Ruby

SSH Exec (Execute Command Line)

Demonstrates running a single command on an SSH server with an exec request and retrieving its output. The example connects, authenticates, opens a session channel, sends the command, reads until the server closes the channel, and then checks the exit status.

Background: exec is the workhorse of SSH automation: it runs one command and the server closes the channel when the command exits, which is a definitive end-of-output signal. No PTY is involved, so the shell runs non-interactively — no prompt, no echoed input, no ANSI escape codes — giving clean, parseable output. Remember that an accepted exec request only means the request was accepted; the command's own success is reported through the channel exit status. Command syntax depends on the remote shell, which is the user's default shell on Linux/UNIX and usually CMD.EXE on Windows SSH servers.

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Ruby

require 'chilkat'

success = false

#  This example requires the Chilkat API to have been previously unlocked.
#  See Global Unlock Sample for sample code.

#  Demonstrates running a single command on an SSH server with an exec request and retrieving
#  its output.  An exec request runs one command and the server closes the channel when it
#  finishes -- no PTY and no shell prompt are involved, so the output is clean and parseable.

ssh = Chilkat::CkSsh.new()

#  The hostname may be a hostname or an IP address.
hostname = "ssh.example.com"
port = 22
success = ssh.Connect(hostname,port)
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

#  Open a session channel.  Several session channels may be open at once on one connection.
channelNum = ssh.OpenSessionChannel()
if (channelNum < 0)
    print ssh.lastErrorText() + "\n";
    exit
end

#  The command syntax depends on the remote system's shell.  On Linux/UNIX it is typically the
#  user's default shell; on Windows SSH servers it is usually CMD.EXE.
#    Linux/UNIX:  "ls -l /tmp"        or  "cd /etc; ls -la"
#    Windows:     "dir"               or  "\"cd \\temp&&dir\""
success = ssh.SendReqExec(channelNum,"ls -l /tmp")
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)

#  Read the output until the server sends channel close, which happens when the command exits.
success = ssh.ChannelReceiveToClose(channelNum)
if (success == false)
    print ssh.lastErrorText() + "\n";
    exit
end

cmdOutput = ssh.getReceivedText(channelNum,"utf-8")
if (ssh.get_LastMethodSuccess() == false)
    print ssh.lastErrorText() + "\n";
    exit
end

print cmdOutput + "\n";

#  An accepted exec request does not mean the command succeeded.  Check the exit status.
if (ssh.ChannelReceivedExitStatus(channelNum))
    print "Exit status: " + ssh.GetChannelExitStatus(channelNum).to_s() + "\n";
end

ssh.Disconnect()