mingw/info/gdb/Completion.html

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  18
  19 <h3 class="section">Command completion</h3>
  20
  21    GDB can fill in the rest of a word in a command for you, if there is
  22 only one possibility; it can also show you what the valid possibilities
  23 are for the next word in a command, at any time.  This works for GDB
  24 commands, GDB subcommands, and the names of symbols in your program.
  25
  26    <p>Press the &lt;TAB&gt; key whenever you want GDB to fill out the rest
  27 of a word.  If there is only one possibility, GDB fills in the
  28 word, and waits for you to finish the command (or press &lt;RET&gt; to
  29 enter it).  For example, if you type
  30
  31 <pre class="example">     (gdb) info bre &lt;TAB&gt;
  32      </pre>
  33
  34 GDB fills in the rest of the word <code>breakpoints</code>, since that is
  35 the only <code>info</code> subcommand beginning with <code>bre</code>:
  36
  37 <pre class="example">     (gdb) info breakpoints
  38      </pre>
  39
  40 <p>You can either press &lt;RET&gt; at this point, to run the <code>info
  41 breakpoints</code> command, or backspace and enter something else, if
  42 <code>breakpoints</code> does not look like the command you expected.  (If you
  43 were sure you wanted <code>info breakpoints</code> in the first place, you
  44 might as well just type &lt;RET&gt; immediately after <code>info bre</code>,
  45 to exploit command abbreviations rather than command completion).
  46
  47    <p>If there is more than one possibility for the next word when you press
  48 &lt;TAB&gt;, GDB sounds a bell.  You can either supply more
  49 characters and try again, or just press &lt;TAB&gt; a second time;
  50 GDB displays all the possible completions for that word.  For
  51 example, you might want to set a breakpoint on a subroutine whose name
  52 begins with <code>make_</code>, but when you type <kbd>b make_&lt;TAB&gt;</kbd> GDB
  53 just sounds the bell.  Typing &lt;TAB&gt; again displays all the
  54 function names in your program that begin with those characters, for
  55 example:
  56
  57 <pre class="example">     (gdb) b make_ &lt;TAB&gt;
  58 <br>GDB sounds bell; press &lt;TAB&gt; again, to see:<br>
  59      make_a_section_from_file     make_environ
  60      make_abs_section             make_function_type
  61      make_blockvector             make_pointer_type
  62      make_cleanup                 make_reference_type
  63      make_command                 make_symbol_completion_list
  64      (gdb) b make_
  65      </pre>
  66
  67 <p>After displaying the available possibilities, GDB copies your
  68 partial input (<code>b make_</code> in the example) so you can finish the
  69 command.
  70
  71    <p>If you just want to see the list of alternatives in the first place, you
  72 can press <kbd>M-?</kbd> rather than pressing &lt;TAB&gt; twice.  <kbd>M-?</kbd>
  73 means <kbd>&lt;META&gt; ?</kbd>.  You can type this either by holding down a
  74 key designated as the &lt;META&gt; shift on your keyboard (if there is
  75 one) while typing <kbd>?</kbd>, or as &lt;ESC&gt; followed by <kbd>?</kbd>.
  76
  77    <p>Sometimes the string you need, while logically a "word", may contain
  78 parentheses or other characters that GDB normally excludes from
  79 its notion of a word.  To permit word completion to work in this
  80 situation, you may enclose words in <code>'</code> (single quote marks) in
  81 GDB commands.
  82
  83    <p>The most likely situation where you might need this is in typing the
  84 name of a C<tt>++</tt> function.  This is because C<tt>++</tt> allows function
  85 overloading (multiple definitions of the same function, distinguished
  86 by argument type).  For example, when you want to set a breakpoint you
  87 may need to distinguish whether you mean the version of <code>name</code>
  88 that takes an <code>int</code> parameter, <code>name(int)</code>, or the version
  89 that takes a <code>float</code> parameter, <code>name(float)</code>.  To use the
  90 word-completion facilities in this situation, type a single quote
  91 <code>'</code> at the beginning of the function name.  This alerts
  92 GDB that it may need to consider more information than usual
  93 when you press &lt;TAB&gt; or <kbd>M-?</kbd> to request word completion:
  94
  95 <pre class="example">     (gdb) b 'bubble( <kbd>M-?</kbd>
  96      bubble(double,double)    bubble(int,int)
  97      (gdb) b 'bubble(
  98      </pre>
  99
 100    <p>In some cases, GDB can tell that completing a name requires using
 101 quotes.  When this happens, GDB inserts the quote for you (while
 102 completing as much as it can) if you do not type the quote in the first
 103 place:
 104
 105 <pre class="example">     (gdb) b bub &lt;TAB&gt;
 106 <br>GDB alters your input line to the following, and rings a bell:<br>
 107      (gdb) b 'bubble(
 108      </pre>
 109
 110 <p>In general, GDB can tell that a quote is needed (and inserts it) if
 111 you have not yet started typing the argument list when you ask for
 112 completion on an overloaded symbol.
 113
 114    <p>For more information about overloaded functions, see <a href="C-plus-plus-expressions.html#C%20plus%20plus%20expressions">C<tt>++</tt> expressions</a>.  You can use the command <code>set
 115 overload-resolution off</code> to disable overload resolution;
 116 see <a href="Debugging-C-plus-plus.html#Debugging%20C%20plus%20plus">GDB features for C<tt>++</tt></a>.
 117
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