当使用ssh将备份文件转储到另一台服务器上时，为什么会出现"tcgetattr"错误? [英] why is the `tcgetattr` error seen when ssh is used for dumping the backup file on another server?

问题描述

我想将表备份转储到另一台服务器上，并且正在使用ssh来完成. 当我运行以下命令时，出现错误，但转储文件已复制到目标位置.

I want to dump a tables backup on another server and I am using ssh for doing it. when I run the below command, it gives an error but dump file is copied to destination.

mysqldump -u username -ppassword dbname tablename | ssh -t -t servers_username@domain_name 'cat > /tmp/bckp.sql';

tcgetattr:无效的参数

tcgetattr: Invalid argument

如果按 CTRL + c ，则会在错误消息后附加Killed by signal 2.

If I press CTRL+c then it appends error message with Killed by signal 2.

为什么会出现此错误?

推荐答案

使用ssh -t -t或ssh -tt强制进行伪终端分配时，我已经看到此错误.

I've seen this error when forcing pseudo-terminal allocation using ssh -t -t or ssh -tt.

tcgetattr函数用于查找由文件描述符表示的伪终端的属性；它需要一个文件描述符和一个指向termios结构的指针来存储终端元数据.它从

The tcgetattr function is used to look up the attributes of the pseudoterminal represented by a file descriptor; it takes a file descriptor and a pointer to a termios structure to store the terminal metadata in. It looks to me from the stub code in glibc that this error represents a null pointer for the termios struct. I am not sure whether these same error handling semantics are in place for the platform-specific implementations of tcgetattr.

如果您想抑制此错误，请像下面这样调用ssh:

If you want to suppress this error, invoke ssh like so:

ssh 2>/dev/null

这会将STDERR重定向到/dev/null；使用此重定向调用时，您不会看到该错误.请注意，这将使用ssh掩盖其他错误；您可能需要出于调试目的将其删除.

This will redirect STDERR to /dev/null; you won't see the error when invoking with this redirection. Note that this will mask other errors with ssh; you may need to remove this for debugging purposes.

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