Xbase++

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.

Chilkat Xbase++ Downloads

Download Chilkat for Xbase++

Xbase++

LOCAL nSuccess
LOCAL oSsh
LOCAL cHostname
LOCAL nPort
LOCAL cPassword
LOCAL nChannelNum
LOCAL cCmdOutput

nSuccess := 0

//  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.

oSsh := CreateObject("Chilkat.Ssh")

//  The hostname may be a hostname or an IP address.
cHostname := "ssh.example.com"
nPort := 22
nSuccess := oSsh:Connect(cHostname, nPort)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  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.
cPassword := "mySshPassword"

nSuccess := oSsh:AuthenticatePw("mySshLogin", cPassword)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  Open a session channel.  Several session channels may be open at once on one connection.
nChannelNum := oSsh:OpenSessionChannel()
IF (nChannelNum < 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  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\""
nSuccess := oSsh:SendReqExec(nChannelNum, "ls -l /tmp")
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  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.
oSsh:ReadTimeoutMs := 15000

//  Read the output until the server sends channel close, which happens when the command exits.
nSuccess := oSsh:ChannelReceiveToClose(nChannelNum)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

cCmdOutput := oSsh:GetReceivedText(nChannelNum, "utf-8")
IF (oSsh:LastMethodSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

? cCmdOutput

//  An accepted exec request does not mean the command succeeded.  Check the exit status.
IF (oSsh:ChannelReceivedExitStatus(nChannelNum))
    ? "Exit status: " + Str(oSsh:GetChannelExitStatus(nChannelNum))
ENDIF

oSsh:Disconnect()

oSsh:destroy()