PowerBuilder

Collect Completed SSH Commands with QuickCmdCheck

Demonstrates the Chilkat Ssh.QuickCmdCheck method, which waits for any command started by QuickCmdSend to complete. The only argument is the poll timeout in milliseconds; 0 performs a nonblocking check. It returns the channel number of a completed command, -1 when commands are still pending but none finished before the timeout, or -2 when no quick commands remain or an error occurred.

Background: This is the collection half of the concurrent pattern. Each completed channel is reported only once, so looping until -2 drains every outstanding command exactly once. Distinguish the two negative values carefully: -1 simply means "still working, ask again," while -2 means there is nothing left to wait for — or that the connection failed, so check LastErrorText when the distinction matters. Manually opened exec channels are not reported here.

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integer li_rc
integer li_Success
oleobject loo_Ssh
integer li_SshPort
string ls_Password
integer li_Channel1
integer li_Channel2
integer li_PollTimeoutMs
integer li_CompletedChannel
string ls_Output

li_Success = 0

//  Demonstrates the Ssh.QuickCmdCheck method, which waits for any command started by
//  QuickCmdSend to complete.  The only argument is the poll timeout in milliseconds; 0 performs
//  a nonblocking check.

loo_Ssh = create oleobject
li_rc = loo_Ssh.ConnectToNewObject("Chilkat.Ssh")
if li_rc < 0 then
    destroy loo_Ssh
    MessageBox("Error","Connecting to COM object failed")
    return
end if

li_SshPort = 22
li_Success = loo_Ssh.Connect("ssh.example.com",li_SshPort)
if li_Success = 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

//  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.
ls_Password = "mySshPassword"

li_Success = loo_Ssh.AuthenticatePw("mySshLogin",ls_Password)
if li_Success = 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

//  Start two commands that will finish at different times.
li_Channel1 = loo_Ssh.QuickCmdSend("sleep 2; echo first done")
if li_Channel1 < 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

li_Channel2 = loo_Ssh.QuickCmdSend("echo second done")
if li_Channel2 < 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

//  Collect the results as they complete.  The return value is the channel number of a completed
//  command, -1 if commands are still pending but none finished before the timeout, or -2 when
//  no quick commands remain (or an error occurred).
li_PollTimeoutMs = 5000
li_CompletedChannel = loo_Ssh.QuickCmdCheck(li_PollTimeoutMs)
do while li_CompletedChannel <> -2
    if li_CompletedChannel >= 0 then
        ls_Output = loo_Ssh.GetReceivedText(li_CompletedChannel,"utf-8")
        if loo_Ssh.LastMethodSuccess = 0 then
            Write-Debug loo_Ssh.LastErrorText
            destroy loo_Ssh
            return
        end if

        Write-Debug "Channel " + string(li_CompletedChannel) + " finished: " + ls_Output
    end if

    if li_CompletedChannel = -1 then
        Write-Debug "Still waiting for a command to finish..."
    end if

    li_CompletedChannel = loo_Ssh.QuickCmdCheck(li_PollTimeoutMs)
loop

Write-Debug "All quick commands have been collected."

loo_Ssh.Disconnect()


destroy loo_Ssh