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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 ‘<samp><span class="samp">s</span></samp>’ is an alias |
| of the ‘<samp><span class="samp">step</span></samp>’ command even though it is otherwise an ambiguous |
| abbreviation of other commands like ‘<samp><span class="samp">set</span></samp>’ and ‘<samp><span class="samp">show</span></samp>’. |
| |
| <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 |
| ‘<samp><span class="samp">tty</span></samp>’ alias of the ‘<samp><span class="samp">set inferior-tty</span></samp>’ command. |
| |
| <p>You can define a new alias with the ‘<samp><span class="samp">alias</span></samp>’ 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 ‘<samp><span class="samp">-a</span></samp>’ option specifies that the new alias is an abbreviation |
| of the command. Abbreviations are not shown in command |
| lists displayed by the ‘<samp><span class="samp">help</span></samp>’ command. |
| |
| <p>The ‘<samp><span class="samp">--</span></samp>’ 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 ‘<samp><span class="samp">disas</span></samp>’, the current |
| shortest unambiguous abbreviation of the ‘<samp><span class="samp">disassemble</span></samp>’ command |
| and you wanted an even shorter version named ‘<samp><span class="samp">di</span></samp>’. |
| 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 ‘<samp><span class="samp">document</span></samp>’ command. |
| An alias automatically picks up the documentation of the existing command. |
| |
| <p>Here is an example where we make ‘<samp><span class="samp">elms</span></samp>’ an abbreviation of |
| ‘<samp><span class="samp">elements</span></samp>’ in the ‘<samp><span class="samp">set print elements</span></samp>’ 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 ‘<samp><span class="samp">set</span></samp>’ command, |
| and you want to have an alias for the corresponding ‘<samp><span class="samp">show</span></samp>’ |
| 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 ‘<samp><span class="samp">spe</span></samp>’ of the command ‘<samp><span class="samp">set print elements</span></samp>’. |
| |
| <pre class="smallexample"> (gdb) alias spe = set print elements |
| (gdb) spe 20 |
| </pre> |
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