Lately there has been some talking in Ruby-Talk on how to send files using scp. Some people are doing just fine by calling scp with a pre-shared password, but I don’t like that approach and it doesn’t work for my purpose, so I did a bit of experimentation and found this code works:
require 'net/ssh' require 'net/sftp'
class SSHAgent def initialize @agent_env = Hash.new agenthandle = IO.popen("/usr/bin/ssh-agent -s", "r") agenthandle.each_line do |line| if line.index("echo") == nil line = line.slice(0..(line.index(';')-1)) key, value = line.chomp.split(/=/) puts "Key = #{key}, Value = #{value}" @agent_env[key] = value end end end def [](key) return @agent_env[key] end end
agent = SSHAgent.new ENV["SSH_AUTH_SOCK"] = agent["SSH_AUTH_SOCK"] ENV["SSH_AGENT_PID"] = agent["SSH_AGENT_PID"] system("/usr/bin/ssh-add")
Net::SSH.start( '192.168.1.12', :username=>'pgquiles', :compression_level=>0, :compression=>'none' ) do |session| session.sftp.connect do |sftp| sftp.put_file("bigvideo.avi", "bigvideo.avi") end end
I was using a passwordless private key for this experiment. Should you want to use a password-protected private key, you might want to set the DISPLAY and SSH_ASKPASS environment variables or use a smartcard reader and the ‘-s reader’ parameter.
The SSHAgent class comes from a public paste (I don’t know who its author is or the license that code is under).
Lastly, there is an undesired behaviour in Net::SFTP: when you use the put_file method it loads the whole file in memory, therefore you need loads of memory if you want to send big files. I’ve tried a naive fix (iterating writes) but it didn’t work (it complains about “no such file”, I think it’s a channels-related issue). Jamis Buck, the author of Net::SFTP, told me he currently has no time to fix this issue. In case you feel brave enough, the offending method starts in line 202 in
net-sftp-1.1.0/lib/net/sftp/session.rb.
I always spent my half an hour to read this website’s articles every day along with a cup of coffee.