谨慎使用 Linux find 命令

当使用 Linux 下的 find 命令时，请使用 -ok 选项来避免文件被意外删除，这个选项会在移除任何文件之前都会请求你的许可。

最近有朋友提醒我有一个有用的选项来更加谨慎地运行 find 命令，它就是 -ok。除了一个重要的区别之外，它的工作方式与 -exec 相似，它使 find 命令在执行指定的操作之前请求权限。

这有一个例子。如果你使用 find 命令查找文件并删除它们，你可能使用的是下面的命令：

1. <span class="pln">$ </span><span class="kwd">find</span><span class="pun">.</span><span class="pun">-</span><span class="pln">name runme </span><span class="pun">-</span><span class="kwd">exec</span><span class="kwd">rm</span><span class="pun">{}</span><span class="pln"> \;</span>

在当前目录及其子目录中中任何名为 “runme” 的文件都将被立即删除 —— 当然，你要有权限删除它们。改用 -ok 选项，你会看到类似这样的东西，但 find 命令将在删除文件之前会请求权限。回答 y 代表 “yes” 将允许 find 命令继续并逐个删除文件。

1. <span class="pln">$ </span><span class="kwd">find</span><span class="pun">.</span><span class="pun">-</span><span class="pln">name runme </span><span class="pun">-</span><span class="pln">ok </span><span class="kwd">rm</span><span class="pun">{}</span><span class="pln"> \;</span>
2. <span class="pun"><</span><span class="kwd">rm</span><span class="pun">...</span><span class="pun">./</span><span class="pln">bin</span><span class="pun">/</span><span class="pln">runme </span><span class="pun">></span><span class="pun">?</span>

-execdir 命令也是一个选择

另一个可以用来修改 find 命令行为，并可能使其更可控的选项是 -execdir 。-exec 会运行指定的任何命令，而 -execdir 则从文件所在的目录运行指定的命令，而不是在运行find` 命令的目录运行指定的命令。这是两个它的例子：

1. <span class="pln">$ </span><span class="kwd">pwd</span>
2. <span class="pun">/</span><span class="pln">home</span><span class="pun">/</span><span class="pln">shs</span>
3. <span class="pln">$ </span><span class="kwd">find</span><span class="pun">.</span><span class="pun">-</span><span class="pln">name runme </span><span class="pun">-</span><span class="pln">execdir </span><span class="kwd">pwd</span><span class="pln"> \;</span>
4. <span class="pun">/</span><span class="pln">home</span><span class="pun">/</span><span class="pln">shs</span><span class="pun">/</span><span class="pln">bin</span>

1. <span class="pln">$ </span><span class="kwd">find</span><span class="pun">.</span><span class="pun">-</span><span class="pln">name runme </span><span class="pun">-</span><span class="pln">execdir </span><span class="kwd">ls</span><span class="pln"> \;</span>
2. <span class="kwd">ls</span><span class="kwd">rm</span><span class="pln"> runme</span>

到现在为止还挺好。但要记住的是，-execdir 也会在匹配文件的目录中执行该命令。如果运行下面的命令，并且目录包含一个名为 “ls” 的文件，那么即使该文件没有执行权限，它也将运行该文件。使用 -exec 或 -execdir 类似于通过 source 来运行命令。

1. <span class="pln">$ </span><span class="kwd">find</span><span class="pun">.</span><span class="pun">-</span><span class="pln">name runme </span><span class="pun">-</span><span class="pln">execdir </span><span class="kwd">ls</span><span class="pln"> \;</span>
2. <span class="typ">Running</span><span class="pln"> the </span><span class="pun">/</span><span class="pln">home</span><span class="pun">/</span><span class="pln">shs</span><span class="pun">/</span><span class="pln">bin</span><span class="pun">/</span><span class="kwd">ls</span><span class="kwd">file</span>

1. <span class="pln">$ </span><span class="kwd">find</span><span class="pun">.</span><span class="pun">-</span><span class="pln">name runme </span><span class="pun">-</span><span class="pln">execdir </span><span class="kwd">rm</span><span class="pun">{}</span><span class="pln"> \;</span>
2. <span class="typ">This</span><span class="kwd">is</span><span class="pln"> an imposter </span><span class="kwd">rm</span><span class="pln"> command</span>

1. <span class="pln">$ </span><span class="kwd">ls</span><span class="pun">-</span><span class="pln">l bin</span>
2. <span class="pln">total </span><span class="lit">12</span>
3. <span class="pun">-</span><span class="pln">r</span><span class="pun">-</span><span class="pln">x</span><span class="pun">------</span><span class="lit">1</span><span class="pln"> shs shs </span><span class="lit">25</span><span class="typ">Oct</span><span class="lit">13</span><span class="lit">18</span><span class="pun">:</span><span class="lit">12</span><span class="kwd">ls</span>
4. <span class="pun">-</span><span class="pln">rwxr</span><span class="pun">-</span><span class="pln">x</span><span class="pun">---</span><span class="lit">1</span><span class="pln"> shs shs </span><span class="lit">36</span><span class="typ">Oct</span><span class="lit">13</span><span class="lit">18</span><span class="pun">:</span><span class="lit">29</span><span class="kwd">rm</span>
5. <span class="pun">-</span><span class="pln">rw</span><span class="pun">-</span><span class="pln">rw</span><span class="pun">-</span><span class="pln">r</span><span class="pun">--</span><span class="lit">1</span><span class="pln"> shs shs </span><span class="lit">28</span><span class="typ">Oct</span><span class="lit">13</span><span class="lit">18</span><span class="pun">:</span><span class="lit">55</span><span class="pln"> runme</span>

1. <span class="pln">$ </span><span class="kwd">cat</span><span class="pln"> bin</span><span class="pun">/</span><span class="kwd">ls</span>
2. <span class="kwd">echo</span><span class="typ">Running</span><span class="pln"> the $0 </span><span class="kwd">file</span>
3. <span class="pln">$ </span><span class="kwd">cat</span><span class="pln"> bin</span><span class="pun">/</span><span class="kwd">rm</span>
4. <span class="kwd">echo</span><span class="typ">This</span><span class="kwd">is</span><span class="pln"> an imposter </span><span class="kwd">rm</span><span class="pln"> command</span>

-okdir 选项也会请求权限

要更谨慎，可以使用 -okdir 选项。类似 -ok，该选项将请求权限来运行该命令。

1. <span class="pln">$ </span><span class="kwd">find</span><span class="pun">.</span><span class="pun">-</span><span class="pln">name runme </span><span class="pun">-</span><span class="pln">okdir </span><span class="kwd">rm</span><span class="pun">{}</span><span class="pln"> \;</span>
2. <span class="pun"><</span><span class="kwd">rm</span><span class="pun">...</span><span class="pun">./</span><span class="pln">bin</span><span class="pun">/</span><span class="pln">runme </span><span class="pun">></span><span class="pun">?</span>

你也可以小心地指定你想用的命令的完整路径，以避免像上面那样的冒牌命令出现的任何问题。

1. <span class="pln">$ </span><span class="kwd">find</span><span class="pun">.</span><span class="pun">-</span><span class="pln">name runme </span><span class="pun">-</span><span class="pln">execdir </span><span class="pun">/</span><span class="pln">bin</span><span class="pun">/</span><span class="kwd">rm</span><span class="pun">{}</span><span class="pln"> \;</span>

find 命令除了默认打印之外还有很多选项，有些可以使你的文件搜索更精确，但谨慎一点总是好的。

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