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System Programming





Kernel and system programming is the process of creating the software necessary for a computer or device to function and operate other programs. Some operating systems (such as Microsoft Windows) are proprietary, but others, such as the various Linux distributions, are open source.

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Hello Experts,
how does make a bat file for continuous Ping multipal IP with background Colour changes ?
for example:-
start ping -t -l 0
start ping -t -l 0
start ping -t -l 0
start ping -t -l 0
start ping -t -l 0
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Few days back any mail related command ( mailx, mail ,mpack  ) stopped working from one sudo id .
in the logs i get error as dsn=5.6.0, stat=Data format error
but this happens with only one sudo ID-sudo1@my_hostname
another id -sudo2 works fine with any of the mail command

sudo su sudo1
mailx -s "Test mail" someone@example < /tmp/test.file
/home/sudo1/dead.letter... Saved message in /home/sudo1/dead.letter
where from=sudo1@my_hostname
message fails to sent

sudo su sudo2
mailx -s "Test mail" someone@example < /tmp/test.file
where from=sudo2@my_hostname
message successfully sent and received.

Not getting why with one prefix it is sent and other fails ... ?
I have used Octopus Deploy but never Jenkins.

What are some big differences?

A program calls some open source programs.  Can the calling program and all the open source programs be installed in the server?  The reason I ask this is because If all the programs are single threaded and a user can call the open source programs independently of the call made by the main program that runs in the server, there may be collisions.  Is there any issue I should be aware of for a situation like that?
Hello. I have a <asp:CheckBoxList> with 4 ListItems.  I would like to know how I can tell which if any of those checkboxes are checked.  To be more specific I would like to know if the other box is checked and if so a panel should stay visible.  So far this is what I have:

<asp:CheckBoxList ID="cblEduAssistPlans" runat="server" SelectedIndexChanged="cblEduAssistPlans_SelectedIndexChanged" AutoPostBack="true">
                       <asp:ListItem>Individualized education program (IEP)</asp:ListItem>
                       <asp:ListItem>Individualized Family Service Plan (IFSP)</asp:ListItem>
                       <asp:ListItem>504 Plan</asp:ListItem>

right now, when the other box is checked the panel displays (which is what I want).  But if I check on anything else it disappears.  The user should be able to check multiple boxes. But if Other is one of the checked boxes a panel should be visible. If Other is not checked or unchecked the the panel should disappear.  Here is the code that is supposed to run when other is checked.

Protected Sub cblEduAssistPlans_SelectedIndexChanged(sender As Object, e As EventArgs)
        If (cblEduAssistPlans.SelectedValue = "Other") Then
            pnlEduAssistPlans.Visible = True
        End If
    End Sub

Delphi 10.1 Berlin
I have written an app to monitor a folder (new files, delete files) and it does not work in some cases.
- locally it works
- if i start the application on PC1, monitor a folder on the server, add a file in that folder on PC1 it works
- if I add a file to that folder but on the server (not PC1) it does not work (but on some networks this also works!). If I have open the file explorer on PC1 I can see the added file some ms later - but my app doesn't show it.
My code
procedure TForm31.FormCreate(Sender: TObject);
    isf : IShellFolder;
    Eaten, attr : DWord;
    pidl : pItemIDList;
  snh := TShellNotifyHandler.Create(self);
  snh.OnShellNotify := ShellNotifyHandler1;
  snh.ShellMsg := WM_User+100;
  snh.Events := [seDelete, seRenameItem, seCreate];
  snh.Recursive := true;
  isf.ParseDisplayName(self.Handle, nil, PWideChar(ExtractFilePath(ParamStr(0))), Eaten, pidl, attr);
  label1.Caption := ExtractFilePath(ParamStr(0));
  snhHandle := snh.RegisterPIDL(self.Handle,pidl);

procedure TForm31.ShellNotifyHandler1(Sender: TObject; LEvent: TShellEvent;
  pidl1, pidl2: PItemIDList);
    SRec: TSearchRec;
    Res : integer;
  Res := FindFirst(IncludeTrailingPathDelimiter(ExtractFilePath(ParamStr(0)))+'*.*', faAnyFile, SRec);
  while Res = 0 do
    if (SRec.Name <> '.') and (SRec.Name <> '..') then
    Res := FindNext(SRec);

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I imported one project as existing maven project. I am seeing below error while adding tomcat 8 as runtime

An internal error occurred during: "Updating workspace".
assertion failed: Mismatched begin/endOperation

While resolving below errror by going to properties
The superclass "javax.servlet.http.HttpServlet" was not found on the Java Build Path

please advise
while opening team explored in eclipse mars getting below error

Plug-in "com.microsoft.tfs.client.common.ui" was unable to instantiate class "com.microsoft.tfs.client.common.ui.views.TeamExplorerView".

how to resolve this.

Please advise
while trying below example

i did all stepas given

when i execute i do not see 3 mesages there

Example Execution:

Start ActiveMQ and login as admin/admin and click on “Queues” tab.
Start Tomcat and deploy the application. You should see three listeners listening to “firstQueue”.

what is difference between

which one i have to use.

my active mq running on my own windows laptop locally?
when to use http wen to use ftp?
when to use local host when to use ip like number 127.x.y.z...
please advise
hi am geting this error after running the antivirus am not even able to start my pc in safe mode mode am in window 10 The application was unable to start correctly 0xc0000005 am in window 10
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i am working on below example

i wrote my publisher as below

package pubSub;    
import javax.naming.Context;
import javax.naming.InitialContext;                                                                          
import javax.jms.Topic;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.jms.TopicPublisher;

import java.util.Properties;

import javax.jms.DeliveryMode;
import javax.jms.TopicSession;
import javax.jms.TopicConnection;
import javax.jms.TopicConnectionFactory;
public class Publisher
    public static void main(String[] args) throws Exception
    	// Obtain a JNDI connection
    	Properties env = new Properties();
    	env.put(Context.PROVIDER_URL, “http://localhost:8161”);
    	//env.put(Context.SECURITY_PRINCIPAL, “weblogic”);
    	//env.put(Context.SECURITY_CREDENTIALS, “weblogic”);

    	InitialContext ctx = new InitialContext(env);
       // get the initial context
       InitialContext ctx = new InitialContext();
       // lookup the topic object
       Topic topic = (Topic) ctx.lookup("topic/topic0");

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Hi Experts

Could you explain how was the mainframes programs strategy to deal with low hardware resouces, decades ago, when developing banking applications like checking accounts, legal accounting, etc. a typical area with huge amount of data.

I guess there was one computer designated to treat each big agency data and then one other only to sumarize. Am I right?
Could you give details, mainly if you lived this situation?

Thanks in advance!
How to resolve this?


I am reading about nested loop here

for (int i = 1; i <= 5; i++) {
 for (int j = 1; j <= i; j++) {

Think of a nested loop as a race track within a race track. When you begin each lap on the main oval, you veer into another track inside the original (the nested track/loop). You may go around any number of times within the smaller track before looping around the main one. Then it starts over again until you've done the required number of laps on the main track. In all, you may go around a thousand times, or many more!

what it means by race track within a race track not able to visualize this image or picture
what it means by each lap on main oval and veer to another track inside original track??

please advise
 let us say i give some random number like 81349 on console i should see output as by ascending order of each digit in each line how to achieve that as well

    3 3
   4 4 4
 8 8 8 8
9 9 9 9 9

how to to achive this
please advise

i am going through below link


eclipse what is difference between control1 and control 2 when to use which one?

please advise
I just bought a golf cart  that has a pro link monitor. Is it possible to reprogram for the gps when the golf course doesn't have the system. I basically just want the gps.
I am curious about finding the cost to a big bank to process something like a bank transfer from one account to another...

I am thinking about my bank, where I have two accounts, where I may move a few hundred dollars from one account to another.

Is the cost less than a penny for such a transaction for a website or an iPhone app to make such a transfer? I assume there are overhead costs where auditors review blocks of transactions, but I am not asking about that. Just the marginal cost for a hosted and highly secure website to process a transaction.

Does anyone have an idea about this?
i need ideas (or a script) how to search all MAC Addresses of a windows system and pass these as parameter to an external program...with PERL.

script should do the following:
1. get all MAC-Adresses (LAN1, LAN2, WLAN,...)

2. start external programm and pass every MAC (one after another) ... possible within a loop
extProg.exe AA-AA-AA-AA-AA-AA
extProg.exe BB-BB-BB-BB-BB-BB
extProg.exe CC-CC-CC-CC-CC-CC-CC
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In Microsoft Access, I have a form which currently opens up a number of pdf's (currently in Acrobat Reader). My goal is to open up the same number of pdf's in IE, but have them grouped by color. The way the sort of the list is made, the first tab in a group is an image of a purchase order, the following tabs are pdf's of vendor invoices. Often times there is a one to one relationship between purchase order and invoice, however on a fairly regular basis there may be more than one invoice to the purchase order. I would like to make it clear to the user by colored tabs, the relationship of Purchase Orders to Invoices.

The selection criteria and Path has been commented out. Printing works fine, but is also commented out at the moment.

Private Sub Command0_Click()
Dim db As Database
Dim rst As DAO.Recordset
Dim StrSQL As String
Dim PathName As String
Dim PO As String

Set db = CurrentDb()


Set rst = db.OpenRecordset(kaySQL, dbOpenDynaset, dbSeeChanges)
Do Until rst.EOF
  PathName = "SomePath" & rst("Image-no") & ".PDF"

 CreateObject("Shell.Application").Namespace(0).ParseName(PathName).InvokeVerb ("Open")
 'CreateObject("Shell.Application").Namespace(0).ParseName(PathName).InvokeVerb ("Print")


End Sub
I saw some script that in our applications server has the gawk.exe with parameter as  below, do anyone here familiar with gawk and mind to explain what is this parameter does ?

gawk.exe "!x[$0]++"
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.gp.com/Patient"
	xmlns:tns="http://www.gp.com/Patient" elementFormDefault="qualified">

	<element name="patient" type="tns:Patient" />

	<complexType name="Patient">

			<element name="id" type="tns:ID" />
			<element name="name" type="tns:string15chars" />
			<element name="age" type="int" />
			<element name="dob" type="date" />
			<element name="email" type="string" />
			<element name="gender" type="tns:genderEnum" />
			<element name="phone" type="string" />



	<simpleType name="ID">
		<restriction base="int">
			<pattern value="[0-9]*"></pattern>

	<simpleType name="string15chars">
		<restriction base="string">
			<pattern value="15"></pattern>

	<simpleType name="genderEnum">
		<restriction base="string">
			<enumeration value="M"/>
			<enumeration value="F"/>


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Based on aboveXSD i generated below XML which gives error at line 4 of XML as
Multiple annotations found at this line:
      - cvc-type.3.1.3: The value 'Maaa' of element 'tns:name' is not valid.
      - cvc-pattern-valid: Value 'Maaa' is not facet-valid with respect to pattern '15' for type

<?xml version="1.0" encoding="UTF-8"?>
<tns:patient xmlns:tns="http://www.gp.com/Patient" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.gp.com/Patient Patient.xsd ">

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why i am getitng this error and how to fix it. i using eclipse for this as IDE.
any other open source XML IDEs bettr than eclipse to work on these simple xml, XSDs etc
please advise
private void FileDataRequest(StreamedFileDataRequest r)


MemoryStream m = new MemoryStream();

r = m.AsOutputStream as StreamedFileDataRequest;
void loop(){
StorageLibrary l = await StorageLibrary.GetLibraryAsync(FromKnownId.Pictures);

Scrollviewer scrollviewer = new Scrollviewer();

RenderTargetBitmap r = null;

 r = new RenderTargetBitmap();

                await r.RenderAsync(scrollviewer);


                var file0 = await l.SaveFolder.CreateFileAsync("poikidiki");

                await FileIO.WriteBufferAsync(file0, await r.GetPixelsAsync());

                Windows.Storage.Streams.IRandomAccessStream b = await file0.OpenAsync(FileAccessMode.ReadWrite);


                var file = await StorageFile.CreateStreamedFileAsync("effort06.jpg", new StreamedFileDataRequestedHandler(FileDataRequest),Windows.Storage.Streams.RandomAccessStreamReference.CreateFromFile(file0));


                await file.CopyAsync(l.SaveFolder);


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I have this:

it doesn't copy the bytes to the streamed file.

help appreciated
HOW TO CONVERT * char to string (linha):

const unsigned char
*menino1 = (const unsigned char *)0;

menino1 = p - 17;

string linha = menino[1]+menino[2]+menino[3]+menino[4]+menino[5];


for above challenge
Map-1 > mapAB4
prev  |  next  |  chance

Modify and return the given map as follows: if the keys "a" and "b" have values that have different lengths, then set "c" to have the longer value. If the values exist and have the same length, change them both to the empty string in the map.

mapAB4({"a": "aaa", "b": "bb", "c": "cake"}) → {"a": "aaa", "b": "bb", "c": "aaa"}
mapAB4({"a": "aa", "b": "bbb", "c": "cake"}) → {"a": "aa", "b": "bbb", "c": "bbb"}
mapAB4({"a": "aa", "b": "bbb"}) → {"a": "aa", "b": "bbb", "c": "bbb"}

what are input parameters for the method.

what is the return for it?

"a": "aaa", "b": "bb", "c": "cake"//is these are bunch of string values pretending to be key and value for a map??

please advise on how to understand and approach this challenge

System Programming





Kernel and system programming is the process of creating the software necessary for a computer or device to function and operate other programs. Some operating systems (such as Microsoft Windows) are proprietary, but others, such as the various Linux distributions, are open source.