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<h3 class="section">23.6 Creating new spellings of existing commands</h3>

<p><a name="index-aliases-for-commands-2890"></a>
It is often useful to define alternate spellings of existing commands. 
For example, if a new <span class="sc">gdb</span> command defined in Python has
a long name to type, it is handy to have an abbreviated version of it
that involves less typing.

   <p><span class="sc">gdb</span> itself uses aliases.  For example &lsquo;<samp><span class="samp">s</span></samp>&rsquo; is an alias
of the &lsquo;<samp><span class="samp">step</span></samp>&rsquo; command even though it is otherwise an ambiguous
abbreviation of other commands like &lsquo;<samp><span class="samp">set</span></samp>&rsquo; and &lsquo;<samp><span class="samp">show</span></samp>&rsquo;.

   <p>Aliases are also used to provide shortened or more common versions
of multi-word commands.  For example, <span class="sc">gdb</span> provides the
&lsquo;<samp><span class="samp">tty</span></samp>&rsquo; alias of the &lsquo;<samp><span class="samp">set inferior-tty</span></samp>&rsquo; command.

   <p>You can define a new alias with the &lsquo;<samp><span class="samp">alias</span></samp>&rsquo; command.

     
<a name="index-alias-2891"></a>
<dl><dt><code>alias [-a] [--] </code><var>ALIAS</var><code> = </code><var>COMMAND</var><dd>
</dl>

   <p><var>ALIAS</var> specifies the name of the new alias. 
Each word of <var>ALIAS</var> must consist of letters, numbers, dashes and
underscores.

   <p><var>COMMAND</var> specifies the name of an existing command
that is being aliased.

   <p>The &lsquo;<samp><span class="samp">-a</span></samp>&rsquo; option specifies that the new alias is an abbreviation
of the command.  Abbreviations are not shown in command
lists displayed by the &lsquo;<samp><span class="samp">help</span></samp>&rsquo; command.

   <p>The &lsquo;<samp><span class="samp">--</span></samp>&rsquo; option specifies the end of options,
and is useful when <var>ALIAS</var> begins with a dash.

   <p>Here is a simple example showing how to make an abbreviation
of a command so that there is less to type. 
Suppose you were tired of typing &lsquo;<samp><span class="samp">disas</span></samp>&rsquo;, the current
shortest unambiguous abbreviation of the &lsquo;<samp><span class="samp">disassemble</span></samp>&rsquo; command
and you wanted an even shorter version named &lsquo;<samp><span class="samp">di</span></samp>&rsquo;. 
The following will accomplish this.

<pre class="smallexample">     (gdb) alias -a di = disas
</pre>
   <p>Note that aliases are different from user-defined commands. 
With a user-defined command, you also need to write documentation
for it with the &lsquo;<samp><span class="samp">document</span></samp>&rsquo; command. 
An alias automatically picks up the documentation of the existing command.

   <p>Here is an example where we make &lsquo;<samp><span class="samp">elms</span></samp>&rsquo; an abbreviation of
&lsquo;<samp><span class="samp">elements</span></samp>&rsquo; in the &lsquo;<samp><span class="samp">set print elements</span></samp>&rsquo; command. 
This is to show that you can make an abbreviation of any part
of a command.

<pre class="smallexample">     (gdb) alias -a set print elms = set print elements
     (gdb) alias -a show print elms = show print elements
     (gdb) set p elms 20
     (gdb) show p elms
     Limit on string chars or array elements to print is 200.
</pre>
   <p>Note that if you are defining an alias of a &lsquo;<samp><span class="samp">set</span></samp>&rsquo; command,
and you want to have an alias for the corresponding &lsquo;<samp><span class="samp">show</span></samp>&rsquo;
command, then you need to define the latter separately.

   <p>Unambiguously abbreviated commands are allowed in <var>COMMAND</var> and
<var>ALIAS</var>, just as they are normally.

<pre class="smallexample">     (gdb) alias -a set pr elms = set p ele
</pre>
   <p>Finally, here is an example showing the creation of a one word
alias for a more complex command. 
This creates alias &lsquo;<samp><span class="samp">spe</span></samp>&rsquo; of the command &lsquo;<samp><span class="samp">set print elements</span></samp>&rsquo;.

<pre class="smallexample">     (gdb) alias spe = set print elements
     (gdb) spe 20
</pre>
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