linux bash shell的再次學習。

檔案描述符：

stdin，stdout 和 stderr 的檔案描述符分別是 0，1 和 2(一個檔案描述符說白了就是檔案系統為了跟蹤這個開啟的檔案而分配給它的一個數字）

參考：https://www.cnblogs.com/sparkdev/p/10247187.html

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Reopen STDOUT and STDERR after closing them?

I am running this on an Ubuntu machine, so I am not sure if it'll work for you, but this is what I did:

$ exec 1>&0 $ exec 2>&0

Suddenly, I had STDOUT and STDERR reconnected. Magic!

Explanation: Running the following commands, we get the following output:

$ ls -l /dev/stdout lrwxrwxrwx 1 root root 15 Jun 11 23:39 /dev/stdout -> /proc/self/fd/1 $ ls -l /proc/self/fd/1 lrwx------ 1 jay jay 64 Jun 22 01:34 /proc/self/fd/1 -> /dev/pts/10 $ ls -l /proc/self/fd/ total 0 lrwx------ 1 jay jay 64 Jun 22 01:35 0 -> /dev/pts/10 lrwx------ 1 jay jay 64 Jun 22 01:35 1 -> /dev/pts/10 lrwx------ 1 jay jay 64 Jun 22 01:35 2 -> /dev/pts/10 lr-x------ 1 jay jay 64 Jun 22 01:35 3 -> /proc/12224/fd
 

Since all three fd's point to the same thing, we can return them back to normal just by pointing to /dev/pts/10 which the exec 1>&0 and exec 2>&0 do