Ruby

Get the Exit Status of a Remote SSH Command

Demonstrates the Chilkat Ssh.GetChannelExitStatus method, which returns the remote process exit status for a channel. The only argument is the channel number. Call it only after ChannelReceivedExitStatus returns true.

Background: The exit status is how you learn whether a remote command actually succeeded — recall that a successful exec request only means the request was accepted. By Unix convention 0 means success and any nonzero value indicates a failure. Retrieve it promptly after the receive operation and before calling unrelated SSH methods or releasing the channel, since the completed channel record can be discarded.

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Ruby

require 'chilkat'

success = false

#  Demonstrates the Ssh.GetChannelExitStatus method, which returns the remote process exit
#  status for a channel.  The only argument is the channel number.  Call it only after
#  ChannelReceivedExitStatus returns true.

ssh = Chilkat::CkSsh.new()

sshPort = 22
success = ssh.Connect("ssh.example.com",sshPort)
if (success == false)
    print ssh.lastErrorText() + "\n";
    exit
end

#  Normally you would not hard-code the password in source.  You should instead obtain it
#  from an interactive prompt, environment variable, or a secrets vault.
password = "mySshPassword"

success = ssh.AuthenticatePw("mySshLogin",password)
if (success == false)
    print ssh.lastErrorText() + "\n";
    exit
end

channelNum = ssh.OpenSessionChannel()
if (channelNum < 0)
    print ssh.lastErrorText() + "\n";
    exit
end

success = ssh.SendReqExec(channelNum,"grep -q root /etc/passwd")
if (success == false)
    print ssh.lastErrorText() + "\n";
    exit
end

#  IMPORTANT: Set a read timeout.  ReadTimeoutMs defaults to 0, which means no limit -- without
#  it, this call waits forever if the server never sends channel close.
ssh.put_ReadTimeoutMs(15000)

success = ssh.ChannelReceiveToClose(channelNum)
if (success == false)
    print ssh.lastErrorText() + "\n";
    exit
end

#  Retrieve the exit status immediately, before calling unrelated SSH methods or releasing the
#  channel, because the completed channel record can be discarded.
if (ssh.ChannelReceivedExitStatus(channelNum))
    exitStatus = ssh.GetChannelExitStatus(channelNum)
    print "Exit status: " + exitStatus.to_s() + "\n";

    #  By convention, 0 means the remote command succeeded.
    if (exitStatus == 0)
        print "The remote command succeeded." + "\n";
    else
        print "The remote command reported a failure." + "\n";
    end

end

ssh.Disconnect()