Data Transfer Tools: rsync, scp, sftp
This article tells you about some of the basic transfer tools available for use with JASMIN that work over an SSH connection:
- rsync (over SSH)
rsync over SSH
$ rsync mydata user@remote-host:/data/
will use SSH to connect as
remote-host. Once connected, it will invoke another copy of rsync on the remote host, and then the two programmes will talk to each other over the connection, working together to determine which parts of
mydata are already on the remote host and don't need to be transferred over the connection.
The generic syntax is:
$ rsync [OPTION] ... SRC [SRC] ... [USER@]HOST:DEST $ rsync [OPTION] ... [USER@]HOST:SRC [DEST]
...where SRC is the file or directory (or a list of multiple files and directories) to copy from, and DEST represents the file or directory to copy to. (Square brackets indicate optional parameters.)
For more information visit the official rsync website.
rsync example on JASMIN
Here is a simple example using rsync over SSH to copy a file to a Group Workspace on JASMIN:
$ exec ssh-agent $SHELL $ ssh-add ~/.ssh/id_rsa_jasmin # or other key filename as needed $ rsync myfile <username>@jasmin-xfer1.ceda.ac.uk:/group_workspaces/jasmin/myproject/data/
NOTE: The first two lines are the standard method for setting up the SSH agent in order to allow connections without prompting for a passphrase each time.
scp is another basic command-line tool for secure copying between two machines. It is installed as part of most SSH implementations and comes as standard on the JASMIN transfer servers.
scp is the secure analogue of the
rcp command. Typically, the syntax of
scp is like the syntax of
To copy a file to a host:
$ scp myfile user@host:directory/target
To copy a file (or directory) from a host to the local system:
$ scp user@host:directory/source target $ scp -r user@host:directory/source_folder target_folder
Note that if the remote host uses a port other than the default of 22, it can be specified in the command. For example, copying a file from host over a non-standard SSH port (2222):
$ scp -P 2222 user@host:directory/source target
For more information on scp please visit the following website.
sftp is a similar tool to scp, but the underlying SFTP protocol allows for a range of operations on remote files which make it more like a remote file system protocol. sftp includes extra capabilities such as resuming interrupted transfers, directory listings, and remote file removal.
For basic transfer of a file on JASMIN to the local machine:
$ sftp email@example.com:/group_workspaces/jasmin/myproject/data/notes.txt ./
For more information see the Wikipedia page on SFTP.
Note on performance
While convenient and familiar to many users, the tools described above do not make efficient use of available bandwidth for transferring large quantities of data via high-speed networks over long distances. Please consult [INSERT LINK] to learn more about which might be the most appropriate tool to use in different contexts.