CkPython

Send EOF on an SSH Channel

Demonstrates the Chilkat Ssh.ChannelSendEof method, which sends an SSH EOF message on a channel. The only argument is the channel number. EOF closes only the client-to-server direction; the application may still receive stdout, stderr, exit status, EOF, and CLOSE from the server.

Background: Many remote commands read standard input until it ends — wc, sort, cat and friends. Sending EOF is the SSH equivalent of pressing Ctrl+D: it tells the remote process no more input is coming so it can finish and emit results. After sending EOF, do not send more data on that channel; a later send may return true even though nothing is delivered.

Chilkat CkPython Downloads

Download Chilkat for CkPython

CkPython

import sys
import chilkat

success = False

#  Demonstrates the Ssh.ChannelSendEof method, which sends an SSH EOF message on a channel.  The
#  only argument is the channel number.  EOF closes only the client-to-server direction; output
#  may still be received from the server.

ssh = chilkat.CkSsh()

sshPort = 22
success = ssh.Connect("ssh.example.com",sshPort)
if (success == False):
    print(ssh.lastErrorText())
    sys.exit()

#  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())
    sys.exit()

channelNum = ssh.OpenSessionChannel()
if (channelNum < 0):
    print(ssh.lastErrorText())
    sys.exit()

success = ssh.SendReqExec(channelNum,"wc -l")
if (success == False):
    print(ssh.lastErrorText())
    sys.exit()

#  Send input to the remote command.
success = ssh.ChannelSendString(channelNum,"line one\nline two\nline three\n","utf-8")
if (success == False):
    print(ssh.lastErrorText())
    sys.exit()

#  Signal that no more input will be sent.  Do not send more data on this channel afterward.
success = ssh.ChannelSendEof(channelNum)
if (success == False):
    print(ssh.lastErrorText())
    sys.exit()

#  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)

#  Output can still be received after EOF is sent.
success = ssh.ChannelReceiveToClose(channelNum)
if (success == False):
    print(ssh.lastErrorText())
    sys.exit()

output = ssh.getReceivedText(channelNum,"utf-8")
if (ssh.get_LastMethodSuccess() == False):
    print(ssh.lastErrorText())
    sys.exit()

print(output)

ssh.Disconnect()