Create a persistent connection to a machine

ssh -MNf <user>@<host>
Create a persistent SSH connection to the host in the background. Combine this with settings in your ~/.ssh/config: Host host ControlPath ~/.ssh/master-%r@%h:%p ControlMaster no All the SSH connections to the machine will then go through the persisten SSH socket. This is very useful if you are using SSH to synchronize files (using rsync/sftp/cvs/svn) on a regular basis because it won't create a new socket each time to open an ssh connection.

By: raphink
2009-02-26 14:11:19

What Others Think

I had tried this before running a command on one SSH and backgrounding it (ssh user@host "command" &), but this is much nicer. You can also set the options on the command line if you only want the control process for a single job: ssh -o "ControlPath ~/.ssh/master-%r_%h_%p" -MNf scp -o "ControlMaster no" -o "ControlPath ~/.ssh/master-%r_%h_%p" user@host:file . (ControlMaster no is default, so that option probably isn't necessary for the scp, but its included here for completeness)
sud0er · 665 weeks and 2 days ago
Yes, ControlMaster no is default indeed. It can be useful in other cases to use auto instead, if you don't care to have a socket always open, but you might have several SSH connections following one another. In that case, you don't need the "ssh -MNf" command, and the first SSH command to be launched will create the socket which will be used by the following commands.
raphink · 665 weeks and 2 days ago
I use: ssh -MNTf <user>@<host> Which adds the '-T' option to disable pseudo-tty allocation, which lowers the memory used on the remote machine. Also note that the -N option is only for protocol 2
AskApache · 505 weeks and 2 days ago
Cool, but when you need to maximize network speed, using a single TCP connection is not the best for file transfer.
colemar · 371 weeks and 1 day ago
seofox · 1 week and 1 day ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

You must be signed in to comment.

What's this? is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

Share Your Commands

Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.


Subscribe to the feeds.

Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

Subscribe to the feed for: