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Set an Environment Variable on an SSH Channel

Demonstrates the Chilkat Ssh.SendReqSetEnv method, which asks the server to set an environment variable for a session channel. The arguments are the channel number, the variable name, and its value. Send these requests before the exec, shell, or subsystem request.

Background: This is the clean way to pass configuration to a remote command without embedding it in the command line. Be aware that many SSH servers restrict which variables clients may set (OpenSSH's AcceptEnv), so a request can be silently ignored or rejected — do not rely on it without verifying the server's policy.

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Local $bSuccess = False

;  Demonstrates the Ssh.SendReqSetEnv method, which asks the server to set an environment
;  variable for a session channel.  The 1st argument is the channel number, the 2nd is the
;  variable name, and the 3rd is its value.  Send it before the exec, shell, or subsystem
;  request.

$oSsh = ObjCreate("Chilkat.Ssh")

Local $iSshPort = 22
$bSuccess = $oSsh.Connect("ssh.example.com",$iSshPort)
If ($bSuccess = False) Then
    ConsoleWrite($oSsh.LastErrorText & @CRLF)
    Exit
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.
Local $sPassword = "mySshPassword"

$bSuccess = $oSsh.AuthenticatePw("mySshLogin",$sPassword)
If ($bSuccess = False) Then
    ConsoleWrite($oSsh.LastErrorText & @CRLF)
    Exit
EndIf

;  Open a session channel.  A negative return value indicates failure.
Local $iChannelNum = $oSsh.OpenSessionChannel()
If ($iChannelNum < 0) Then
    ConsoleWrite($oSsh.LastErrorText & @CRLF)
    Exit
EndIf

;  Set environment variables for the channel.  Multiple variables may be requested.
$bSuccess = $oSsh.SendReqSetEnv($iChannelNum,"LANG","en_US.UTF-8")
If ($bSuccess = False) Then
    ConsoleWrite($oSsh.LastErrorText & @CRLF)
    Exit
EndIf

$bSuccess = $oSsh.SendReqSetEnv($iChannelNum,"MY_APP_MODE","production")
If ($bSuccess = False) Then
    ConsoleWrite($oSsh.LastErrorText & @CRLF)
    Exit
EndIf

;  Now run the command, which sees the requested environment.
$bSuccess = $oSsh.SendReqExec($iChannelNum,"echo $MY_APP_MODE")
If ($bSuccess = False) Then
    ConsoleWrite($oSsh.LastErrorText & @CRLF)
    Exit
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

$bSuccess = $oSsh.ChannelReceiveToClose($iChannelNum)
If ($bSuccess = False) Then
    ConsoleWrite($oSsh.LastErrorText & @CRLF)
    Exit
EndIf

Local $sOutput = $oSsh.GetReceivedText($iChannelNum,"utf-8")
If ($oSsh.LastMethodSuccess = False) Then
    ConsoleWrite($oSsh.LastErrorText & @CRLF)
    Exit
EndIf

ConsoleWrite($sOutput & @CRLF)

$oSsh.Disconnect