Visual FoxPro

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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LOCAL lnSuccess
LOCAL loSsh
LOCAL lcHostname
LOCAL lnPort
LOCAL lcPassword
LOCAL lnChannelNum
LOCAL lcCmdOutput

lnSuccess = 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.

loSsh = CreateObject('Chilkat.Ssh')

*  The hostname may be a hostname or an IP address.
lcHostname = "ssh.example.com"
lnPort = 22
lnSuccess = loSsh.Connect(lcHostname,lnPort)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
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.
lcPassword = "mySshPassword"

lnSuccess = loSsh.AuthenticatePw("mySshLogin",lcPassword)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

*  Open a session channel.  Several session channels may be open at once on one connection.
lnChannelNum = loSsh.OpenSessionChannel()
IF (lnChannelNum < 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
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\""
lnSuccess = loSsh.SendReqExec(lnChannelNum,"ls -l /tmp")
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
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.
loSsh.ReadTimeoutMs = 15000

*  Read the output until the server sends channel close, which happens when the command exits.
lnSuccess = loSsh.ChannelReceiveToClose(lnChannelNum)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

lcCmdOutput = loSsh.GetReceivedText(lnChannelNum,"utf-8")
IF (loSsh.LastMethodSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

? lcCmdOutput

*  An accepted exec request does not mean the command succeeded.  Check the exit status.
IF (loSsh.ChannelReceivedExitStatus(lnChannelNum)) THEN
    ? "Exit status: " + STR(loSsh.GetChannelExitStatus(lnChannelNum))
ENDIF

loSsh.Disconnect()

RELEASE loSsh