Net::SCP implements the SCP (Secure CoPy) client protocol, allowing Ruby programs to securely and programmatically transfer individual files or entire directory trees to and from remote servers. It provides support for multiple simultaneous SCP copies working in parallel over the same connection, as well as for synchronous, serial copies.
Basic usage:
require 'net/scp'
Net::SCP.start("remote.host", "username", :password => "passwd") do |scp|
# synchronous (blocking) upload; call blocks until upload completes
scp.upload! "/local/path", "/remote/path"
# asynchronous upload; call returns immediately and requires SSH
# event loop to run
channel = scp.upload("/local/path", "/remote/path")
channel.wait
end
Net::SCP also provides an open-uri tie-in, so you can use the Kernel#open method to open and read a remote file:
# if you just want to parse SCP URL's:
require 'uri/scp'
url = URI.parse("scp://user@remote.host/path/to/file")
# if you want to read from a URL voa SCP:
require 'uri/open-scp'
puts open("scp://user@remote.host/path/to/file").read
Lastly, Net::SCP adds a method to the Net::SSH::Connection::Session class, allowing you to easily grab a Net::SCP reference from an existing Net::SSH session:
require 'net/ssh'
require 'net/scp'
Net::SSH.start("remote.host", "username", :password => "passwd") do |ssh|
ssh.scp.download! "/remote/path", "/local/path"
end
Progress Reporting
By default, uploading and downloading proceed silently, without any outward indication of their progress. For long running uploads or downloads (and especially in interactive environments) it is desirable to report to the user the progress of the current operation.
To receive progress reports for the current operation, just pass a block to upload or download (or one of their variants):
scp.upload!("/path/to/local", "/path/to/remote") do |ch, name, sent, total|
puts "#{name}: #{sent}/#{total}"
end
Whenever a new chunk of data is recieved for or sent to a file, the callback will be invoked, indicating the name of the file (local for downloads, remote for uploads), the number of bytes that have been sent or received so far for the file, and the size of the file.
Methods
Public Class
Public Instance
Classes and Modules
Public Class methods
Starts up a new SSH connection using the host and username parameters, instantiates a new SCP session on top of it, and then begins a download from remote to local. If the options hash includes an :ssh key, the value for that will be passed to the SSH connection as options (e.g., to set the password, etc.). All other options are passed to the download! method. If a block is given, it will be used to report progress (see "Progress Reporting", under Net::SCP).
# File lib/net/scp.rb, line 238 def self.download!(host, username, remote, local=nil, options={}, &progress) options = options.dup start(host, username, options.delete(:ssh) || {}) do |scp| return scp.download!(remote, local, options, &progress) end end
# File lib/net/scp.rb, line 251 def initialize(session) @session = session self.logger = session.logger end
Starts up a new SSH connection and instantiates a new SCP session on top of it. If a block is given, the SCP session is yielded, and the SSH session is closed automatically when the block terminates. If no block is given, the SCP session is returned.
# File lib/net/scp.rb, line 201 def self.start(host, username, options={}) session = Net::SSH.start(host, username, options) scp = new(session) if block_given? begin yield scp session.loop ensure session.close end else return scp end end
Starts up a new SSH connection using the host and username parameters, instantiates a new SCP session on top of it, and then begins an upload from local to remote. If the options hash includes an :ssh key, the value for that will be passed to the SSH connection as options (e.g., to set the password, etc.). All other options are passed to the upload! method. If a block is given, it will be used to report progress (see "Progress Reporting", under Net::SCP).
# File lib/net/scp.rb, line 224 def self.upload!(host, username, local, remote, options={}, &progress) options = options.dup start(host, username, options.delete(:ssh) || {}) do |scp| scp.upload!(local, remote, options, &progress) end end
Public Instance methods
Inititiate a synchronous (non-blocking) download from remote to local. The following options are recognized:
-
:recursive - the remote parameter refers to a remote directory, which should be downloaded to a new directory named local on the local machine.
-
:preserve - the atime and mtime of the file should be preserved.
-
:verbose - the process should result in verbose output on the server end (useful for debugging).
This method will return immediately, returning the Net::SSH::Connection::Channel object that will support the download. To wait for the download to finish, you can either call the wait method on the channel, or otherwise run the Net::SSH event loop until the channel's active? method returns false.
channel = scp.download("/remote/path", "/local/path")
channel.wait
# File lib/net/scp.rb, line 304 def download(remote, local, options={}, &progress) start_command(:download, local, remote, options, &progress) end
Same as download, but blocks until the download finishes. Identical to calling download and then calling the wait method on the channel object that is returned.
scp.download!("/remote/path", "/local/path")
If local is nil, and the download is not recursive (e.g., it is downloading only a single file), the file will be downloaded to an in-memory buffer and the resulting string returned.
data = download!("/remote/path")
# File lib/net/scp.rb, line 319 def download!(remote, local=nil, options={}, &progress) destination = local ? local : StringIO.new download(remote, destination, options, &progress).wait local ? true : destination.string end
Inititiate a synchronous (non-blocking) upload from local to remote. The following options are recognized:
-
:recursive - the local parameter refers to a local directory, which should be uploaded to a new directory named remote on the remote server.
-
:preserve - the atime and mtime of the file should be preserved.
-
:verbose - the process should result in verbose output on the server end (useful for debugging).
-
:chunk_size - the size of each "chunk" that should be sent. Defaults to 2048. Changing this value may improve throughput at the expense of decreasing interactivity.
This method will return immediately, returning the Net::SSH::Connection::Channel object that will support the upload. To wait for the upload to finish, you can either call the wait method on the channel, or otherwise run the Net::SSH event loop until the channel's active? method returns false.
channel = scp.upload("/local/path", "/remote/path")
channel.wait
# File lib/net/scp.rb, line 276 def upload(local, remote, options={}, &progress) start_command(:upload, local, remote, options, &progress) end
Same as upload, but blocks until the upload finishes. Identical to calling upload and then calling the wait method on the channel object that is returned. The return value is not defined.
# File lib/net/scp.rb, line 283 def upload!(local, remote, options={}, &progress) upload(local, remote, options, &progress).wait end