Home / server / Questions / 364645
In Process
Drew
Asked: 2012-02-29 12:20:58 +0800 CST

Multiple SSH sessions in a single command

  • 772

I'm trying to copy a database from one server to another. I tried using the following command and it's getting tied up on entering the ssh passwords. If I put in one server's password, it complains about the other and vice versa.

ssh root@server1 mysqldump --databases db | ssh root@server2 mysql

I managed to do the transfer by holding the dumps temporarily on my computer, just wondering if there is a way to get this to work.

mysql command-line-interface ssh shell

3 Answers

  1. Use ssh-keygen, copy the .ssh/ file that's generated to the other server, append the contents to the ./.ssh/authorized_keys file, then you can ssh into the other server without any password.

    • 5

  2. Using key authentication is definitely a valid way to go about it and what I'd probably do. If for some reason you can't do that, you can put a named pipe on the intermediate machine instead of storing the file there.

    mkfifo relaypipe
ssh root@server1 mysqldump --databases db > relaypipe #auth & send to background
ssh root@server2 mysql < relaypipe
    • 3

  3. If, for some reason, you can't use key authentication and require entering two passwords to complete this, you could use a FIFO:

    mkfifo myfifo

# In terminal session one, or a screen window, etc.
ssh root@server2 mysql < myfifo

# In terminal session two:
ssh root@server1 mysqldump --databases db > myfifo
    • 3