CkPython

Check Whether an SSH Exit Status Was Received

Demonstrates the Chilkat Ssh.ChannelReceivedExitStatus method, which reports whether the server supplied an exit-status value for a channel. The only argument is the channel number. When it returns true, call GetChannelExitStatus to read the value.

Background: Always test this before reading the exit status, because the server is not required to send one for every channel type or command — treating a missing status as "0" would silently turn a failure into a success. Exit status is independent of EOF and CLOSE: it can arrive after EOF and either before or together with CLOSE.

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import sys
import chilkat

success = False

#  Demonstrates the Ssh.ChannelReceivedExitStatus method, which reports whether the server
#  supplied an exit-status value for a channel.  The only argument is the channel number.  When
#  it returns True, call GetChannelExitStatus to read the value.

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,"test -f /etc/hosts")
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)

success = ssh.ChannelReceiveToClose(channelNum)
if (success == False):
    print(ssh.lastErrorText())
    sys.exit()

#  The server is not required to send an exit status for every channel type or command.
if (ssh.ChannelReceivedExitStatus(channelNum)):
    exitStatus = ssh.GetChannelExitStatus(channelNum)
    print("Exit status: " + str(exitStatus))
else:
    print("The server did not provide an exit status.")

ssh.Disconnect()