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Hi I have a remote machine that has a mounted network drive.

I am trying to create a script that ask me for the name of folder I wish to copy, ssh into the remote machine and have it start the copy operation.

parallel/concurrent copy is needed as I have a time constraint.

here is what i have for now in my script in "perl" if it matters....

print `ssh -t -x rocup@factory "cp -rf $folder1/ /NFS; cp -rf $folder2/ /NFS; cp -rf $folder3/ /NFS"';

I also tried

print `ssh -t -x rocup@factory "cp -rf $folder1/ /NFS & cp -rf $folder2/ /NFS & cp -rf $folder3/ /NFS &"';

and 

print `ssh -t -x rocup@factory "nohup cp -rf $folder1/ /NFS;nohup cp -rf $folder2/ /NFS;nohup cp -rf $folder3/ /NFS"';

the above operations copy one by one and it takes over an hour to do it, Im hoping that I can trim down the time a bit by doing a concurrent copy

the host factory does not have private/public key setup, so i cannot do a

ssh -f -t -x rocup@factory "cp -rf $folder1/ /NFS"; as I would need to enter password 3 times.

Thanks for helping

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    Are you sure a parallel copy will be faster? – Amok Aug 24 '09 at 19:54
  • I am not sure, I just want to try it out. When I am using filezilla (which has built in concurrent transfer) it did made the file transfer faster –  Aug 24 '09 at 19:58

1 Answers1

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If you can set up private/public key to sign into your local box from the remote machine, you can do this with two scripts.

First script, located on your box is what you run and takes as input the folders you want to copy. It does several things:

  1. Output a second script with copy commands:

    cp -rf $folder1/ /NFS &
    cp -rf $folder2/ /NFS &
    cp -rf $folder3/ /NFS &

  2. chmod the generated script 755

  3. ssh into the remote machine with this command:

    ssh rocup@factory "scp yourmachine:/path/to/generated/script ./ && ./script"

That last command requires that your user on the remote machine has a private key without a passphrase to scp back into where your generated script was created. There are ways around using a passphraseless key (forwarding agents) but this quick and dirty way can at least form a proof of concept as to whether the concurrent copy saves any time.

Ryan Ahearn
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  • my *guess* is that it won't be any faster than sequential copy (drive heads moving a lot and such), but I suppose it *could* be. – warren Mar 17 '10 at 15:18