PureBasic

Using sudo in an SSH Shell Session

See more SSH Examples

Demonstrates how to run a command as sudo in a shell session. PureBasic

IncludeFile "CkStringBuilder.pb"
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.

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

    port.i = 22
    success = CkSsh::ckConnect(ssh,"the-ssh-server.com",port)
    If success <> 1
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    ; Authenticate using login/password:
    success = CkSsh::ckAuthenticatePw(ssh,"theSshLogin","theSshPassword")
    If success <> 1
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    ; Start a shell session.
    ; (The QuickShell method was added in Chilkat v9.5.0.65)
    channelNum.i = CkSsh::ckQuickShell(ssh)
    If channelNum < 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    ; Construct a StringBuilder with our command ("ls") run with "sudo"
    ; Note: The line-endings are potentially important.  Some SSH servers may
    ; require either LF or CRLF line endings.  (Unix/Linux/OSX servers typically
    ; use bare-LF line endings.  Windows servers likely use CRLF line endings.)

    ; Using "sudo -S" causes the sudo prompt to be written to stderr,
    ; and the password is read from stdin (i.e. from the echo command ouput).
    ; The sudo commands -p option allows us to set the prompt, and we can set it to
    ; the empty string, thus eliminating the prompt from the stderr completely.
    ; This allows us to run the command as root (super-user) with no prompt.
    sbCommands.i = CkStringBuilder::ckCreate()
    If sbCommands.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckAppend(sbCommands,"echo " + Chr(34) + "theSshPassword" + Chr(34) + " | sudo -S -p " + Chr(34) + Chr(34) + " ls" + Chr(10))

    ; Add another command to echo a marker string that
    ; we'll use in ChannelReceiveUntilMatch below.
    ; The use of single quotes around 'IS' is a trick so that the output
    ; of the command is "THIS IS THE END OF THE SCRIPT", but the terminal echo
    ; includes the single quotes.  This allows us to read until we see the actual
    ; output of the last command.
    CkStringBuilder::ckAppend(sbCommands,"echo THIS 'IS' THE END OF THE SCRIPT" + Chr(10))

    ; Send the commands..
    success = CkSsh::ckChannelSendString(ssh,channelNum,CkStringBuilder::ckGetAsString(sbCommands),"ansi")
    If success <> 1
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        CkStringBuilder::ckDispose(sbCommands)
        ProcedureReturn
    EndIf

    ; Send an EOF to indicate no more commands will be sent.
    ; For brevity, we're not checking the return values of each method call.
    ; Your code should check the success/failure of each call.
    success = CkSsh::ckChannelSendEof(ssh,channelNum)

    ; Receive output up to our marker.
    success = CkSsh::ckChannelReceiveUntilMatch(ssh,channelNum,"THIS IS THE END OF THE SCRIPT","ansi",1)

    ; Close the channel.
    ; It is important to close the channel only after receiving the desired output.
    success = CkSsh::ckChannelSendClose(ssh,channelNum)

    ; Get any remaining output..
    success = CkSsh::ckChannelReceiveToClose(ssh,channelNum)

    ; Get the complete output for all the commands in the session.
    Debug "--- output ----"
    Debug CkSsh::ckGetReceivedText(ssh,channelNum,"ansi")


    CkSsh::ckDispose(ssh)
    CkStringBuilder::ckDispose(sbCommands)


    ProcedureReturn
EndProcedure