Re: Using pre-existing SSH connection

[Joe Sapp]

On Mon, May 8, 2017 at 4:09 PM, Ole Tange <ole@tange.dk> wrote:
> On Mon, May 8, 2017 at 9:02 PM, Joe Sapp <sappj@ieee.org> wrote:
>
>> It appears that Parallel creates a new SSH connection when it runs,
>> even if an existing connection is open and ControlMaster is enabled in
>> ~/.ssh/config and Parallel config (I'm not sure how to test this,
>> though).  I would like to open an SSH connection at the beginning of
>> my session and use that one for subsequent connections to the same
>> machine.  Is there a way to tell Parallel to use an existing SSH
>> connection, if there is one open?  Maybe by specifying the control
>> path?
>
> Check out `man parallel`:
>
>       --controlmaster
>       -M       Use ssh's ControlMaster to make ssh connections
>                faster. Useful if jobs run remote and are very
>                fast to run. This is disabled for sshlogins
>                that specify their own ssh command.
>

I am using --controlmaster in my calls to parallel, but it seems to
still be making new connections even though I don't have a custom ssh
command.  I will try to come up with a test case and some evidence.

-- 
Joe