如何检查/ dev / sdt的内容

我希望这不是一个大问题，但最终可能会成为一个很大的问题。

在某些情况下，我错误地在我的27英寸iMac上运行了以下命令：

sudo dd if=ubuntu-rescue.img of=/dev/sdt bs=1m

之后，它给了我以下输出：

233+1 records in
233+1 records out
244570112 bytes transferred in 2.275065 secs (107500277 bytes/sec)

问题是，我不想将ubuntu-rescue.img移​​到的位置/dev/sdt。kes！

我现在正在尝试弄清原始内容/dev/sdt/是什么（在我错误地将数据写入该文件之前），以及是否有一种方法可以检查内容（删除错误地复制到那里的磁盘映像，或者以某种方式）将内容/dev/sdt恢复为原始状态）。

另外，此dd命令会擦除之前存在的所有内容，还是仅向其中添加数据？

目前对我来说主要的问题是，我不知道是什么/dev/sdt（文件，驱动程序，已安装的驱动器？等），因此我无法知道如何检查所造成的损坏。因此，我需要了解运行此命令时正在查看的内容：

ls /dev

以及如何检查/访问/读取这些文件的内容。

我该怎么办？

For some further analysis, here are various output from various commands:

Not a directory:

    $ cd /dev/sdt
    -bash: cd: /dev/sdt: Not a directory

"Special Character" file

    $ file /dev/sdt
    /dev/sdt: character special

Verbose ls output:

    $ ls -l /dev/sdt
    crw-rw-rw-  1 root  wheel    0,   0 Dec 28 14:02 /dev/sdt

"Size of" `/dev/sdt`

    $ du -sk /dev/sdt
    0    /dev/sdt

I ran the same commands from update #1 on a new Mac Mini (that didn't have its `/dev/sdt` drive tampered with `dd`, and it gave me the **exact same** output as I got on the the iMac after I ran the erroneous `dd` command. Does this mean that the /dev/sdt didn't "record" the contents of the dd transfer? Because the "size" of /dev/sdt displays as zero when I run `$ ls -l /dev/sdt`. Could it be that I got lucky and didn't do any permanent damage?

Both of these commands: `$ du -sk /dev/sdt` and `$ ls -l /dev/sdt` give me the same results on the iMac (where the erroneous `dd` command was run) as it did on the untouched Mac Mini, showing that the data stored in `/dev/sdt` reads at 0 bytes. This makes me assume that this drive is a temporary system drive that is not meant to store data, because even after 240 MB of data was erroneously `dd`'d into it, it still reads at zero byes.

Lastly, I was given a good idea (by user frostschutz) to run this command:

    dd if=/dev/sdt of=mystery bs=1M count=234

And compare the results of the "mystery" file with the contents of the ubuntu-resuce.img, and the output from that experimental `dd` left me with a file called "mystery" which was exactly zero bytes. So I am starting to feel confident that I didn't do any lasting damage, and that this drive is always empty.

After listening to your very helpful discussions, and reading more on an [another (separate, but closely-related) question of mine here on U&L][1], I discovered that my question has already been asked, so for anyone wanting to read more on this discussion, you can look [here][2].

  [1]: https://unix.stackexchange.com/questions/176304/why-does-the-unix-system-need-so-many-0-byte-drives-at-dev?noredirect=1#comment291323_176304
  [2]: https://unix.stackexchange.com/questions/18239/understanding-dev-and-its-subdirs-and-files