PureBasic

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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IncludeFile "CkSsh.pb"

Procedure ChilkatExample()

    success.i = 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.

    ssh.i = CkSsh::ckCreate()
    If ssh.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ;  The hostname may be a hostname or an IP address.
    hostname.s = "ssh.example.com"
    port.i = 22
    success = CkSsh::ckConnect(ssh,hostname,port)
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    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.
    password.s = "mySshPassword"

    success = CkSsh::ckAuthenticatePw(ssh,"mySshLogin",password)
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    ;  Open a session channel.  Several session channels may be open at once on one connection.
    channelNum.i = CkSsh::ckOpenSessionChannel(ssh)
    If channelNum < 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    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\""
    success = CkSsh::ckSendReqExec(ssh,channelNum,"ls -l /tmp")
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    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.
    CkSsh::setCkReadTimeoutMs(ssh, 15000)

    ;  Read the output until the server sends channel close, which happens when the command exits.
    success = CkSsh::ckChannelReceiveToClose(ssh,channelNum)
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    cmdOutput.s = CkSsh::ckGetReceivedText(ssh,channelNum,"utf-8")
    If CkSsh::ckLastMethodSuccess(ssh) = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    Debug cmdOutput

    ;  An accepted exec request does not mean the command succeeded.  Check the exit status.
    If CkSsh::ckChannelReceivedExitStatus(ssh,channelNum)
        Debug "Exit status: " + Str(CkSsh::ckGetChannelExitStatus(ssh,channelNum))
    EndIf

    CkSsh::ckDisconnect(ssh)


    CkSsh::ckDispose(ssh)


    ProcedureReturn
EndProcedure