following functions; each enters the debugger in a
slightly different way:</p>
<dl class="function">
<dt id="pdb.run">
<code class="descclassname">pdb.</code><code class="descname">run</code><span class="sig-paren">(</span><em>statement</em><span class="optional">[</span>, <em>globals</em><span class="optional">[</span>, <em>locals</em><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pdb.run" title="Permalink to this definition">¶</a></dt>
<dd><p>Execute the <em>statement</em> (given as a string) under debugger control. The
debugger prompt appears before any code is executed; you can set breakpoints and
type <code class="docutils literal notranslate"><span class="pre">continue</span></code>, or you can step through the statement using <code class="docutils literal notranslate"><span class="pre">step</span></code> or
<code class="docutils literal notranslate"><span class="pre">next</span></code> (all these commands are explained below). The optional <em>globals</em> and
<em>locals</em> arguments specify the environment in which the code is executed; by
default the dictionary of the module <a class="reference internal" href="__main__.html#module-__main__" title="__main__: The environment where the top-level script is run."><code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code></a> is used. (See the
explanation of the <a class="reference internal" href="../reference/simple_stmts.html#exec"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">exec</span></code></a> statement or the <a class="reference internal" href="functions.html#eval" title="eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">eval()</span></code></a> built-in
function.)</p>
</dd></dl>
<dl class="function">
<dt id="pdb.runeval">
<code class="descclassname">pdb.</code><code class="descname">runeval</code><span class="sig-paren">(</span><em>expression</em><span class="optional">[</span>, <em>globals</em><span class="optional">[</span>, <em>locals</em><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pdb.runeval" title="Permalink to this definition">¶</a></dt>
<dd><p>Evaluate the <em>expression</em> (given as a string) under debugger control. When
<a class="reference internal" href="#pdb.runeval" title="pdb.runeval"><code class="xref py py-func docutils literal notranslate"><span class="pre">runeval()</span></code></a> returns, it returns the value of the expression. Otherwise this
function is similar to <a class="reference internal" href="#pdb.run" title="pdb.run"><code class="xref py py-func docutils literal notranslate"><span class="pre">run()</span></code></a>.</p>
</dd></dl>
<dl class="function">
<dt id="pdb.runcall">
<code class="descclassname">pdb.</code><code class="descname">runcall</code><span class="sig-paren">(</span><em>function</em><span class="optional">[</span>, <em>argument</em>, <em>...</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pdb.runcall" title="Permalink to this definition">¶</a></dt>
<dd><p>Call the <em>function</em> (a function or method object, not a string) with the given
arguments. When <a class="reference internal" href="#pdb.runcall" title="pdb.runcall"><code class="xref py py-func docutils literal notranslate"><span class="pre">runcall()</span></code></a> returns, it returns whatever the function call
returned. The debugger prompt appears as soon as the function is entered.</p>
</dd></dl>
<dl class="function">
<dt id="pdb.set_trace">
<code class="descclassname">pdb.</code><code class="descname">set_trace</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pdb.set_trace" title="Permalink to this definition">¶</a></dt>
<dd><p>Enter the debugger at the calling stack frame. This is useful to hard-code a
breakpoint at a given point in a program, even if the code is not otherwise
being debugged (e.g. when an assertion fails).</p>
</dd></dl>
<dl class="function">
<dt id="pdb.post_mortem">
<code class="descclassname">pdb.</code><code class="descname">post_mortem</code><span class="sig-paren">(</span><span class="optional">[</span><em>traceback</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pdb.post_mortem" title="Permalink to this definition">¶</a></dt>
<dd><p>Enter post-mortem debugging of the given <em>traceback</em> object. If no
<em>traceback</em> is given, it uses the one of the exception that is currently
being handled (an exception must be being handled if the default is to be
used).</p>
</dd></dl>
<dl class="function">
<dt id="pdb.pm">
<code class="descclassname">pdb.</code><code class="descname">pm</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pdb.pm" title="Permalink to this definition">¶</a></dt>
<dd><p>Enter post-mortem debugging of the traceback found in
<a class="reference internal" href="sys.html#sys.last_traceback" title="sys.last_traceback"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.last_traceback</span></code></a>.</p>
</dd></dl>
<p>The <code class="docutils literal notranslate"><span class="pre">run*</span></code> functions and <a class="reference internal" href="#pdb.set_trace" title="pdb.set_trace"><code class="xref py py-func docutils literal notranslate"><span class="pre">set_trace()</span></code></a> are aliases for instantiating the
<a class="reference internal" href="#pdb.Pdb" title="pdb.Pdb"><code class="xref py py-class docutils literal notranslate"><span class="pre">Pdb</span></code></a> class and calling the method of the same name. If you want to
access further features, you have to do this yourself:</p>
<dl class="class">
<dt id="pdb.Pdb">
<em class="property">class </em><code class="descclassname">pdb.</code><code class="descname">Pdb</code><span class="sig-paren">(</span><em>completekey='tab'</em>, <em>stdin=None</em>, <em>stdout=None</em>, <em>skip=None</em><span class="sig-paren">)</span><a class="headerlink" href="#pdb.Pdb" title="Permalink to this definition">¶</a></dt>
<dd><p><a class="reference internal" href="#pdb.Pdb" title="pdb.Pdb"><code class="xref py py-class docutils literal notranslate"><span class="pre">Pdb</span></code></a> is the debugger class.</p>
<p>The <em>completekey</em>, <em>stdin</em> and <em>stdout</em> arguments are passed to the
underlying <a class="reference internal" href="cmd.html#cmd.Cmd" title="cmd.Cmd"><code class="xref py py-class docutils literal notranslate"><span class="pre">cmd.Cmd</span></code></a> class; see the description there.</p>
<p>The <em>skip</em> argument, if given, must be an iterable of glob-style module name
patterns. The debugger will not step into frames that originate in a module
that matches one of these patterns. <a class="footnote-reference brackets" href="#id3" id="id1">1</a></p>
<p>Example call to enable tracing with <em>skip</em>:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">pdb</span><span class="p">;</span> <span class="n">pdb</span><span class="o">.</span><span class="n">Pdb</span><span class="p">(</span><span class="n">skip</span><span class="o">=</span><span class="p">[</span><span class="s1">'django.*'</span><span class="p">])</span><span class="o">.</span><span class="n">set_trace</span><span class="p">()</span>
</pre></div>
</div>
<div class="versionadded">
<p><span class="versionmodified added">New in version 2.7: </span>The <em>skip</em> argument.</p>
</div>
<dl class="method">
<dt id="pdb.Pdb.run">
<code class="descname">run</code><span class="sig-paren">(</span><em>statement</em><span class="optional">[</span>, <em>globals</em><span class="optional">[</span>, <em>locals</em><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pdb.Pdb.run" title="Permalink to this definition">¶</a></dt>
<dt id="pdb.Pdb.runeval">
<code class="descname">runeval</code><span class="sig-paren">(</span><em>expression</em><span class="optional">[</span>, <em>globals</em><span class="optional">[</span>, <em>locals</em><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pdb.Pdb.runeval" title="Permalink to this definition">¶</a></dt>
<dt id="pdb.Pdb.runcall">
<code class="descname">runcall</code><span class="sig-paren">(</span><em>function</em><span class="optional">[</span>, <em>argument</em>, <em>...</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pdb.Pdb.runcall" title="Permalink to this definition">¶</a></dt>
<dt id="pdb.Pdb.set_trace">
<code class="descname">set_trace</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pdb.Pdb.set_trace" title="Permalink to this definition">¶</a></dt>
<dd><p>See the documentation for the functions explained above.</p>
</dd></dl>
</dd></dl>
</div>
<div class="section" id="debugger-commands">
<span id="id2"></span><h1>26.3. Debugger Commands<a class="headerlink" href="#debugger-commands" title="Permalink to this headline">¶</a></h1>
<p>The debugger recognizes the following commands. Most commands can be
abbreviated to one or two letters; e.g. <code class="docutils literal notranslate"><span class="pre">h(elp)</span></code> means that either <code class="docutils literal notranslate"><span class="pre">h</span></code> or
<code class="docutils literal notranslate"><span class="pre">help</span></code> can be used to enter the help command (but not <code class="docutils literal notranslate"><span class="pre">he</span></code> or <code class="docutils literal notranslate"><span class="pre">hel</span></code>, nor
<code class="docutils literal notranslate"><span class="pre">H</span></code> or <code class="docutils literal notranslate"><span class="pre">Help</span></code> or <code class="docutils literal notranslate"><span class="pre">HELP</span></code>). Arguments to commands must be separated by
whitespace (spaces or tabs). Optional arguments are enclosed in square brackets
(<code class="docutils literal notranslate"><span class="pre">[]</span></code>) in the command syntax; the square brackets must not be typed.
Alternatives in the command syntax are separated by a vertical bar (<code class="docutils literal notranslate"><span class="pre">|</span></code>).</p>
<p>Entering a blank line repeats the last command entered. Exception: if the last
command was a <code class="docutils literal notranslate"><span class="pre">list</span></code> command, the next 11 lines are listed.</p>
<p>Commands that the debugger doesn’t recognize are assumed to be Python statements
and are executed in the context of the program being debugged. Python
statements can also be prefixed with an exclamation point (<code class="docutils literal notranslate"><span class="pre">!</span></code>). This is a
powerful way to inspect the program being debugged; it is even possible to
change a variable or call a function. When an exception occurs in such a
statement, the exception name is printed but the debugger’s state is not
changed.</p>
<p>Multiple commands may be entered on a single line, separated by <code class="docutils literal notranslate"><span class="pre">;;</span></code>. (A
single <code class="docutils literal notranslate"><span class="pre">;</span></code> is not used as it is the separator for multiple commands in a line
that is passed to the Python parser.) No intelligence is applied to separating
the commands; the input is split at the first <code class="docutils literal notranslate"><span class="pre">;;</span></code> pair, even if it is in the
middle of a quoted string.</p>
<p>The debugger supports aliases. Aliases can have parameters which allows one a
certain level of adaptability to the context under examination.</p>
<p id="index-2">If a file <code class="file docutils literal notranslate"><span class="pre">.pdbrc</span></code> exists in the user’s home directory or in the current
directory, it is read in and executed as if it had been typed at the debugger
prompt. This is particularly useful for aliases. If both files exist, the one
in the home directory is read first and aliases defined there can be overridden
by the local file.</p>
<dl>
<dt>h(elp) [<em>command</em>]</dt><dd><p>Without argument, print the list of available commands. With a <em>command</em> as
argument, print help about that command. <code class="docutils literal notranslate"><span class="pre">help</span> <span class="pre">pdb</span></code> displays the full
documentation file; if the environment variable <span class="target" id="index-3"></span><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PAGER</span></code> is defined, the
file is piped through that command instead. Since the <em>command</em> argument must
be an identifier, <code class="docutils literal notranslate"><span class="pre">help</span> <span class="pre">exec</span></code> must be entered to get help on the <code class="docutils literal notranslate"><span class="pre">!</span></code>
command.</p>
</dd>
<dt>w(here)</dt><dd><p>Print a stack trace, with the most recent frame at the bottom. An arrow
indicates the current frame, which determines the context of most commands.</p>
</dd>
<dt>d(own)</dt><dd><p>Move the current frame one level down in the stack trace (to a newer frame).</p>
</dd>
<dt>u(p)</dt><dd><p>Move the current frame one level up in the stack trace (to an older frame).</p>
</dd>
<dt>b(reak) [[<em>filename</em>:]<em>lineno</em> | <em>function</em>[, <em>condition</em>]]</dt><dd><p>With a <em>lineno</em> argument, set a break there in the current file. With a
<em>function</em> argument, set a break at the first executable statement within that
function. The line number may be prefixed with a filename and a colon, to
specify a breakpoint in another file (probably one that hasn’t been loaded yet).
The file is searched on <code class="docutils literal notranslate"><span class="pre">sys.path</span></code>. Note that each breakpoint is assigned a
number to which all the other breakpoint commands refer.</p>
<p>If a second argument is present, it is an expression which must evaluate to true
before the breakpoint is honored.</p>
<p>Without argument, list all breaks, including for each breakpoint, the number of
times that breakpoint has been hit, the current ignore count, and the associated
condition if any.</p>
</dd>
<dt>tbreak [[<em>filename</em>:]<em>lineno</em> | <em>function</em>[, <em>condition</em>]]</dt><dd><p>Temporary breakpoint, which is removed automatically when it is first hit. The
arguments are the same as break.</p>
</dd>
<dt>cl(ear) [<em>filename:lineno</em> | <em>bpnumber</em> [<em>bpnumber …</em>]]</dt><dd><p>With a <em>filename:lineno</em> argument, clear all the breakpoints at this line.
With a space separated list of breakpoint numbers, clear those breakpoints.
Without argument, clear all breaks (but first ask confirmation).</p>
</dd>
<dt>disable [<em>bpnumber</em> [<em>bpnumber …</em>]]</dt><dd><p>Disables the breakpoints given as a space separated list of breakpoint numbers.
Disabling a breakpoint means it cannot cause the program to stop execution, but
unlike clearing a breakpoint, it remains in the list of breakpoints and can be
(re-)enabled.</p>
</dd>
<dt>enable [<em>bpnumber</em> [<em>bpnumber …</em>]]</dt><dd><p>Enables the breakpoints specified.</p>
</dd>
<dt>ignore <em>bpnumber</em> [<em>count</em>]</dt><dd><p>Sets the ignore count for the given breakpoint number. If count is omitted, the
ignore count is set to 0. A breakpoint becomes active when the ignore count is
zero. When non-zero, the count is decremented each time the breakpoint is
reached and the breakpoint is not disabled and any associated condition
evaluates to true.</p>
</dd>
<dt>condition <em>bpnumber</em> [<em>condition</em>]</dt><dd><p>Condition is an expression which must evaluate to true before the breakpoint is
honored. If condition is absent, any existing condition is removed; i.e., the
breakpoint is made unconditional.</p>
</dd>
<dt>commands [<em>bpnumber</em>]</dt><dd><p>Specify a list of commands for breakpoint number <em>bpnumber</em>. The commands
themselves appear on the following lines. Type a line containing just ‘end’ to
terminate the commands. An example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="p">(</span><span class="n">Pdb</span><span class="p">)</span> <span class="n">commands</span> <span class="mi">1</span>
<span class="p">(</span><span class="n">com</span><span class="p">)</span> <span class="nb">print</span> <span class="n">some_variable</span>
<span class="p">(</span><span class="n">com</span><span class="p">)</span> <span class="n">end</span>
<span class="p">(</span><span class="n">Pdb</span><span class="p">)</span>
</pre></div>
</div>
<p>To remove all commands from a breakpoint, type commands and follow it
immediately with end; that is, give no commands.</p>
<p>With no <em>bpnumber</em> argument, commands refers to the last breakpoint set.</p>
<p>You can use breakpoint commands to start your program up again. Simply use the
continue command, or step, or any other command that resumes execution.</p>
<p>Specifying any command resuming execution (currently continue, step, next,
return, jump, quit and their abbreviations) terminates the command list (as if
that command was immediately followed by end). This is because any time you
resume execution (even with a simple next or step), you may encounter another
breakpoint—which could have its own command list, leading to ambiguities about
which list to execute.</p>
<p>If you use the ‘silent’ command in the command list, the usual message about
stopping at a breakpoint is not printed. This may be desirable for breakpoints
that are to print a specific message and then continue. If none of the other
commands print anything, you see no sign that the breakpoint was reached.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 2.5.</span></p>
</div>
</dd>
<dt>s(tep)</dt><dd><p>Execute the current line, stop at the first possible occasion (either in a
function that is called or on the next line in the current function).</p>
</dd>
<dt>n(ext)</dt><dd><p>Continue execution until the next line in the current function is reached or it
returns. (The difference between <code class="docutils literal notranslate"><span class="pre">next</span></code> and <code class="docutils literal notranslate"><span class="pre">step</span></code> is that <code class="docutils literal notranslate"><span class="pre">step</span></code> stops
inside a called function, while <code class="docutils literal notranslate"><span class="pre">next</span></code> executes called functions at (nearly)
full speed, only stopping at the next line in the current function.)</p>
</dd>
<dt>unt(il)</dt><dd><p>Continue execution until the line with the line number greater than the
current one is reached or when returning from current frame.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 2.6.</span></p>
</div>
</dd>
<dt>r(eturn)</dt><dd><p>Continue execution until the current function returns.</p>
</dd>
<dt>c(ont(inue))</dt><dd><p>Continue execution, only stop when a breakpoint is encountered.</p>
</dd>
<dt>j(ump) <em>lineno</em></dt><dd><p>Set the next line that will be executed. Only available in the bottom-most
frame. This lets you jump back and execute code again, or jump forward to skip
code that you don’t want to run.</p>
<p>It should be noted that not all jumps are allowed — for instance it is not
possible to jump into the middle of a <a class="reference internal" href="../reference/compound_stmts.html#for"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">for</span></code></a> loop or out of a
<a class="reference internal" href="../reference/compound_stmts.html#finally"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">finally</span></code></a> clause.</p>
</dd>
<dt>l(ist) [<em>first</em>[, <em>last</em>]]</dt><dd><p>List source code for the current file. Without arguments, list 11 lines around
the current line or continue the previous listing. With one argument, list 11
lines around at that line. With two arguments, list the given range; if the
second argument is less than the first, it is interpreted as a count.</p>
</dd>
<dt>a(rgs)</dt><dd><p>Print the argument list of the current function.</p>
</dd>
<dt>p <em>expression</em></dt><dd><p>Evaluate the <em>expression</em> in the current context and print its value.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p><code class="docutils literal notranslate"><span class="pre">print</span></code> can also be used, but is not a debugger command — this executes the
Python <a class="reference internal" href="../reference/simple_stmts.html#print"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">print</span></code></a> statement.</p>
</div>
</dd>
<dt>pp <em>expression</em></dt><dd><p>Like the <code class="docutils literal notranslate"><span class="pre">p</span></code> command, except the value of the expression is pretty-printed
using the <a class="reference internal" href="pprint.html#module-pprint" title="pprint: Data pretty printer."><code class="xref py py-mod docutils literal notranslate"><span class="pre">pprint</span></code></a> module.</p>
</dd>
<dt>alias [<em>name</em> [command]]</dt><dd><p>Creates an alias called <em>name</em> that executes <em>command</em>. The command must <em>not</em>
be enclosed in quotes. Replaceable parameters can be indicated by <code class="docutils literal notranslate"><span class="pre">%1</span></code>,
<code class="docutils literal notranslate"><span class="pre">%2</span></code>, and so on, while <code class="docutils literal notranslate"><span class="pre">%*</span></code> is replaced by all the parameters. If no
command is given, the current alias for <em>name</em> is shown. If no arguments are
given, all aliases are listed.</p>
<p>Aliases may be nested and can contain anything that can be legally typed at the
pdb prompt. Note that internal pdb commands <em>can</em> be overridden by aliases.
Such a command is then hidden until the alias is removed. Aliasing is
recursively applied to the first word of the command line; all other words in
the line are left alone.</p>
<p>As an example, here are two useful aliases (especially when placed in the
<code class="file docutils literal notranslate"><span class="pre">.pdbrc</span></code> file):</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="c1">#Print instance variables (usage "pi classInst")</span>
<span class="n">alias</span> <span class="n">pi</span> <span class="k">for</span> <span class="n">k</span> <span class="ow">in</span> <span class="o">%</span><span class="mf">1.</span><span class="vm">__dict__</span><span class="o">.</span><span class="n">keys</span><span class="p">():</span> <span class="nb">print</span> <span class="s2">"%1."</span><span class="p">,</span><span class="n">k</span><span class="p">,</span><span class="s2">"="</span><span class="p">,</span><span class="o">%</span><span class="mf">1.</span><span class="vm">__dict__</span><span class="p">[</span><span class="n">k</span><span class="p">]</span>
<span class="c1">#Print instance variables in self</span>
<span class="n">alias</span> <span class="n">ps</span> <span class="n">pi</span> <span class="bp">self</span>
</pre></div>
</div>
</dd>
<dt>unalias <em>name</em></dt><dd><p>Deletes the specified alias.</p>
</dd>
<dt>[!]<em>statement</em></dt><dd><p>Execute the (one-line) <em>statement</em> in the context of the current stack frame.
The exclamation point can be omitted unless the first word of the statement
resembles a debugger command. To set a global variable, you can prefix the
assignment command with a <code class="docutils literal notranslate"><span class="pre">global</span></code> command on the same line, e.g.:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="p">(</span><span class="n">Pdb</span><span class="p">)</span> <span class="k">global</span> <span class="n">list_options</span><span class="p">;</span> <span class="n">list_options</span> <span class="o">=</span> <span class="p">[</span><span class="s1">'-l'</span><span class="p">]</span>
<span class="p">(</span><span class="n">Pdb</span><span class="p">)</span>
</pre></div>
</div>
</dd>
<dt>run [<em>args</em> …]</dt><dd><p>Restart the debugged Python program. If an argument is supplied, it is split
with “shlex” and the result is used as the new sys.argv. History, breakpoints,
actions and debugger options are preserved. “restart” is an alias for “run”.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 2.6.</span></p>
</div>
</dd>
<dt>q(uit)</dt><dd><p>Quit from the debugger. The program being executed is aborted.</p>
</dd>
</dl>
<p class="rubric">Footnotes</p>
<dl class="footnote brackets">
<dt class="label" id="id3"><span class="brackets"><a class="fn-backref" href="#id1">1</a></span></dt>
<dd><p>Whether a frame is considered to originate in a certain module
is determined by the <code class="docutils literal notranslate"><span class="pre">__name__</span></code> in the frame globals.</p>
</dd>
</dl>
</div>
</div>
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<li><a class="reference internal" href="#">26.2. <code class="xref py py-mod docutils literal notranslate"><span class="pre">pdb</span></code> — The Python Debugger</a></li>
<li><a class="reference internal" href="#debugger-commands">26.3. Debugger Commands</a></li>
</ul>
<h4>Previous topic</h4>
<p class="topless"><a href="bdb.html"
title="previous chapter">26.1. <code class="xref py py-mod docutils literal notranslate"><span class="pre">bdb</span></code> — Debugger framework</a></p>
<h4>Next topic</h4>
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title="next chapter">26.4. The Python Profilers</a></p>
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