Programs & Examples On #Microkernel

Microkernel is a highly limited kernel that usually only supports address space management, thread management and inter-process communication when other parts of the OS run in userspace.

Could not load type from assembly error

I experienced a similar issue in Visual Studio 2017 using MSTest as the testing framework. I was receiving System.TypeLoadException exceptions when running some (not all) unit tests, but those unit tests would pass when debugged. I ultimately did the following which solved the problem:

  1. Open the Local.testsettings file in the solution
  2. Go to the "Unit Test" settings
  3. Uncheck the "Use the Load Context for assemblies in the test directory." checkbox

After taking these steps all unit tests started passing when run.

How to run Java program in command prompt

You can use javac *.java command to compile all you java sources. Also you should learn a little about classpath because it seems that you should set appropriate classpath for succesful compilation (because your IDE use some libraries for building WebService clients). Also I can recommend you to check wich command your IDE use to build your project.

Appending an id to a list if not already present in a string

A more pythonic way, without using set is as follows:

lst = [1, 2, 3, 4]
lst.append(3) if 3 not in lst else lst

Extracting the top 5 maximum values in excel

There 3 functions you want to look at here:

I ran a sample in Excel with your OPS values in Column B and Players in Column C, see below:

Excel sample

  • In Cells A13 to A17, the values 1 to 5 were inserted to specify the nth highest value.
  • In Cell B13, the following formula was added: =LARGE($B$2:$B$11, A13)
  • In Cell C13, the following formula was added: =INDEX($C$2:$C$11,MATCH(B13,$B$2:$B$11,0))
  • These formulae get the highest ranking OPS and Player based on the value in A13.
  • Simply select and drag to copy these formulae down to the next 4 cells which will reference the corresponding ranking in Column A.

The type or namespace name does not exist in the namespace 'System.Web.Mvc'

I had the same problem - my scenario was that I was referencing the new System.Web.Mvc.dll from a lib folder and I did not have "Copy Local" set to true. The application was then reverting back to the version in the GAC which didn't have the correct namespaces (Html, Ajax etc) in it and was giving me the run time error.

Setting HTTP headers

I know this is a different twist on the answer, but isn't this more of a concern for a web server? For example, nginx, could help.

The ngx_http_headers_module module allows adding the “Expires” and “Cache-Control” header fields, and arbitrary fields, to a response header


    add_header Access-Control-Allow-Methods POST

Adding nginx in front of your go service in production seems wise. It provides a lot more feature for authorizing, logging,and modifying requests. Also, it gives the ability to control who has access to your service and not only that but one can specify different behavior for specific locations in your app, as demonstrated above.

I could go on about why to use a web server with your go api, but I think that's a topic for another discussion.

How to manage exceptions thrown in filters in Spring?

When you want to test a state of application and in case of a problem return HTTP error I would suggest a filter. The filter below handles all HTTP requests. The shortest solution in Spring Boot with a javax filter.

In the implementation can be various conditions. In my case the applicationManager testing if the application is ready.

import ...ApplicationManager;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import javax.servlet.*;
import javax.servlet.http.HttpServletResponse;

public class SystemIsReadyFilter implements Filter {

    private ApplicationManager applicationManager;

    public void init(FilterConfig filterConfig) throws ServletException {}

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        if (!applicationManager.isApplicationReady()) {
            ((HttpServletResponse) response).sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE, "The service is booting.");
        } else {
            chain.doFilter(request, response);

    public void destroy() {}

How do I find the distance between two points?

Let's not forget math.hypot:

dist = math.hypot(x2-x1, y2-y1)

Here's hypot as part of a snippet to compute the length of a path defined by a list of (x, y) tuples:

from math import hypot

pts = [

# Py2 syntax - no longer allowed in Py3
# ptdiff = lambda (p1,p2): (p1[0]-p2[0], p1[1]-p2[1])
ptdiff = lambda p1, p2: (p1[0]-p2[0], p1[1]-p2[1])

diffs = (ptdiff(p1, p2) for p1, p2 in zip (pts, pts[1:]))
path = sum(hypot(*d) for d in  diffs)

Assembly - JG/JNLE/JL/JNGE after CMP

Wikibooks has a fairly good summary of jump instructions. Basically, there's actually two stages:

cmp_instruction op1, op2

Which sets various flags based on the result, and

jmp_conditional_instruction address

which will execute the jump based on the results of those flags.

Compare (cmp) will basically compute the subtraction op1-op2, however, this is not stored; instead only flag results are set. So if you did cmp eax, ebx that's the same as saying eax-ebx - then deciding based on whether that is positive, negative or zero which flags to set.

More detailed reference here.

URLEncoder not able to translate space character

Check out the class.

HTML5 Canvas: Zooming

Canvas zoom and pan

<!DOCTYPE html>_x000D_
<canvas id="myCanvas" width="" height=""_x000D_
style="border:1px solid #d3d3d3;">_x000D_
Your browser does not support the canvas element._x000D_
var ox=0,oy=0,px=0,py=0,scx=1,scy=1;_x000D_
var canvas = document.getElementById("myCanvas");_x000D_
canvas.onmousedown=(e)=>{px=e.x;py=e.y;canvas.onmousemove=(e)=>{ox-=(e.x-px);oy-=(e.y-py);px=e.x;py=e.y;} } _x000D_
canvas.onwheel =(e)=>{let bfzx,bfzy,afzx,afzy;[bfzx,bfzy]=StoW(e.x,e.y);scx-=10*scx/e.deltaY;scy-=10*scy/e.deltaY;_x000D_
var ctx = canvas.getContext("2d");_x000D_
function draw(){_x000D_
for(let i=0;i<=100;i+=10){_x000D_
let sx=0,sy=i;_x000D_
let ex=100,ey=i;_x000D_
ctx.moveTo(sx, sy);_x000D_
ctx.lineTo(ex, ey);_x000D_
for(let i=0;i<=100;i+=10){_x000D_
let sx=i,sy=0;_x000D_
let ex=i,ey=100;_x000D_
ctx.moveTo(sx, sy);_x000D_
ctx.lineTo(ex, ey);_x000D_
function WtoS(wx,wy){_x000D_
let sx=(wx-ox)*scx;_x000D_
let sy=(wy-oy)*scy;_x000D_
function StoW(sx,sy){_x000D_
let wx=sx/scx+ox;_x000D_
let wy=sy/scy+oy;_x000D_

Get list of data-* attributes using javascript / jQuery

A pure JavaScript solution ought to be offered as well, as the solution is not difficult:

var a = [], function(at) { return /^data-/.test(; });

This gives an array of attribute objects, which have name and value properties:

if (a.length) {
    var firstAttributeName = a[0].name;
    var firstAttributeValue = a[0].value;

Edit: To take it a step further, you can get a dictionary by iterating the attributes and populating a data object:

var data = {};
[], function(attr) {
    if (/^data-/.test( {
        var camelCaseName =, function ($0, $1) {
            return $1.toUpperCase();
        data[camelCaseName] = attr.value;

You could then access the value of, for example, data-my-value="2" as data.myValue;

Edit: If you wanted to set data attributes on your element programmatically from an object, you could:

Object.keys(data).forEach(function(key) {
    var attrName = "data-" + key.replace(/[A-Z]/g, function($0) {
        return "-" + $0.toLowerCase();
    el.setAttribute(attrName, data[key]);

EDIT: If you are using babel or TypeScript, or coding only for es6 browsers, this is a nice place to use es6 arrow functions, and shorten the code a bit:

var a = [], at => /^data-/.test(;

How do you add swap to an EC2 instance?

Try swapspace

Most distros have it packaged.

On EC2 you might want to change "swappath" to /mnt or high-iops disk.

Read file from resources folder in Spring Boot

if you have for example config folder under Resources folder I tried this Class working perfectly hope be useful

File file = ResourceUtils.getFile("classpath:config/sample.txt")

//Read File Content
String content = new String(Files.readAllBytes(file.toPath()));

Git diff against a stash

If the branch that your stashed changes are based on has changed in the meantime, this command may be useful:

git diff stash@{0}^!

This compares the stash against the commit it is based on.

Command to close an application of console?

return; will exit a method in C#.

See code snippet below

using System;

namespace Exercise_strings
    class Program
        static void Main(string[] args)
           Console.WriteLine("Input string separated by -");

            var stringInput = Console.ReadLine();

            if (string.IsNullOrWhiteSpace(stringInput))
                Console.WriteLine("Nothing entered");

So in this case if a user enters a null string or whitespace, the use of the return method terminates the Main method elegantly.

CSS: center element within a <div> element

mine would like magic.

html, body {
 height: 100%;

  display: -ms-flexbox;
  display: -webkit-box;
  display: flex;
  -ms-flex-align: center;
  -ms-flex-pack: center;
  -webkit-box-align: center;
  align-items: center;
  -webkit-box-pack: center;
  justify-content: center;

<div class="flex-container">

How to find out what type of a Mat object is with Mat::type() in OpenCV

For debugging purposes in case you want to look up a raw Mat::type in a debugger:

|        | C1 | C2 | C3 | C4 | C(5) | C(6) | C(7) | C(8) |
| CV_8U  |  0 |  8 | 16 | 24 |   32 |   40 |   48 |   56 |
| CV_8S  |  1 |  9 | 17 | 25 |   33 |   41 |   49 |   57 |
| CV_16U |  2 | 10 | 18 | 26 |   34 |   42 |   50 |   58 |
| CV_16S |  3 | 11 | 19 | 27 |   35 |   43 |   51 |   59 |
| CV_32S |  4 | 12 | 20 | 28 |   36 |   44 |   52 |   60 |
| CV_32F |  5 | 13 | 21 | 29 |   37 |   45 |   53 |   61 |
| CV_64F |  6 | 14 | 22 | 30 |   38 |   46 |   54 |   62 |

So for example, if type = 30 then OpenCV data type is CV_64FC4. If type = 50 then the OpenCV data type is CV_16UC(7).

What is the correct way to read a serial port using .NET framework?

Could you try something like this for example I think what you are wanting to utilize is the port.ReadExisting() Method

 using System;
 using System.IO.Ports;

 class SerialPortProgram 
  // Create the serial port with basic settings 
    private SerialPort port = new   SerialPort("COM1",
      9600, Parity.None, 8, StopBits.One); 
    static void Main(string[] args) 
      // Instatiate this 

    private static void SerialPortProgram() 
        Console.WriteLine("Incoming Data:");
         // Attach a method to be called when there
         // is data waiting in the port's buffer 
        port.DataReceived += new SerialDataReceivedEventHandler(port_DataReceived); 
        // Begin communications 
        // Enter an application loop to keep this thread alive 

    private void port_DataReceived(object sender, SerialDataReceivedEventArgs e) 
       // Show all the incoming data in the port's buffer

Or is you want to do it based on what you were trying to do , you can try this

public class MySerialReader : IDisposable
  private SerialPort serialPort;
  private Queue<byte> recievedData = new Queue<byte>();

  public MySerialReader()
    serialPort = new SerialPort();
    serialPort.DataReceived += serialPort_DataReceived;

  void serialPort_DataReceived(object s, SerialDataReceivedEventArgs e)
    byte[] data = new byte[serialPort.BytesToRead];
    serialPort.Read(data, 0, data.Length);
    data.ToList().ForEach(b => recievedData.Enqueue(b));

  void processData()
    // Determine if we have a "packet" in the queue
    if (recievedData.Count > 50)
        var packet = Enumerable.Range(0, 50).Select(i => recievedData.Dequeue());

  public void Dispose()
        if (serialPort != null)

Get all unique values in a JavaScript array (remove duplicates)

Now using sets you can remove duplicates and convert them back to the array.

var names = ["Mike","Matt","Nancy", "Matt","Adam","Jenny","Nancy","Carl"];_x000D_
console.log([ Set(names)])

Another solution is to use sort & filter

var names = ["Mike","Matt","Nancy", "Matt","Adam","Jenny","Nancy","Carl"];_x000D_
var namesSorted = names.sort();_x000D_
const result = namesSorted.filter((e, i) => namesSorted[i] != namesSorted[i+1]);_x000D_

how to get the last part of a string before a certain character?

Difference between split and partition is split returns the list without delimiter and will split where ever it gets delimiter in string i.e.

x = ''

a,b,c = x.split(-)

and partition will divide the string with only first delimiter and will only return 3 values in list

x = ''
a,b,c = x.partition('-')

so as you want last value you can use rpartition it works in same way but it will find delimiter from end of string

x = ''
a,b,c = x.partition('-')

How to create an exit message

If you want to denote an actual error in your code, you could raise a RuntimeError exception:

raise RuntimeError, 'Message goes here'

This will print a stacktrace, the type of the exception being raised and the message that you provided. Depending on your users, a stacktrace might be too scary, and the actual message might get lost in the noise. On the other hand, if you die because of an actual error, a stacktrace will give you additional information for debugging.

Add primary key to existing table

I think something like this should work

-- drop current primary key constraint
ALTER TABLE dbo.persion 

-- add new auto incremented field
ALTER TABLE dbo.persion 

-- create new primary key constraint
ALTER TABLE dbo.persion 

CS0234: Mvc does not exist in the System.Web namespace

None of previous answers worked for me.

I noticed that my project was referencing another project using the System.Web.Mvc reference from the .NET Framework.

I just deleted that assembly and added the "Microsoft.AspNet.Mvc" NuGet package and that fixed my problem.

java: HashMap<String, int> not working

You cannot use primitive types in HashMap. int, or double don't work. You have to use its enclosing type. for an example

Map<String,Integer> m = new HashMap<String,Integer>();

Now both are objects, so this will work.

How to export a MySQL database to JSON?

It may be asking too much of MySQL to expect it to produce well formed json directly from a query. Instead, consider producing something more convenient, like CSV (using the INTO OUTFILE '/path/to/output.csv' FIELDS TERMINATED BY ',' snippet you already know) and then transforming the results into json in a language with built in support for it, like python or php.

Edit python example, using the fine SQLAlchemy:

class Student(object):
    '''The model, a plain, ol python class'''
    def __init__(self, name, email, enrolled): = name = email
        self.enrolled = enrolled

    def __repr__(self):
        return "<Student(%r, %r)>" % (,

    def make_dict(self):
        return {'name':, 'email':}

import sqlalchemy
metadata = sqlalchemy.MetaData()
students_table = sqlalchemy.Table('students', metadata,
        sqlalchemy.Column('id', sqlalchemy.Integer, primary_key=True),
        sqlalchemy.Column('name', sqlalchemy.String(100)),
        sqlalchemy.Column('email', sqlalchemy.String(100)),
        sqlalchemy.Column('enrolled', sqlalchemy.Date)

# connect the database.  substitute the needed values.
engine = sqlalchemy.create_engine('mysql://user:pass@host/database')

# if needed, create the table:

# map the model to the table
import sqlalchemy.orm
sqlalchemy.orm.mapper(Student, students_table)

# now you can issue queries against the database using the mapping:
non_students = engine.query(Student).filter_by(enrolled=None)

# and lets make some json out of it:
import json
non_students_dicts = ( student.make_dict() for student in non_students)
students_json = json.dumps(non_students_dicts)

Unit testing with mockito for constructors

Include this line on top of your test class

@PrepareForTest({ First.class })

IE8 crashes when loading website - res://ieframe.dll/acr_error.htm

Try looking for Windows Error Reporting events in the affected machine's Event Viewer, specifically for iexplore.exe. That might give you a pointer for what component is getting loaded in IE that is causing the crash. Even more precise would be to launch IE under a debugger (e.g. windbg), repro the crash and then get a call stack. If you have a bad 3rd party add-on, it should be towards the top of the call stack. Though you said that it "isn't really an option" it will be important for you to identify a possible incompatibility and either reach out to the add-on developer, or workaround the issue on your side.

How to save a Seaborn plot into a file

The suggested solutions are incompatible with Seaborn 0.8.1

giving the following errors because the Seaborn interface has changed:

AttributeError: 'AxesSubplot' object has no attribute 'fig'
When trying to access the figure

AttributeError: 'AxesSubplot' object has no attribute 'savefig'
when trying to use the savefig directly as a function

The following calls allow you to access the figure (Seaborn 0.8.1 compatible):

swarm_plot = sns.swarmplot(...)
fig = swarm_plot.get_figure()

as seen previously in this answer.

UPDATE: I have recently used PairGrid object from seaborn to generate a plot similar to the one in this example. In this case, since GridPlot is not a plot object like, for example, sns.swarmplot, it has no get_figure() function. It is possible to directly access the matplotlib figure by

fig = myGridPlotObject.fig

Like previously suggested in other posts in this thread.

SQL Error: ORA-00913: too many values

If you are having 112 columns in one single table and you would like to insert data from source table, you could do as

create table employees as select * from source_employees where employee_id=100;

Or from sqlplus do as

copy from source_schema/password insert employees using select * from 
source_employees where employee_id=100;

OS X Terminal shortcut: Jump to beginning/end of line

I am not sure if this will work for you (I still use OS 10.8), but these work for my terminal:

home = move cursor to the start of the line
shift+end = move cursor to the end of the line

alt+leftArrow = move one "word" to the left
alt+rightArrow = move one "word" to the right

Hope this helps!

Why doesn't java.util.Set have get(int index)?

Just adding one point that was not mentioned in mmyers' answer.

If I know I want the first item, I can use set.iterator().next(), but otherwise it seems I have to cast to an Array to retrieve an item at a specific index?

What are the appropriate ways of retrieving data from a set? (other than using an iterator)

You should also familiarise yourself with the SortedSet interface (whose most common implementation is TreeSet).

A SortedSet is a Set (i.e. elements are unique) that is kept ordered by the natural ordering of the elements or using some Comparator. You can easily access the first and last items using first() and last() methods. A SortedSet comes in handy every once in a while, when you need to keep your collection both duplicate-free and ordered in a certain way.

Edit: If you need a Set whose elements are kept in insertion-order (much like a List), take a look at LinkedHashSet.

What is the difference between an Instance and an Object?

If we see the Definition of Object and Instance object -

Memory allocated for the member of class at run time is called object or object is the instance of Class.

Let us see the Definition of instance -

Memory allocated For Any at run time is called as instance variable.

Now understand the meaning of any run time memory allocation happen in C also through Malloc, Calloc, Realloc such:

struct p

p *t1
t1=(p) malloc(sizeof(p))

So here also we are allocating run time memory allocation but here we call as instance so t1 is instance here we can not say t1 as object so Every object is the instance of Class but every Instance is not Object.

Search a string in a file and delete it from this file by Shell Script

Try the vim-way:

ex -s +"g/foo/d" -cwq file.txt

SQL how to increase or decrease one for a int column in one command

@dotjoe It is cheaper to update and check @@rowcount, do an insert after then fact.

Exceptions are expensive && updates are more frequent

Suggestion: If you want to be uber performant in your DAL, make the front end pass in a unique ID for the row to be updated, if null insert.

The DALs should be CRUD, and not need to worry about being stateless.

If you make it stateless, With good indexes, you will not see a diff with the following SQL vs 1 statement. IF (select top 1 * form x where PK=@ID) Insert else update

How can I get the line number which threw exception?

If you need the line number for more than just the formatted stack trace you get from Exception.StackTrace, you can use the StackTrace class:

    throw new Exception();
catch (Exception ex)
    // Get stack trace for the exception with source file information
    var st = new StackTrace(ex, true);
    // Get the top stack frame
    var frame = st.GetFrame(0);
    // Get the line number from the stack frame
    var line = frame.GetFileLineNumber();

Note that this will only work if there is a pdb file available for the assembly.

android.os.NetworkOnMainThreadException with android 4.2

Please make sure that you don't do any network access on UI Thread, instead do it in Async Task

The reason why your application crashes on Android versions 3.0 and above, but works fine on Android 2.x is because since HoneyComb are much stricter about abuse against the UI Thread. For example, when an Android device running HoneyComb or above detects a network access on the UI thread, a NetworkOnMainThreadException will be thrown.

See this

how to access iFrame parent page using jquery?

To find in the parent of the iFrame use:

$('#parentPrice', window.parent.document).html();

The second parameter for the $() wrapper is the context in which to search. This defaults to document.

Bootstrap center heading

.text-left {
  text-align: left;

.text-right {
  text-align: right;

.text-center {
  text-align: center;

bootstrap has added three css classes for text align.

How do I tokenize a string in C++?

A solution using regex_token_iterators:

#include <iostream>
#include <regex>
#include <string>

using namespace std;

int main()
    string str("The quick brown fox");

    regex reg("\\s+");

    sregex_token_iterator iter(str.begin(), str.end(), reg, -1);
    sregex_token_iterator end;

    vector<string> vec(iter, end);

    for (auto a : vec)
        cout << a << endl;

How to use Google App Engine with my own naked domain (not subdomain)?

Just managed to sort this finally after hours. The www subdomain was pointing to Sites, but the front end wasn't showing me that.

After taking the plunge and setting the CNAME to, and enabling / disabling Sites a couple of times (see the comment from Rodrigo Moraes on I was able to set the Sites address to use the www subdomain.

I was then able to change it away from using the www subdomain, at which point the appengine app allowed me to specify the www subdomain.

That is one dirty fix - basically turning on and off Sites until it works!

Convert HttpPostedFileBase to byte[]

You can read it from the input stream:

public ActionResult ManagePhotos(ManagePhotos model)
    if (ModelState.IsValid)
        byte[] image = new byte[model.File.ContentLength];
        model.File.InputStream.Read(image, 0, image.Length); 

        // TODO: Do something with the byte array here

And if you intend to directly save the file to the disk you could use the model.File.SaveAs method. You might find the following blog post useful.

"Too many values to unpack" Exception

Most likely there is an error somewhere in the get_profile() call. In your view, before you return the request object, put this line:


It should raise the error, and give you a more detailed traceback, which you can then use to further debug.

POST request via RestTemplate in JSON

The "415 Unsupported Media Type" error is telling you that the server will not accept your POST request. Your request is absolutely fine, it's the server that's mis-configured.

MappingJacksonHttpMessageConverter will automatically set the request content-type header to application/json, and my guess is that your server is rejecting that. You haven't told us anything about your server setup, though, so I can't really advise you on that.

Bash script to run php script

A previous poster said..

If you have PHP installed as a command line tool… your shebang (#!) line needs to look like this: #!/usr/bin/php

While this could be true… just because you can type in php does NOT necessarily mean that's where php is going to be... /usr/bin/php is A common location… but as with any shebang… it needs to be tailored to YOUR env.

a quick way to find out WHERE YOUR particular executable is located on your $PATH, try.. ?which -a php ENTER, which for me looks like..

php is /usr/local/php5/bin/php
php is /usr/bin/php
php is /usr/local/bin/php
php is /Library/WebServer/CGI-Executables/php

The first one is the default i'd get if I just typed in php at a command prompt… but I can use any of them in a shebang, or directly… You can also combine the executable name with env, as is often seen, but I don't really know much about / trust that. XOXO.

How to execute raw queries with Laravel 5.1?

you can run raw query like this way too.


Using cURL with a username and password?

Usually CURL command refer to as

curl\?param\=ParamValue -u USERNAME:PASSWORD

if you don't have any password or want to skip command prompt to demand for password simple leave the password section blank.

i.e. curl\?param\=ParamValue -u USERNAME:

How to avoid Python/Pandas creating an index in a saved csv?

If you want a good format the next statement is the best:

dataframe_prediction.to_csv('filename.csv', sep=',', encoding='utf-8', index=False)

In this case you have got a csv file with ',' as separate between columns and utf-8 format. In addition, numerical index won't appear.

How do I view the SSIS packages in SQL Server Management Studio?

  1. Open SQL server Management Studio.
  2. Go to Connect to Server and select the Server Type as Integration Services and give the Server Name then click connect.
  3. Go to Object Explorer on the left corner.
  4. You can see the Stored Package folder in Object Explorer.
  5. Expand the Stored Package folder, here you can see the SSIS interfaces.

Reading my own Jar's Manifest

A simpler way to do this is to use getPackage(). For example, to get Implementation-Version:


The 'json' native gem requires installed build tools

Follow the Instructions from the Ruby Installer Developer Kit Wiki:

  1. Download Ruby 1.9.3 from
  2. Download DevKit file from
  3. Extract DevKit to path C:\Ruby193\DevKit
  4. Run cd C:\Ruby193\DevKit
  5. Run ruby dk.rb init
  6. Run ruby dk.rb review
  7. Run ruby dk.rb install

To return to the problem at hand, you should be able to install JSON (or otherwise test that your DevKit successfully installed) by running the following commands which will perform an install of the JSON gem and then use it:

gem install json --platform=ruby
ruby -rubygems -e "require 'json'; puts JSON.load('[42]').inspect"

MongoDB: exception in initAndListen: 20 Attempted to create a lock file on a read-only directory: /data/db, terminating

On a Mac, I had to do the following:

sudo chown -R $USER /data/db
sudo chown -R $USER /tmp/

because there was also a file inside /tmp which Mongo also needed access

VNC viewer with multiple monitors

tightVNC 2.5.X and even pre 2.5 supports multi monitor. When you connect, you get a huge virtual monitor. However, this is also has disadvantages. UltaVNC (Tho when I tried it, was buggy in this area) allows you to connect to one huge virtual monitor or just to 1 screen at a time. (With a button to cycle through them) TightVNC also plan to support such a feature.. (When , no idea) This feature is important as if you have large multi monitors and connecting over a reasonably slow link.. The screen updates are just to slow.. Cutting down to one monitor to focus on is desirable.

I like tightVNC, but UltraVNC seems to have a few more features right now..

I have found tightVNC more solid. And that is why I have stuck with it.

I would try both. They both work well, but I imagine one would suite slightly more then the other.

Keeping session alive with Curl and PHP

This is how you do CURL with sessions

//initial request with login data

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, '');
curl_setopt($ch, CURLOPT_USERAGENT,'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/32.0.1700.107 Chrome/32.0.1700.107 Safari/537.36');
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, "username=XXXXX&password=XXXXX");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_COOKIESESSION, true);
curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookie-name');  //could be empty, but cause problems on some hosts
curl_setopt($ch, CURLOPT_COOKIEFILE, '/var/www/ip4.x/file/tmp');  //could be empty, but cause problems on some hosts
$answer = curl_exec($ch);
if (curl_error($ch)) {
    echo curl_error($ch);

//another request preserving the session

curl_setopt($ch, CURLOPT_URL, '');
curl_setopt($ch, CURLOPT_POST, false);
curl_setopt($ch, CURLOPT_POSTFIELDS, "");
$answer = curl_exec($ch);
if (curl_error($ch)) {
    echo curl_error($ch);

I've seen this on ImpressPages

How to hash a string into 8 digits?

I am sharing our nodejs implementation of the solution as implemented by @Raymond Hettinger.

var crypto = require('crypto');
var s = 'she sells sea shells by the sea shore';
console.log(BigInt('0x' + crypto.createHash('sha1').update(s).digest('hex'))%(10n ** 8n));

What is the difference between concurrent programming and parallel programming?

In programming, concurrency is the composition of independently executing processes, while parallelism is the simultaneous execution of (possibly related) computations.
- Andrew Gerrand -


Concurrency is the composition of independently executing computations. Concurrency is a way to structure software, particularly as a way to write clean code that interacts well with the real world. It is not parallelism.

Concurrency is not parallelism, although it enables parallelism. If you have only one processor, your program can still be concurrent but it cannot be parallel. On the other hand, a well-written concurrent program might run efficiently in parallel on a multiprocessor. That property could be important...
- Rob Pike -

To understand the difference, I strongly recommend to see this Rob Pike(one of Golang creators)'s video. Concurrency Is Not Parallelism

Enable CORS in fetch api

Browser have cross domain security at client side which verify that server allowed to fetch data from your domain. If Access-Control-Allow-Origin not available in response header, browser disallow to use response in your JavaScript code and throw exception at network level. You need to configure cors at your server side.

You can fetch request using mode: 'cors'. In this situation browser will not throw execption for cross domain, but browser will not give response in your javascript function.

So in both condition you need to configure cors in your server or you need to use custom proxy server.

Chart.js canvas resize

As jcmiller11 suggested, setting the width and height helps. A slightly nicer solution is to retrieve the width and height of the canvas before drawing the chart. Then using those numbers for setting the chart on each subsequent re-draw of the chart. This makes sure there are no constants in the javascript code.

ctx.canvas.originalwidth = ctx.canvas.width;
ctx.canvas.originalheight = ctx.canvas.height;

function drawchart() {
    ctx.canvas.width = ctx.canvas.originalwidth;
    ctx.canvas.height = ctx.canvas.originalheight;

    var chartctx = new Chart(ctx);
    myNewBarChart = chartctx.Bar(data, chartSettings); 

Find the max of two or more columns with pandas

@DSM's answer is perfectly fine in almost any normal scenario. But if you're the type of programmer who wants to go a little deeper than the surface level, you might be interested to know that it is a little faster to call numpy functions on the underlying .to_numpy() (or .values for <0.24) array instead of directly calling the (cythonized) functions defined on the DataFrame/Series objects.

For example, you can use ndarray.max() along the first axis.

# Data borrowed from @DSM's post.
df = pd.DataFrame({"A": [1,2,3], "B": [-2, 8, 1]})
   A  B
0  1 -2
1  2  8
2  3  1

df['C'] = df[['A', 'B']].values.max(1)
# Or, assuming "A" and "B" are the only columns, 
# df['C'] = df.values.max(1) 

   A  B  C
0  1 -2  1
1  2  8  8
2  3  1  3 

If your data has NaNs, you will need numpy.nanmax:

df['C'] = np.nanmax(df.values, axis=1)

   A  B  C
0  1 -2  1
1  2  8  8
2  3  1  3 

You can also use numpy.maximum.reduce. numpy.maximum is a ufunc (Universal Function), and every ufunc has a reduce:

df['C'] = np.maximum.reduce(df['A', 'B']].values, axis=1)
# df['C'] = np.maximum.reduce(df[['A', 'B']], axis=1)
# df['C'] = np.maximum.reduce(df, axis=1)

   A  B  C
0  1 -2  1
1  2  8  8
2  3  1  3

enter image description here

np.maximum.reduce and np.max appear to be more or less the same (for most normal sized DataFrames)—and happen to be a shade faster than DataFrame.max. I imagine this difference roughly remains constant, and is due to internal overhead (indexing alignment, handling NaNs, etc).

The graph was generated using perfplot. Benchmarking code, for reference:

import pandas as pd
import perfplot

df_ = pd.DataFrame(np.random.randn(5, 1000))
    setup=lambda n: pd.concat([df_] * n, ignore_index=True),
        lambda df: df.assign(new=df.max(axis=1)),
        lambda df: df.assign(new=df.values.max(1)),
        lambda df: df.assign(new=np.nanmax(df.values, axis=1)),
        lambda df: df.assign(new=np.maximum.reduce(df.values, axis=1)),
    labels=['df.max', 'np.max', 'np.maximum.reduce', 'np.nanmax'],
    n_range=[2**k for k in range(0, 15)],
    xlabel='N (* len(df))',

Day Name from Date in JS

You could use the Date.getDay() method, which returns 0 for sunday, up to 6 for saturday. So, you could simply create an array with the name for the day names:

var days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
var d = new Date(dateString);
var dayName = days[d.getDay()];

Here dateString is the string you received from the third party API.

Alternatively, if you want the first 3 letters of the day name, you could use the Date object's built-in toString method:

var d = new Date(dateString);
var dayName = d.toString().split(' ')[0];

That will take the first word in the d.toString() output, which will be the 3-letter day name.

Single vs Double quotes (' vs ")

I'm newbie here but I use single quote mark only when I use double quote mark inside the first one. If I'm not clear I show You example:

<p align="center" title='One quote mark at the beginning so now I can
"cite".'> ... </p>

I hope I helped.

How to Detect Browser Back Button event - Cross Browser

Correct answer is already there to answer the question. I want to mention new JavaScript API PerformanceNavigationTiming, it's replacing deprecated performance.navigation.

Following code will log in console "back_forward" if user landed on your page using back or forward button. Take a look at compatibility table before using it in your project.

var perfEntries = performance.getEntriesByType("navigation");
for (var i = 0; i < perfEntries.length; i++) {

Psexec "run as (remote) admin"

Use psexec -s

The s switch will cause it to run under system account which is the same as running an elevated admin prompt. just used it to enable WinRM remotely.

How to add white spaces in HTML paragraph

If you really need then you can use i.e. &nbsp; entity to do that, but remember that fonts used to render your page are usually proportional, so "aligning" with spaces does not really work and looks ugly.

Difference between Static methods and Instance methods

Instance method vs Static method

  1. Instance method can access the instance methods and instance variables directly.

  2. Instance method can access static variables and static methods directly.

  3. Static methods can access the static variables and static methods directly.

  4. Static methods can’t access instance methods and instance variables directly. They must use reference to object. And static method can’t use this keyword as there is no instance for ‘this’ to refer to.

Jquery Open in new Tab (_blank)

Setting links on the page woud require a combination of @Ravi and @ncksllvn's answers:

// Find link in $(".product-item") and set "target" attribute to "_blank".
$(this).find("a").attr("target", "_blank");

For opening the page in another window, see this question: jQuery click _blank And see this reference for options for customization.


You would need something along:

$(document).ready(function() {
  $(".product-item").click(function() {
    var productLink = $(this).find("a");

    productLink.attr("target", "_blank");"href"));

    return false;

Note the usage of .attr():

$element.attr("attribute_name")                   // Get value of attribute.
$element.attr("attribute_name", attribute_value)  // Set value of attribute.

Calling ASP.NET MVC Action Methods from JavaScript

You can set up your element with



onclick= addToWishList(this.value);

Identifier is undefined

Are you missing a function declaration?

void ac_search(uint num_patterns, uint pattern_length, const char *patterns, 
               uint num_records, uint record_length, const char *records, int *matches, Node* trie);

Add it just before your implementation of ac_benchmark_search.

How do I set default values for functions parameters in Matlab?

I believe I found quite a nifty way to deal with this issue, taking up only three lines of code (barring line wraps). The following is lifted directly from a function I am writing, and it seems to work as desired:

defaults = {50/6,3,true,false,[375,20,50,0]}; %set all defaults
defaults(1:nargin-numberForcedParameters) = varargin; %overload with function input
[sigma,shifts,applyDifference,loop,weights] = ...
     defaults{:}; %unfold the cell struct

Just thought I'd share it.

Redis connection to failed - connect ECONNREFUSED

for Windows users, you can use chocolatey to install Redis

choco install redis-64

then run server from


Unable to run Java code with Intellij IDEA

Don't forget the String[] args in your main method. Otherwise, there's no option to run your program:

public static void main(String[] args) {


Javascript regular expression password validation having special characters

When you remake account password make shure it's 8-20 characters include numbers and special characters like ##/* characters like this then verify new password and re enter exact same and should solve the issues with the password verification

Error to run Android Studio

It's probably because you don't have jdk installed in your machine. I had exact same problem in first run. Open a terminal (CTRL+ALT+T) and type: sudo apt-get install openjdk-7-jdk

When done setup Java environment variable. Steps as follows:

  1. sudo gedit /etc/environment
  2. Either in the beginning or end of the file write: JAVA_HOME=/usr/lib/jvm/java-7-openjdk-i386 (location may vary depending on the installation of your Java)
  3. export JAVA_HOME
  4. save and exit editor.
  5. Load the path variable again using the terminal: . /etc/environment

Couple of helpful links for further clarifications:

Hope this helps.

How can I profile C++ code running on Linux?

Newer kernels (e.g. the latest Ubuntu kernels) come with the new 'perf' tools (apt-get install linux-tools) AKA perf_events.

These come with classic sampling profilers (man-page) as well as the awesome timechart!

The important thing is that these tools can be system profiling and not just process profiling - they can show the interaction between threads, processes and the kernel and let you understand the scheduling and I/O dependencies between processes.

Alt text

Transaction isolation levels relation with locks on table

As brb tea says, depends on the database implementation and the algorithm they use: MVCC or Two Phase Locking.

CUBRID (open source RDBMS) explains the idea of this two algorithms:

  • Two-phase locking (2PL)

The first one is when the T2 transaction tries to change the A record, it knows that the T1 transaction has already changed the A record and waits until the T1 transaction is completed because the T2 transaction cannot know whether the T1 transaction will be committed or rolled back. This method is called Two-phase locking (2PL).

  • Multi-version concurrency control (MVCC)

The other one is to allow each of them, T1 and T2 transactions, to have their own changed versions. Even when the T1 transaction has changed the A record from 1 to 2, the T1 transaction leaves the original value 1 as it is and writes that the T1 transaction version of the A record is 2. Then, the following T2 transaction changes the A record from 1 to 3, not from 2 to 4, and writes that the T2 transaction version of the A record is 3.

When the T1 transaction is rolled back, it does not matter if the 2, the T1 transaction version, is not applied to the A record. After that, if the T2 transaction is committed, the 3, the T2 transaction version, will be applied to the A record. If the T1 transaction is committed prior to the T2 transaction, the A record is changed to 2, and then to 3 at the time of committing the T2 transaction. The final database status is identical to the status of executing each transaction independently, without any impact on other transactions. Therefore, it satisfies the ACID property. This method is called Multi-version concurrency control (MVCC).

The MVCC allows concurrent modifications at the cost of increased overhead in memory (because it has to maintain different versions of the same data) and computation (in REPETEABLE_READ level you can't loose updates so it must check the versions of the data, like Hiberate does with Optimistick Locking).

In 2PL Transaction isolation levels control the following:

  • Whether locks are taken when data is read, and what type of locks are requested.

  • How long the read locks are held.

  • Whether a read operation referencing rows modified by another transaction:

    • Block until the exclusive lock on the row is freed.

    • Retrieve the committed version of the row that existed at the time the statement or transaction started.

    • Read the uncommitted data modification.

Choosing a transaction isolation level does not affect the locks that are acquired to protect data modifications. A transaction always gets an exclusive lock on any data it modifies and holds that lock until the transaction completes, regardless of the isolation level set for that transaction. For read operations, transaction isolation levels primarily define the level of protection from the effects of modifications made by other transactions.

A lower isolation level increases the ability of many users to access data at the same time, but increases the number of concurrency effects, such as dirty reads or lost updates, that users might encounter.

Concrete examples of the relation between locks and isolation levels in SQL Server (use 2PL except on READ_COMMITED with READ_COMMITTED_SNAPSHOT=ON)

  • READ_UNCOMMITED: do not issue shared locks to prevent other transactions from modifying data read by the current transaction. READ UNCOMMITTED transactions are also not blocked by exclusive locks that would prevent the current transaction from reading rows that have been modified but not committed by other transactions. [...]


    • If READ_COMMITTED_SNAPSHOT is set to OFF (the default): uses shared locks to prevent other transactions from modifying rows while the current transaction is running a read operation. The shared locks also block the statement from reading rows modified by other transactions until the other transaction is completed. [...] Row locks are released before the next row is processed. [...]
    • If READ_COMMITTED_SNAPSHOT is set to ON, the Database Engine uses row versioning to present each statement with a transactionally consistent snapshot of the data as it existed at the start of the statement. Locks are not used to protect the data from updates by other transactions.
  • REPETEABLE_READ: Shared locks are placed on all data read by each statement in the transaction and are held until the transaction completes.

  • SERIALIZABLE: Range locks are placed in the range of key values that match the search conditions of each statement executed in a transaction. [...] The range locks are held until the transaction completes.

Javascript loading CSV file into an array

This is what I used to use a csv file into an array. Couldn't get the above answers to work, but this worked for me.

$(document).ready(function() {
   "use strict";
        type: "GET",
        url: "../files/icd10List.csv",
        dataType: "text",
        success: function(data) {processData(data);}

function processData(icd10Codes) {
    "use strict";
    var input = $.csv.toArrays(icd10Codes);

Used the jQuery-CSV Plug-in linked above.

Target a css class inside another css class

I use div instead of tables and am able to target classes within the main class, as below:


.main {
    .width: 800px;
    .margin: 0 auto;
    .text-align: center;
.main .table {
    width: 80%;
.main .row {
   / ***something ***/
.main .column {
    font-size: 14px;
    display: inline-block;
.main .left {
    width: 140px;
    margin-right: 5px;
    font-size: 12px;
.main .right {
    width: auto;
    margin-right: 20px;
    color: #fff;
    font-size: 13px;
    font-weight: normal;


<div class="main">
    <div class="table">
        <div class="row">
            <div class="column left">Swing Over Bed</div>
            <div class="column right">650mm</div>
            <div class="column left">Swing In Gap</div>
            <div class="column right">800mm</div>

If you want to style a particular "cell" exclusively you can use another sub-class or the id of the div e.g:

.main #red { color: red; }

<div class="main">
    <div class="table">
        <div class="row">
            <div id="red" class="column left">Swing Over Bed</div>
            <div class="column right">650mm</div>
            <div class="column left">Swing In Gap</div>
            <div class="column right">800mm</div>

Clearing UIWebview cache

After various attempt, only this works well for me (under ios 8):

NSURLCache *cache = [[NSURLCache alloc] initWithMemoryCapacity:1 diskCapacity:1 diskPath:nil];
[NSURLCache setSharedURLCache:cache];

Exception: Can't bind to 'ngFor' since it isn't a known native property

In my case I made the mistake of copying *ng-for= from the docs.

Correct me if I am wrong. But it seems *ng-for= has been changed to *ngFor=

java how to use classes in other package?

It should be like import package_name.Class_Name --> If you want to import a specific class (or)

import package_name.* --> To import all classes in a package

Postgresql Windows, is there a default password?

Try this:

Open PgAdmin -> Files -> Open pgpass.conf

You would get the path of pgpass.conf at the bottom of the window. Go to that location and open this file, you can find your password there.


If the above does not work, you may consider trying this:

 1. edit pg_hba.conf to allow trust authorization temporarily
 2. Reload the config file (pg_ctl reload)
 3. Connect and issue ALTER ROLE / PASSWORD to set the new password
 4. edit pg_hba.conf again and restore the previous settings
 5. Reload the config file again

Docker Networking - nginx: [emerg] host not found in upstream

My Workaround (after much trial and error):

  • In order to get around this issue, I had to get the full name of the 'upstream' Docker container, found by running docker network inspect my-special-docker-network and getting the full name property of the upstream container as such:

    "Containers": {
         "39ad8199184f34585b556d7480dd47de965bc7b38ac03fc0746992f39afac338": {
              "Name": "my_upstream_container_name_1_2478f2b3aca0",
  • Then used this in the NGINX my-network.local.conf file in the location block of the proxy_pass property: (Note the addition of the GUID to the container name):

    location / {
        proxy_pass http://my_upsteam_container_name_1_2478f2b3aca0:3000;

As opposed to the previously working, but now broken:

    location / {
        proxy_pass http://my_upstream_container_name_1:3000

Most likely cause is a recent change to Docker Compose, in their default naming scheme for containers, as listed here.

This seems to be happening for me and my team at work, with latest versions of the Docker nginx image:

  • I've opened issues with them on the docker/compose GitHub here

Matplotlib/pyplot: How to enforce axis range?

To answer my own question, the trick is to turn auto scaling off...

p.axis([0.0,600.0, 10000.0,20000.0])
ax = p.gca()

MySql: is it possible to 'SUM IF' or to 'COUNT IF'?

From MYSQL I solved the problem like this:

SUM(CASE WHEN used = 1 THEN 1 ELSE 0 END) as amount_one,

Hope this helps :D

LINQ: Select where object does not contain items from list

dump this into a more specific collection of just the ids you don't want

var notTheseBarIds = filterBars.Select(fb => fb.BarId);

then try this:

fooSelect = (from f in fooBunch
             where !notTheseBarIds.Contains(f.BarId)
             select f).ToList();

or this:

fooSelect = fooBunch.Where(f => !notTheseBarIds.Contains(f.BarId)).ToList();

Shortcut for changing font size

In visual studio 2019 you can use,


Ctrl + Shift + . To increase

Ctrl + Shift + , To decrease


Go to Tools > Options... > Environment > Fonts and Colors

Check an integer value is Null in c#

Simply you can do this:

    public void CheckNull(int? item)
        if (item != null)
            //Do Something


READ_EXTERNAL_STORAGE permission for Android

Try changing the line contentResolver.query

//change it to the columns you need
String[] columns = new String[]{MediaStore.Audio.AudioColumns.DATA}; 
Cursor cursor = contentResolver.query(uri, columns, null, null, null);

public static final String MEDIA_CONTENT_CONTROL

Not for use by third-party applications due to privacy of media consumption

try to remove the <uses-permission android:name="android.permission.MEDIA_CONTENT_CONTROL"/> first and try again?

"relocation R_X86_64_32S against " linking Error

I also had similar problems when trying to link static compiled fontconfig and expat into a linux shared object:

/opt/rh/devtoolset-7/root/usr/libexec/gcc/x86_64-redhat-linux/7/ld: /3rdparty/fontconfig/lib/linux-x86_64/libfontconfig.a(fccfg.o): relocation R_X86_64_32 against `.rodata.str1.1' can not be used when making a shared object; recompile with -fPIC
/opt/rh/devtoolset-7/root/usr/libexec/gcc/x86_64-redhat-linux/7/ld: /3rdparty/expat/lib/linux-x86_64/libexpat.a(xmlparse.o): relocation R_X86_64_PC32 against symbol `stderr@@GLIBC_2.2.5' can not be used when making a shared object; recompile with -fPIC

This contrary to the fact that I was already passing -fPIC flags though CFLAGS variable, and other compilers/linkers variants (clang/lld) were perfectly working with the same build configuration. It ended up that these dependencies control position-independent code settings through despicable autoconf scripts and need --with-pic switch during build configuration on linux gcc/ld combination, and its lack probably overrides same the setting in CFLAGS. Pass the switch to configure script and the dependencies will be correctly compiled with -fPIC.

Unable to specify the compiler with CMake

I had similar problem as Pietro,

I am on Window 10 and using "Git Bash". I tried to execute >>cmake -G "MinGW Makefiles", but I got the same error as Pietro.

Then, I tried >>cmake -G "MSYS Makefiles", but realized that I need to set my environment correctly.

Make sure set a path to C:\MinGW\msys\1.0\bin and check if you have gcc.exe there. If gcc.exe is not there then you have to run C:/MinGW/bin/mingw-get.exe and install gcc from MSYS.

After that it works fine for me

How to set UTF-8 encoding for a PHP file


<!DOCTYPE html>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<meta name="x" content="xx" />

vs Php:

<?php header('Content-type: text/html; charset=ISO-8859-1'); ?>
<meta name="x" content="xx" />

Easy way to print Perl array? (with a little formatting)

Map can also be used, but sometimes hard to read when you have lots of things going on.

map{ print "element $_\n" }   @array; 

Double quotes within php script echo

Just escape your quotes:

echo "<script>$('#edit_errors').html('<h3><em><font color=\"red\">Please Correct Errors Before Proceeding</font></em></h3>')</script>";

PHP - print all properties of an object

<?php var_dump(obj) ?>


<?php print_r(obj) ?>

These are the same things you use for arrays too.

These will show protected and private properties of objects with PHP 5. Static class members will not be shown according to the manual.

If you want to know the member methods you can use get_class_methods():

$class_methods = get_class_methods('myclass');
// or
$class_methods = get_class_methods(new myclass());
foreach ($class_methods as $method_name) 
    echo "$method_name<br/>";

Related stuff:



get_class() <-- for the name of the instance

Where is android_sdk_root? and how do I set it.?

This is how to change it :

Step 1 :

Open a Terminal / CMD As Administrator (Right-click on cmd and click "Run as Administrator")

Step 2:

type in " set ANDROID_SDK_ROOT=E:\Android\sdk\ " (type it without the quotes and replace "E:\Android\sdk" with your actual sdk file path location - Mine was : C:\Users\YOUR_ACCOUNT\AppData\Local\Android\Sdk

step 3:

Press "Enter" and i noticed nothing happened

Step 4:

Build your app again and it should reflect your file path. For me it doisplayed as :

Preparing Firebase on Android Checking Java JDK and Android SDK versions ANDROID_SDK_ROOT=C:\Users\Kurt\AppData\Local\Android\Sdk (recommended setting) ANDROID_HOME=C:\Users\Kurt\AppData\Local\Android\Sdk (DEPRECATED) Subproject Path: CordovaLib Subproject Path: app

I got that info from this site :

Check it out for more information Have Fun!!

multiple ways of calling parent method in php

Unless I am misunderstanding the question, I would almost always use $this->get_species because the subclass (in this case dog) could overwrite that method since it does extend it. If the class dog doesn't redefine the method then both ways are functionally equivalent but if at some point in the future you decide you want the get_species method in dog should print "dog" then you would have to go back through all the code and change it.

When you use $this it is actually part of the object which you created and so will always be the most up-to-date as well (if the property being used has changed somehow in the lifetime of the object) whereas using the parent class is calling the static class method.

How to generate xsd from wsdl

(WHEN .wsdl is referring to .xsd/schemas using import) If you're using the WMB Tooklit (v8.0.0.4 WMB) then you can find .xsd using following steps :

Create library (optional) > Right Click , New Message Model File > Select SOAP XML > Choose Option 'I already have WSDL for my data' > 'Select file outside workspace' > 'Select the WSDL bindings to Import' (if there are multiple) > Finish.

This will give you the .xsd and .wsdl files in your Workspace (Application Perspective).

Dynamic tabs with user-click chosen components

I'm not cool enough for comments. I fixed the plunker from the accepted answer to work for rc2. Nothing fancy, links to the CDN were just broken is all.

'@angular/core': {
  main: 'bundles/core.umd.js',
  defaultExtension: 'js'
'@angular/compiler': {
  main: 'bundles/compiler.umd.js',
  defaultExtension: 'js'
'@angular/common': {
  main: 'bundles/common.umd.js',
  defaultExtension: 'js'
'@angular/platform-browser-dynamic': {
  main: 'bundles/platform-browser-dynamic.umd.js',
  defaultExtension: 'js'
'@angular/platform-browser': {
  main: 'bundles/platform-browser.umd.js',
  defaultExtension: 'js'

What are good message queue options for nodejs?

Here's a couple of recommendations I can make:

node-amqp: A RabbitMQ client that I have successfully used in combination with Socket.IO to make a real-time multi-player game and chat application amongst other things. Seems reliable enough.

zeromq.node: If you want to go down the non-brokered route this might be worth a look. More work to implement functionality but your more likely to get lower latency and higher throughput.

Get URL of ASP.Net Page in code-behind

Using a js file you can capture the following, that can be used in the codebehind as well:

<script type="text/javascript">
    alert('Server: ' + window.location.hostname);
    alert('Full path: ' + window.location.href);
    alert('Virtual path: ' + window.location.pathname);
    alert('HTTP path: ' + 
        window.location.href.replace(window.location.pathname, ''));    

How do I set up Eclipse/EGit with GitHub?

Make sure your refs for pushing are correct. This tutorial is pretty great, right from the documentation:

You can clone directly from GitHub, you choose where you clone that repository. And when you import that repository to Eclipse, you choose what refspec to push into upstream.

Click on the Git Repository workspace view, and make sure your remote refs are valid. Make sure you are pointing to the right local branch and pushing to the correct remote branch.

How do I unlock a SQLite database?

I found the documentation of the various states of locking in SQLite to be very helpful. Michael, if you can perform reads but can't perform writes to the database, that means that a process has gotten a RESERVED lock on your database but hasn't executed the write yet. If you're using SQLite3, there's a new lock called PENDING where no more processes are allowed to connect but existing connections can sill perform reads, so if this is the issue you should look at that instead.

android: how to change layout on button click?

I think what you're trying to do should be done with multiple Activities. If you're learning Android, understanding Activities is something you're going to have to tackle. Trying to write a whole app with just one Activity will end up being a lot more difficult. Read this article to get yourself started, then you should end up with something more like this:

View.OnClickListener handler = new View.OnClickListener(){
    public void onClick(View v) {

        switch (v.getId()) {

                // doStuff
                startActivity(new Intent(ThisActivity.this, DownloadActivity.class));
                // doStuff
                startActivity(new Intent(ThisActivity.this, AppActivity.class));


ImportError: No module named 'Tkinter'

On CentOS7, to get this working with Python2, I had to do:

yum -y install tkinter

Noting this here because I thought that there would be a pip package, but instead, one needs to actually install an rpm.

How to check if the given string is palindrome?

The interviewer will be looking for some logic on how you will be approaching this problem: Please consider the following java code:

  1. always check if the input string is null
  2. check your base cases.
  3. format your string accordingly (remove anything that is not a character/digit
  4. Most likely they do not want to see if you know the reverse function, and a comparison, but rather if you are able to answer the question using a loop and indexing.
  5. shortcut return as soon as you know your answer and do not waste resources for nothing.

    public static boolean isPalindrome(String s) {

    if (s == null || s.length() == 0 || s.length() == 1)
        return false;
    String ss = s.toLowerCase().replaceAll("/[^a-z]/", "");
    for (int i = 0; i < ss.length()/2; i++) 
        if (ss.charAt(i) != ss.charAt(ss.length() - 1 - i))
            return false;
    return true;


Automatically running a batch file as an administrator

The complete solution I found that worked was:

@echo off
cd /D "%~dp0"
if not "%1"=="am_admin" (powershell start -verb runas '%0' am_admin & exit /b)
"Put your command here"

credit for:

Append values to query string

The provided answers have issues with relative Url's, such as "/some/path/" This is a limitation of the Uri and UriBuilder class, which is rather hard to understand, since I don't see any reason why relative urls would be problematic when it comes to query manipulation.

Here is a workaround that works for both absolute and relative paths, written and tested in .NET 4:

(small note: this should also work in .NET 4.5, you will only have to change propInfo.GetValue(values, null) to propInfo.GetValue(values))

  public static class UriExtensions{
    /// <summary>
    ///     Adds query string value to an existing url, both absolute and relative URI's are supported.
    /// </summary>
    /// <example>
    /// <code>
    ///     // returns ";param2=val2&amp;param3=val3"
    ///     new Uri("").ExtendQuery(new Dictionary&lt;string, string&gt; { { "param2", "val2" }, { "param3", "val3" } }); 
    ///     // returns "/test?param1=val1&amp;param2=val2&amp;param3=val3"
    ///     new Uri("/test?param1=val1").ExtendQuery(new Dictionary&lt;string, string&gt; { { "param2", "val2" }, { "param3", "val3" } }); 
    /// </code>
    /// </example>
    /// <param name="uri"></param>
    /// <param name="values"></param>
    /// <returns></returns>
    public static Uri ExtendQuery(this Uri uri, IDictionary<string, string> values) {
      var baseUrl = uri.ToString();
      var queryString = string.Empty;
      if (baseUrl.Contains("?")) {
        var urlSplit = baseUrl.Split('?');
        baseUrl = urlSplit[0];
        queryString = urlSplit.Length > 1 ? urlSplit[1] : string.Empty;

      NameValueCollection queryCollection = HttpUtility.ParseQueryString(queryString);
      foreach (var kvp in values ?? new Dictionary<string, string>()) {
        queryCollection[kvp.Key] = kvp.Value;
      var uriKind = uri.IsAbsoluteUri ? UriKind.Absolute : UriKind.Relative;
      return queryCollection.Count == 0 
        ? new Uri(baseUrl, uriKind) 
        : new Uri(string.Format("{0}?{1}", baseUrl, queryCollection), uriKind);

    /// <summary>
    ///     Adds query string value to an existing url, both absolute and relative URI's are supported.
    /// </summary>
    /// <example>
    /// <code>
    ///     // returns ";param2=val2&amp;param3=val3"
    ///     new Uri("").ExtendQuery(new { param2 = "val2", param3 = "val3" }); 
    ///     // returns "/test?param1=val1&amp;param2=val2&amp;param3=val3"
    ///     new Uri("/test?param1=val1").ExtendQuery(new { param2 = "val2", param3 = "val3" }); 
    /// </code>
    /// </example>
    /// <param name="uri"></param>
    /// <param name="values"></param>
    /// <returns></returns>
    public static Uri ExtendQuery(this Uri uri, object values) {
      return ExtendQuery(uri, values.GetType().GetProperties().ToDictionary
          propInfo => propInfo.Name,
          propInfo => { var value = propInfo.GetValue(values, null); return value != null ? value.ToString() : null; }

And here is a suite of unit tests to test the behavior:

  public class UriExtensionsTests {
    public void Add_to_query_string_dictionary_when_url_contains_no_query_string_and_values_is_empty_should_return_url_without_changing_it() {
      Uri url = new Uri("");
      var values = new Dictionary<string, string>();
      var result = url.ExtendQuery(values);
      Assert.That(result, Is.EqualTo(new Uri("")));

    public void Add_to_query_string_dictionary_when_url_contains_hash_and_query_string_values_are_empty_should_return_url_without_changing_it() {
      Uri url = new Uri("");
      var values = new Dictionary<string, string>();
      var result = url.ExtendQuery(values);
      Assert.That(result, Is.EqualTo(new Uri("")));

    public void Add_to_query_string_dictionary_when_url_contains_no_query_string_should_add_values() {
      Uri url = new Uri("");
      var values = new Dictionary<string, string> { { "param1", "val1" }, { "param2", "val2" } };
      var result = url.ExtendQuery(values);
      Assert.That(result, Is.EqualTo(new Uri("")));

    public void Add_to_query_string_dictionary_when_url_contains_hash_and_no_query_string_should_add_values() {
      Uri url = new Uri("");
      var values = new Dictionary<string, string> { { "param1", "val1" }, { "param2", "val2" } };
      var result = url.ExtendQuery(values);
      Assert.That(result, Is.EqualTo(new Uri("")));

    public void Add_to_query_string_dictionary_when_url_contains_query_string_should_add_values_and_keep_original_query_string() {
      Uri url = new Uri("");
      var values = new Dictionary<string, string> { { "param2", "val2" } };
      var result = url.ExtendQuery(values);
      Assert.That(result, Is.EqualTo(new Uri("")));

    public void Add_to_query_string_dictionary_when_url_is_relative_contains_no_query_string_should_add_values() {
      Uri url = new Uri("/test", UriKind.Relative);
      var values = new Dictionary<string, string> { { "param1", "val1" }, { "param2", "val2" } };
      var result = url.ExtendQuery(values);
      Assert.That(result, Is.EqualTo(new Uri("/test?param1=val1&param2=val2", UriKind.Relative)));

    public void Add_to_query_string_dictionary_when_url_is_relative_and_contains_query_string_should_add_values_and_keep_original_query_string() {
      Uri url = new Uri("/test?param1=val1", UriKind.Relative);
      var values = new Dictionary<string, string> { { "param2", "val2" } };
      var result = url.ExtendQuery(values);
      Assert.That(result, Is.EqualTo(new Uri("/test?param1=val1&param2=val2", UriKind.Relative)));

    public void Add_to_query_string_dictionary_when_url_is_relative_and_contains_query_string_with_existing_value_should_add_new_values_and_update_existing_ones() {
      Uri url = new Uri("/test?param1=val1", UriKind.Relative);
      var values = new Dictionary<string, string> { { "param1", "new-value" }, { "param2", "val2" } };
      var result = url.ExtendQuery(values);
      Assert.That(result, Is.EqualTo(new Uri("/test?param1=new-value&param2=val2", UriKind.Relative)));

    public void Add_to_query_string_object_when_url_contains_no_query_string_should_add_values() {
      Uri url = new Uri("");
      var values = new { param1 = "val1", param2 = "val2" };
      var result = url.ExtendQuery(values);
      Assert.That(result, Is.EqualTo(new Uri("")));

    public void Add_to_query_string_object_when_url_contains_query_string_should_add_values_and_keep_original_query_string() {
      Uri url = new Uri("");
      var values = new { param2 = "val2" };
      var result = url.ExtendQuery(values);
      Assert.That(result, Is.EqualTo(new Uri("")));

    public void Add_to_query_string_object_when_url_is_relative_contains_no_query_string_should_add_values() {
      Uri url = new Uri("/test", UriKind.Relative);
      var values = new { param1 = "val1", param2 = "val2" };
      var result = url.ExtendQuery(values);
      Assert.That(result, Is.EqualTo(new Uri("/test?param1=val1&param2=val2", UriKind.Relative)));

    public void Add_to_query_string_object_when_url_is_relative_and_contains_query_string_should_add_values_and_keep_original_query_string() {
      Uri url = new Uri("/test?param1=val1", UriKind.Relative);
      var values = new { param2 = "val2" };
      var result = url.ExtendQuery(values);
      Assert.That(result, Is.EqualTo(new Uri("/test?param1=val1&param2=val2", UriKind.Relative)));

    public void Add_to_query_string_object_when_url_is_relative_and_contains_query_string_with_existing_value_should_add_new_values_and_update_existing_ones() {
      Uri url = new Uri("/test?param1=val1", UriKind.Relative);
      var values = new { param1 = "new-value", param2 = "val2" };
      var result = url.ExtendQuery(values);
      Assert.That(result, Is.EqualTo(new Uri("/test?param1=new-value&param2=val2", UriKind.Relative)));

How to add a char/int to an char array in C?

In C/C++ a string is an array of char terminated with a NULL byte ('\0');

  1. Your string str has not been initialized.
  2. You must concatenate strings and you are trying to concatenate a single char (without the null byte so it's not a string) to a string.

The code should look like this:

char str[1024] = "Hello World"; //this will add all characters and a NULL byte to the array
char tmp[2] = "."; //this is a string with the dot 
strcat(str, tmp);  //here you concatenate the two strings

Note that you can assign a string literal to an array only during its declaration.
For example the following code is not permitted:

char str[1024];
str = "Hello World"; //FORBIDDEN

and should be replaced with

char str[1024];
strcpy(str, "Hello World"); //here you copy "Hello World" inside the src array 

How to replace master branch in Git, entirely, from another branch?

What about using git branch -m to rename the master branch to another one, then rename seotweaks branch to master? Something like this:

git branch -m master old-master
git branch -m seotweaks master
git push -f origin master

This might remove commits in origin master, please check your origin master before running git push -f origin master.

What is an efficient way to implement a singleton pattern in Java?

This is how to implement a simple singleton:

public class Singleton {
    // It must be static and final to prevent later modification
    private static final Singleton INSTANCE = new Singleton();
    /** The constructor must be private to prevent external instantiation */
    private Singleton(){}
    /** The public static method allowing to get the instance */
    public static Singleton getInstance() {
        return INSTANCE;

This is how to properly lazy create your singleton:

public class Singleton {
    // The constructor must be private to prevent external instantiation
    private Singleton(){}
    /** The public static method allowing to get the instance */
    public static Singleton getInstance() {
        return SingletonHolder.INSTANCE;
     * The static inner class responsible for creating your instance only on demand,
     * because the static fields of a class are only initialized when the class
     * is explicitly called and a class initialization is synchronized such that only
     * one thread can perform it, this rule is also applicable to inner static class
     * So here INSTANCE will be created only when SingletonHolder.INSTANCE
     * will be called
    private static class SingletonHolder {
        private static final Singleton INSTANCE = new Singleton();

warning: assignment makes integer from pointer without a cast

When you write the statement

*src = "anotherstring";

the compiler sees the constant string "abcdefghijklmnop" like an array. Imagine you had written the following code instead:

char otherstring[14] = "anotherstring";
*src = otherstring;

Now, it's a bit clearer what is going on. The left-hand side, *src, refers to a char (since src is of type pointer-to-char) whereas the right-hand side, otherstring, refers to a pointer.

This isn't strictly forbidden because you may want to store the address that a pointer points to. However, an explicit cast is normally used in that case (which isn't too common of a case). The compiler is throwing up a red flag because your code is likely not doing what you think it is.

It appears to me that you are trying to assign a string. Strings in C aren't data types like they are in C++ and are instead implemented with char arrays. You can't directly assign values to a string like you are trying to do. Instead, you need to use functions like strncpy and friends from <string.h> and use char arrays instead of char pointers. If you merely want the pointer to point to a different static string, then drop the *.

C default arguments

We can create functions which use named parameters (only) for default values. This is a continuation of bk.'s answer.

#include <stdio.h>                                                               

struct range { int from; int to; int step; };
#define range(...) range((struct range){.from=1,.to=10,.step=1, __VA_ARGS__})   

/* use parentheses to avoid macro subst */             
void (range)(struct range r) {                                                     
    for (int i = r.from; i <=; i += r.step)                                 
        printf("%d ", i);                                                        

int main() {                                                                     
    range(.from=2, .to=4);                                                      

The C99 standard defines that later names in the initialization override previous items. We can also have some standard positional parameters as well, just change the macro and function signature accordingly. The default value parameters can only be used in named parameter style.

Program output:

1 2 3 4 5 6 7 8 9 10 
2 3 4 
1 3 5 7 9

Excel VBA - Pass a Row of Cell Values to an Array and then Paste that Array to a Relative Reference of Cells

Since you are copying tha same data to all rows, you don't actually need to loop at all. Try this:

    Dim Number_of_Sims As Long
    Dim rng As Range

    Application.Calculation = xlCalculationManual
    Application.ScreenUpdating = False
    Number_of_Sims = 100000

    Set rng = Range("C4:G4")
    rng.Offset(1, 0).Resize(Number_of_Sims) = rng.Value

    Application.Calculation = xlCalculationAutomatic
    Application.ScreenUpdating = True
End Sub

How to merge a Series and DataFrame

You can easily set a pandas.DataFrame column to a constant. This constant can be an int such as in your example. If the column you specify isn't in the df, then pandas will create a new column with the name you specify. So after your dataframe is constructed, (from your question):

df = pd.DataFrame({'a':[np.nan, 2, 3], 'b':[4, 5, 6]}, index=[3, 5, 6])

You can just run:

df['s1'], df['s2'] = 5, 6

You could write a loop or comprehension to make it do this for all the elements in a list of tuples, or keys and values in a dictionary depending on how you have your real data stored.

Start thread with member function

@hop5 and @RnMss suggested to use C++11 lambdas, but if you deal with pointers, you can use them directly:

#include <thread>
#include <iostream>

class CFoo {
    int m_i = 0;
    void bar() {

int main() {
  CFoo foo;
  std::thread t1(&CFoo::bar, &foo);
  std::thread t2(&CFoo::bar, &foo);
  std::cout << foo.m_i << std::endl;
  return 0;



Rewritten sample from this answer would be then:

#include <thread>
#include <iostream>

class Wrapper {
      void member1() {
          std::cout << "i am member1" << std::endl;
      void member2(const char *arg1, unsigned arg2) {
          std::cout << "i am member2 and my first arg is (" << arg1 << ") and second arg is (" << arg2 << ")" << std::endl;
      std::thread member1Thread() {
          return std::thread(&Wrapper::member1, this);
      std::thread member2Thread(const char *arg1, unsigned arg2) {
          return std::thread(&Wrapper::member2, this, arg1, arg2);

int main() {
  Wrapper *w = new Wrapper();
  std::thread tw1 = w->member1Thread();
  std::thread tw2 = w->member2Thread("hello", 100);
  return 0;

angular-cli server - how to specify default port

In Angular 2 [email protected],

To run a new project on the different port, one way is to specify the port while you run ng serve command.

ng serve --port 4201

or the other way, you can edit your package.json file scripts part and attached the port to your start variable like I mentioned below and then simply run "npm start"

 "scripts": {

    "ng": "ng",
    "start": "ng serve --port 4201",
    ... : ...,
    ... : ....

this way is much better where you don't need to define port explicitly every time.

Where does SVN client store user authentication data?

It sounds like you are doing everything exactly as the client credential section of the Subversion book suggests. The only thing I can think of is that the server isn't asking for the username and password because is getting it from somewhere else.

How to timeout a thread

In the solution given by BalusC, the main thread will stay blocked for the timeout period. If you have a thread pool with more than one thread, you will need the same number of additional thread that will be using Future.get(long timeout,TimeUnit unit) blocking call to wait and close the thread if it exceeds the timeout period.

A generic solution to this problem is to create a ThreadPoolExecutor Decorator that can add the timeout functionality. This Decorator class should create as many threads as ThreadPoolExecutor has, and all these threads should be used only to wait and close the ThreadPoolExecutor.

The generic class should be implemented like below:

import java.util.List;
import java.util.concurrent.*;

public class TimeoutThreadPoolDecorator extends ThreadPoolExecutor {

    private final ThreadPoolExecutor commandThreadpool;
    private final long timeout;
    private final TimeUnit unit;

    public TimeoutThreadPoolDecorator(ThreadPoolExecutor threadpool,
                                      long timeout,
                                      TimeUnit unit ){
        super(  threadpool.getCorePoolSize(),

        this.commandThreadpool = threadpool;

    public void execute(Runnable command) {
        super.execute(() -> {
            Future<?> future = commandThreadpool.submit(command);
            try {
                future.get(timeout, unit);
            } catch (InterruptedException e) {
            } catch (ExecutionException | TimeoutException e) {
                throw new RejectedExecutionException(e);
            } finally {

    public void setCorePoolSize(int corePoolSize) {

    public void setThreadFactory(ThreadFactory threadFactory) {

    public void setMaximumPoolSize(int maximumPoolSize) {

    public void setKeepAliveTime(long time, TimeUnit unit) {
        super.setKeepAliveTime(time, unit);
        commandThreadpool.setKeepAliveTime(time, unit);

    public void setRejectedExecutionHandler(RejectedExecutionHandler handler) {

    public List<Runnable> shutdownNow() {
        List<Runnable> taskList = super.shutdownNow();
        return taskList;

    public void shutdown() {

The above decorator can be used as below:

import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class Main {

    public static void main(String[] args){

        long timeout = 2000;

        ThreadPoolExecutor threadPool = new ThreadPoolExecutor(3, 10, 0, TimeUnit.MILLISECONDS, new SynchronousQueue<>(true));

        threadPool = new TimeoutThreadPoolDecorator( threadPool ,




    private static Runnable command(int i) {

        return () -> {
            System.out.println("Running Thread:"+Thread.currentThread().getName());
            System.out.println("Starting command with sleep:"+i);
            try {
            } catch (InterruptedException e) {
                System.out.println("Thread "+Thread.currentThread().getName()+" with sleep of "+i+" is Interrupted!!!");
            System.out.println("Completing Thread "+Thread.currentThread().getName()+" after sleep of "+i);


parse html string with jquery



        url: uri+'?js',  
        success: function(data) {  
                var imgAttr = $("img", data).attr('src'); 
                var htmlCode = $(data).html();

This should load the whole html block from data into #fullHtmlOutput and the src of the image into #imgSrc.

How to switch a user per task or set of tasks?

You can specify become_method to override the default method set in ansible.cfg (if any), and which can be set to one of sudo, su, pbrun, pfexec, doas, dzdo, ksu.

- name: I am confused
  command: 'whoami'
  become: true
  become_method: su
  become_user: some_user
  register: myidentity

- name: my secret identity
    msg: '{{ myidentity.stdout }}'

Should display

TASK [my-task : my secret identity] ************************************************************
ok: [my_ansible_server] => {
    "msg": "some_user"

Microsoft Excel mangles Diacritics in .csv files?

Note that including the UTF-8 BOM is not necessarily a good idea - Mac versions of Excel ignore it and will actually display the BOM as ASCII… three nasty characters at the start of the first field in your spreadsheet…

Implement Stack using Two Queues

Version A (efficient push):

  • push:
    • enqueue in queue1
  • pop:
    • while size of queue1 is bigger than 1, pipe dequeued items from queue1 into queue2
    • dequeue and return the last item of queue1, then switch the names of queue1 and queue2

Version B (efficient pop):

  • push:
    • enqueue in queue2
    • enqueue all items of queue1 in queue2, then switch the names of queue1 and queue2
  • pop:
    • deqeue from queue1

How to go to a URL using jQuery?

why not using?


<!DOCTYPE html>_x000D_
    function goToURL() {_x000D_
      location.href = '';_x000D_
  <a href="javascript:void(0)" onclick="goToURL(); return false;">Go To URL</a>_x000D_

Add table row in jQuery


You can append it to the tbody using the appendTo method like this:

$(() => {
   $("<tr><td>my data</td><td>more data</td></tr>").appendTo("tbody");

You'll probably want to use the latest JQuery and ECMAScript. Then you can use a back-end language to add your data to the table. You can also wrap it in a variable like so:

$(() => {
  var t_data = $('<tr><td>my data</td><td>more data</td></tr>');

How to change a nullable column to not nullable in a Rails migration?

If you do it in a migration then you could probably do it like this:

# Make sure no null value exist
MyModel.where(date_column: nil).update_all(date_column:

# Change the column to not allow null
change_column :my_models, :date_column, :datetime, null: false

Last executed queries for a specific database

This works for me to find queries on any database in the instance. I'm sysadmin on the instance (check your privileges):

SELECT deqs.last_execution_time AS [Time], dest.text AS [Query], dest.*
FROM sys.dm_exec_query_stats AS deqs
CROSS APPLY sys.dm_exec_sql_text(deqs.sql_handle) AS dest
WHERE dest.dbid = DB_ID('msdb')
ORDER BY deqs.last_execution_time DESC

This is the same answer that Aaron Bertrand provided but it wasn't placed in an answer.

Execute a file with arguments in Python shell

This works:"python arg1 arg2", shell=True)

How to make a simple modal pop up form using jquery and html?

I came across this question when I was trying similar things.

A very nice and simple sample is presented at w3schools website.

<!DOCTYPE html>_x000D_
<html lang="en">_x000D_
  <title>Bootstrap Example</title>_x000D_
  <meta charset="utf-8">_x000D_
  <meta name="viewport" content="width=device-width, initial-scale=1">_x000D_
  <link rel="stylesheet" href="">_x000D_
  <script src=""></script>_x000D_
  <script src=""></script>_x000D_
<div class="container">_x000D_
  <h2>Modal Example</h2>_x000D_
  <!-- Trigger the modal with a button -->_x000D_
  <button type="button" class="btn btn-info btn-lg" data-toggle="modal" data-target="#myModal">Open Modal</button>_x000D_
  <!-- Modal -->_x000D_
  <div class="modal fade" id="myModal" role="dialog">_x000D_
    <div class="modal-dialog">_x000D_
      <!-- Modal content-->_x000D_
      <div class="modal-content">_x000D_
        <div class="modal-header">_x000D_
          <button type="button" class="close" data-dismiss="modal">&times;</button>_x000D_
          <h4 class="modal-title">Modal Header</h4>_x000D_
        <div class="modal-body">_x000D_
          <p>Some text in the modal.</p>_x000D_
        <div class="modal-footer">_x000D_
          <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>_x000D_

Create a day-of-week column in a Pandas dataframe using Python

Using dt.weekday_name is deprecated since pandas 0.23.0, instead, use dt.day_name():

df = pd.DataFrame({'my_dates':['2015-01-01','2015-01-02','2015-01-03'],'myvals':[1,2,3]})
df['my_dates'] = pd.to_datetime(df['my_dates'])


0    Thursday
1      Friday
2    Saturday
Name: my_dates, dtype: object

How to align LinearLayout at the center of its parent?

add layout_gravity="center" or "center_horizontal" to the parent layout.

On a side note, your LinearLayout inside your TableRow seems un-necessary, as a TableRow is already an horizontal LinearLayout.

How do I navigate to a parent route from a child route?

My solution is:

const urlSplit = this._router.url.split('/');
this._router.navigate([urlSplit.splice(0, urlSplit.length - 1).join('/')], { relativeTo: this._route.parent });

And the Router injection:

private readonly _router: Router

psycopg2: insert multiple rows with one query

If you're using SQLAlchemy, you don't need to mess with hand-crafting the string because SQLAlchemy supports generating a multi-row VALUES clause for a single INSERT statement:

rows = []
for i, name in enumerate(rawdata):
    row = {
        'id': i,
        'name': name,
        'valid': True,
if len(rows) > 0:  # INSERT fails if no rows
    insert_query = SQLAlchemyModelName.__table__.insert().values(rows)

Combine two (or more) PDF's

I've done this with PDFBox. I suppose it works similarly to iTextSharp.

Python - Get Yesterday's date as a string in YYYY-MM-DD format

>>> import datetime

Mocking a function to raise an Exception to test an except block

Your mock is raising the exception just fine, but the error.resp.status value is missing. Rather than use return_value, just tell Mock that status is an attribute:

barMock.side_effect = HttpError(mock.Mock(status=404), 'not found')

Additional keyword arguments to Mock() are set as attributes on the resulting object.

I put your foo and bar definitions in a my_tests module, added in the HttpError class so I could use it too, and your test then can be ran to success:

>>> from my_tests import foo, HttpError
>>> import mock
>>> with mock.patch('') as barMock:
...     barMock.side_effect = HttpError(mock.Mock(status=404), 'not found')
...     result =
404 - 
>>> result is None

You can even see the print '404 - %s' % error.message line run, but I think you wanted to use error.content there instead; that's the attribute HttpError() sets from the second argument, at any rate.

Print PDF directly from JavaScript

Based on comments below, it no longer works in modern browsers
This question demonstrates an approach that might be helpful to you: Silent print an embedded PDF

It uses the <embed> tag to embed the PDF in the document:

    height="100%" />

Then you call the .print() method on the element in Javascript when the PDF is loaded:

function printDocument(documentId) {
    var doc = document.getElementById(documentId);

    //Wait until PDF is ready to print    
    if (typeof doc.print === 'undefined') {    
        setTimeout(function(){printDocument(documentId);}, 1000);
    } else {

You could place the embed in a hidden iframe and print it from there, giving you a seamless experience.

How can I use/create dynamic template to compile dynamic Component with Angular 2.0?

Following up on Radmin's excellent answer, there is a little tweak needed for everyone who is using angular-cli version 1.0.0-beta.22 and above.

COMPILER_PROVIDERScan no longer be imported (for details see angular-cli GitHub).

So the workaround there is to not use COMPILER_PROVIDERS and JitCompiler in the providers section at all, but use JitCompilerFactory from '@angular/compiler' instead like this inside the type builder class:

private compiler: Compiler = new JitCompilerFactory([{useDebug: false, useJit: true}]).createCompiler();

As you can see, it is not injectable and thus has no dependencies with the DI. This solution should also work for projects not using angular-cli.

Uncaught TypeError : cannot read property 'replace' of undefined In Grid

In my case, I was using a View that I´ve converted to partial view and I forgot to remove the template from "@section scripts". Removing the section block, solved my problem. This is because the sections aren´t rendered in partial views.

How can I add an image file into json object?

You're only adding the File object to the JSON object. The File object only contains meta information about the file: Path, name and so on.

You must load the image and read the bytes from it. Then put these bytes into the JSON object.

Linux: is there a read or recv from socket with timeout?

// works also after bind operation for WINDOWS

DWORD timeout = timeout_in_seconds * 1000;
setsockopt(socket, SOL_SOCKET, SO_RCVTIMEO, (const char*)&timeout, sizeof timeout); cannot open shared object file

After checking to which package does the belongs ( you should try to install zlib1g:

sudo apt-get install zlib1g

As pointed by @E-rich, it may be required to add a :i386 suffix to the package name for the package manager correctly identify it:

sudo apt-get install zlib1g:i386

EDIT (for CentOS or other distro that makes use of yum):

If someone using CentOS (or any other distro that makes use of yum) that may end up reading this question, @syslogic proposed the following solution in the comments:

yum install zlib.i686

or, for 32-bit binaries:

yum install zlib.i386

What is the difference between char array and char pointer in C?

For cases like this, the effect is the same: You end up passing the address of the first character in a string of characters.

The declarations are obviously not the same though.

The following sets aside memory for a string and also a character pointer, and then initializes the pointer to point to the first character in the string.

char *p = "hello";

While the following sets aside memory just for the string. So it can actually use less memory.

char p[10] = "hello";

How do I set Tomcat Manager Application User Name and Password for NetBeans?

Go to apache-tomcat\conf folder add these lines in

tomcat-users.xml file

<role rolename="manager-gui"/>
<user username="admin" password="admin" roles="manager-gui"/>

and restart server

Types in MySQL: BigInt(20) vs Int(20)


  • INT is a four-byte signed integer.

  • BIGINT is an eight-byte signed integer.

They each accept no more and no fewer values than can be stored in their respective number of bytes. That means 232 values in an INT and 264 values in a BIGINT.

The 20 in INT(20) and BIGINT(20) means almost nothing. It's a hint for display width. It has nothing to do with storage, nor the range of values that column will accept.

Practically, it affects only the ZEROFILL option:

INSERT INTO foo (bar) VALUES (1234);
SELECT bar from foo;

| bar                  |
| 00000000000000001234 |

It's a common source of confusion for MySQL users to see INT(20) and assume it's a size limit, something analogous to CHAR(20). This is not the case.

Remove the last chars of the Java String variable

I am surprised to see that all the other answers (as of Sep 8, 2013) either involve counting the number of characters in the substring ".null" or throw a StringIndexOutOfBoundsException if the substring is not found. Or both :(

I suggest the following:

public class Main {

    public static void main(String[] args) {

        String path = "file.txt";
        String extension = ".doc";

        int position = path.lastIndexOf(extension);

        if (position!=-1)
            path = path.substring(0, position);
            System.out.println("Extension: "+extension+" not found");

        System.out.println("Result: "+path);


If the substring is not found, nothing happens, as there is nothing to cut off. You won't get the StringIndexOutOfBoundsException. Also, you don't have to count the characters yourself in the substring.

Use nginx to serve static files from subdirectories of a given directory

It should work, however says:

When location matches the last part of the directive’s value: it is better to use the root directive instead:

which would yield:

server {
  listen        8080;
  error_log     /home/www-data/logs/nginx_www.error.log;
  error_page    404    /404.html;

  location /public/doc/ {
    autoindex on;
    root  /home/www-data/mysite;

  location = /404.html {
    root /home/www-data/mysite/static/html;

How to find the process id of a running Java process on Windows? And how to kill the process alone?

This is specific to Windows. I was facing the same issue where I have to kill one specific java program using taskkill. When I run the java program, tasklist was showing the same program with Image name set as java.exe. But killing it using taskkill /F java.exe will stop all other java applications other than intended one which is not required.

So I run the same java program using:

start "MyProgramName" java java-program..

Here start command will open a new window and run the java program with window's title set to MyProgramName.

Now to kill this java-program use the following taskkill command:

taskkill /fi "MyProgramName"

Your Java program will be killed only. Rest will be unaffected.

How do I make a fully statically linked .exe with Visual Studio Express 2005?

My experience in Visual Studio 2010 is that there are two changes needed so as to not need DLL's. From the project property page (right click on the project name in the Solution Explorer window):

  1. Under Configuration Properties --> General, change the "Use of MFC" field to "Use MFC in a Static Library".

  2. Under Configuration Properties --> C/C++ --> Code Generation, change the "Runtime Library" field to "Multi-Threaded (/MT)"

Not sure why both were needed. I used this to remove a dependency on glut32.dll.

Added later: When making these changes to the configurations, you should make them to "All Configurations" --- you can select this at the top of the Properties window. If you make the change to just the Debug configuration, it won't apply to the Release configuration, and vice-versa.

Align HTML input fields by :

Working JS Fiddle


      <label>Name:</label><input type="text">
      <label>Email Address:</label><input type = "text">
      <label>Description of the input value:</label><input type="text">


    display: inline-block;
    float: left;
    clear: left;
    width: 250px;
    text-align: right;
input {
  display: inline-block;
  float: left;

Java 8 Stream API to find Unique Object matching a property value

findAny & orElse

By using findAny() and orElse():

Person matchingObject =
filter(p ->"testemail")).

Stops looking after finding an occurrence.


Optional<T> findAny()

Returns an Optional describing some element of the stream, or an empty Optional if the stream is empty. This is a short-circuiting terminal operation. The behavior of this operation is explicitly nondeterministic; it is free to select any element in the stream. This is to allow for maximal performance in parallel operations; the cost is that multiple invocations on the same source may not return the same result. (If a stable result is desired, use findFirst() instead.)

Adding open/closed icon to Twitter Bootstrap collapsibles (accordions)

Here is my solution which is further refined from one posted by @john-magnolia and solves some of its issues

 * Toggle on/off arrow for Twitter Bootstrap collapsibles.
 * Multi-collapsible-friendly; supports several collapsibles in the same group, on the same page.
function animateCollapsibles() {

    $('.collapse').on('show', function() {
        var $t = $(this);
        var header = $("a[href='#" + $t.attr("id") + "']");
    }).on('hide', function(){
        var $t = $(this);
        var header = $("a[href='#" + $t.attr("id") + "']");

And here is the example markup:

<div class="accordion" id="accordion-send">
    <div class="accordion-group">
        <div class="accordion-heading">
            <a class="accordion-toggle" data-toggle="collapse" data-parent="#accordion-send" href="#collapse-refund">
                <i class="icon icon-chevron-right"></i> Send notice
        <div id="collapse-refund" class="accordion-body collapse">
            <div class="accordion-inner">
                <p>Lorem ipsum Toholampi city</p>

How can I get the CheckBoxList selected values, what I have doesn't seem to work C#.NET/VisualWebPart

Try something like this:

foreach (ListItem listItem in YrChkBox.Items)
    if (listItem.Selected)
       //do some work 
      //do something else 

How to trap on UIViewAlertForUnsatisfiableConstraints?

Followed Stephen's advice and tried to debug the code and whoa! it worked. The answer lies in the debug message itself.

Will attempt to recover by breaking constraint NSLayoutConstraint:0x191f0920 H:[MPKnockoutButton:0x17a876b0]-(34)-[MPDetailSlider:0x17a8bc50](LTR)>

The line above tells you that the runtime worked by removing this constraint. May be you don't need Horizontal Spacing on your button (MPKnockoutButton). Once you clear this constraint, it won't complain at runtime & you would get the desired behaviour.

Difference between "this" and"super" keywords in Java

When writing code you generally don't want to repeat yourself. If you have an class that can be constructed with various numbers of parameters a common solution to avoid repeating yourself is to simply call another constructor with defaults in the missing arguments. There is only one annoying restriction to this - it must be the first line of the declared constructor. Example:

   this(default1, default2);

MyClass(arg1, arg2)
   validate arguments, etc...
   note that your validation logic is only written once now

As for the super() constructor, again unlike super.method() access it must be the first line of your constructor. After that it is very much like the this() constructors, DRY (Don't Repeat Yourself), if the class you extend has a constructor that does some of what you want then use it and then continue with constructing your object, example:

YourClass extends MyClass
   YourClass(arg1, arg2, arg3)
      super(arg1, arg2) // calls MyClass(arg1, arg2)
      validate and process arg3...

Additional information:

Even though you don't see it, the default no argument constructor always calls super() first. Example:


is equivalent to


I see that many have mentioned using the this and super keywords on methods and variables - all good. Just remember that constructors have unique restrictions on their usage, most notable is that they must be the very first instruction of the declared constructor and you can only use one.

What ports does RabbitMQ use?

What ports is RabbitMQ using?

Default: 5672, the manual has the answer. It's defined in the RABBITMQ_NODE_PORT variable.

The number might be differently if changed by someone in the rabbitmq configuration file:

vi /etc/rabbitmq/rabbitmq-env.conf

Ask the computer to tell you:

sudo nmap -p 1-65535 localhost

Starting Nmap 5.51 ( ) at 2014-09-19 13:50 EDT
Nmap scan report for localhost (
Host is up (0.00041s latency).
443/tcp   open          https
5672/tcp  open          amqp
15672/tcp open  unknown
35102/tcp open  unknown
59440/tcp open  unknown

Oh look, 5672, and 15672

Use netstat:

netstat -lntu
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State
tcp        0      0     *                   LISTEN
tcp        0      0     *                   LISTEN
tcp        0      0 :::5672                     :::*                        LISTEN

Oh look 5672.

use lsof:

eric@dev ~$ sudo lsof -i | grep beam
beam.smp  21216    rabbitmq   17u  IPv4 33148214      0t0  TCP *:55672 (LISTEN)
beam.smp  21216    rabbitmq   18u  IPv4 33148219      0t0  TCP *:15672 (LISTEN)

use nmap from a different machine, find out if 5672 is open:

sudo nmap -p 5672
Starting Nmap 5.51 ( ) at 2014-09-19 13:19 EDT
Nmap scan report for
Host is up (0.00011s latency).
5672/tcp open  amqp
MAC Address: 0A:40:0E:8C:75:6C (Unknown)    
Nmap done: 1 IP address (1 host up) scanned in 0.13 seconds

Try to connect to a port manually with telnet, 5671 is CLOSED:

telnet localhost 5671
telnet: connect to address Connection refused

Try to connect to a port manually with telnet, 5672 is OPEN:

telnet localhost 5672
Connected to localhost.
Escape character is '^]'.

Check your firewall:

sudo cat /etc/sysconfig/iptables  

It should tell you what ports are made open:

-A INPUT -p tcp -m tcp --dport 5672 -j ACCEPT

Reapply your firewall:

sudo service iptables restart
iptables: Setting chains to policy ACCEPT: filter          [  OK  ]
iptables: Flushing firewall rules:                         [  OK  ]
iptables: Unloading modules:                               [  OK  ]
iptables: Applying firewall rules:                         [  OK  ]

T-SQL How to create tables dynamically in stored procedures?

You can write the below code:-

create procedure spCreateTable
       create table testtb(Name varchar(20))

execute it as:-

exec spCreateTable

Create a pointer to two-dimensional array

You can always avoid fiddling around with the compiler by declaring the array as linear and doing the (row,col) to array index calculation by yourself.

static uint8_t l_matrix[200];

void test(int row, int col, uint8_t val)


   uint8_t* matrix_ptr = l_matrix;
   matrix_ptr [col+y*row] = val; // to assign a value


this is what the compiler would have done anyway.

How to compile and run C files from within Notepad++ using NppExec plugin?

For perl,

To run perl script use this procedure

Requirement: You need to setup classpath variable.

Go to plugins->NppExec->Execute

In command section, type this


Save it and give name to it.(I give Perl).

Press OK. If editor wants to restart, do it first.

Now press F6 and you will find your Perl script output on below side.

Note: Not required seperate config for seperate files.

For java,

Requirement: You need to setup JAVA_HOME and classpath variable.

Go to plugins->NppExec->Execute

In command section, type this

cmd /c cd "$(CURRENT_DIRECTORY)"&&"%JAVA_HOME%\bin\javac""$(FULL_CURRENT_PATH)"

your *.class will generate on location of current folder; despite of programming error.

For Python,

Use this Plugin Python Plugin

Go to plugins->NppExec-> Run file in Python intercative

By using this you can run scripts within Notepad++.

For PHP,

No need for different configuration just download this plugin.

PHP Plugin and done.

For C language,

Requirement: You need to setup classpath variable.
I am using MinGW compiler.

Go to plugins->NppExec->Execute

paste this into there



   C:\MinGW32\bin\gcc.exe -g "$(FILE_NAME)" 


(Remember to give above four lines separate lines.)

Now, give name, save and ok.

Restart Npp.

Go to plugins->NppExec->Advanced options.

Menu Item->Item Name (I have C compiler)

Associated Script-> from combo box select the above name of script.

Click on Add/modify and Ok.

Now assign shortcut key as given in first answer.

Press F6 and select script or just press shortcut(I assigned Ctrl+2).

For C++,

Only change g++ instead of gcc and *.cpp instead on *.c

That's it!!

Visual Studio 2015 installer hangs during install?

In my case the Graphics Tools Windows feature installation was hanging forever. I've installed the Optional Windows Feature manually and restarted the setup of VS 2015.

Biggest differences of Thrift vs Protocol Buffers?

And according to the wiki the Thrift runtime doesn't run on Windows.

Sort list in C# with LINQ

Well, the simplest way using LINQ would be something like this:

list = list.OrderBy(x => x.AVC ? 0 : 1)


list = list.OrderByDescending(x => x.AVC)

I believe that the natural ordering of bool values is false < true, but the first form makes it clearer IMO, because everyone knows that 0 < 1.

Note that this won't sort the original list itself - it will create a new list, and assign the reference back to the list variable. If you want to sort in place, you should use the List<T>.Sort method.

Installing SciPy and NumPy using pip

you need the libblas and liblapack dev packages if you are using Ubuntu.

aptitude install libblas-dev liblapack-dev
pip install scipy

delete_all vs destroy_all?

To avoid the fact that destroy_all instantiates all the records and destroys them one at a time, you can use it directly from the model class.

So instead of :

u = User.find_by_name('JohnBoy')

You can do :

u = User.find_by_name('JohnBoy')
UsageIndex.destroy_all "user_id = #{}"

The result is one query to destroy all the associated records

Convert Pandas DataFrame to JSON format

I think what the OP is looking for is:

with open('temp.json', 'w') as f:
    f.write(df.to_json(orient='records', lines=True))

This should do the trick.

Create stacked barplot where each stack is scaled to sum to 100%

You just need to divide each element by the sum of the values in its column.

Doing this should suffice:

data.perc <- apply(data, 2, function(x){x/sum(x)})

Note that the second parameter tells apply to apply the provided function to columns (using 1 you would apply it to rows). The anonymous function, then, gets passed each data column, one at a time.

Submitting a multidimensional array via POST with php

you could submit all parameters with such naming:


then later you do something like this:

foreach ($_REQUEST['params'] as $item) {
    echo $item['topdiameter'];
    echo $item['bottomdiameter'];

How to stop PHP code execution?

You can use __halt_compiler function which will Halt the compiler execution

C++ cout hex values?

How are you!

#include <iostream>
#include <iomanip>

unsigned char buf0[] = {4, 85, 250, 206};
for (int i = 0;i < sizeof buf0 / sizeof buf0[0]; i++) {
    std::cout << std::setfill('0') 
              << std::setw(2) 
              << std::uppercase 
              << std::hex << (0xFF & buf0[i]) << " ";

CURRENT_TIMESTAMP in milliseconds

I faced the same issue recently and I created a small github project that contains a new mysql function UNIX_TIMESTAMP_MS() that returns the current timestamp in milliseconds.

Also you can do the following :


The project is located here :

To compile you need to Just run make compile in the project root.

Then you need to only copy the shared library in the /usr/lib/mysql/plugin/ (or whatever the plugin folder is on your machine.)

After this just open a mysql console and run :


I hope this will help, Silviu

Upload DOC or PDF using PHP


    //create table


    -- Database: `mydb`

    -- --------------------------------------------------------

    -- Table structure for table `tbl_user_data`

    CREATE TABLE `tbl_user_data` (
      `attachment_id` int(11) NOT NULL,
      `attachment` varchar(200) NOT NULL

    -- Indexes for dumped tables

    -- Indexes for table `tbl_user_data`
    ALTER TABLE `tbl_user_data`
      ADD PRIMARY KEY (`attachment_id`);

    -- AUTO_INCREMENT for dumped tables

    -- AUTO_INCREMENT for table `tbl_user_data`
    ALTER TABLE `tbl_user_data`
      MODIFY `attachment_id` int(11) NOT NULL AUTO_INCREMENT;

    $servername = "localhost";
    $username = "root";
    $password = "";
    // Create connection
    $dbname = "myDB";
    // Create connection
    $conn = new mysqli($servername, $username, $password, $dbname);
    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);


      $statusMsg = '';

      //file upload path
      $targetDir = "resumeUpload/";
      $fileName = basename($_FILES["resume"]["name"]);
      $targetFilePath = $targetDir . $newFileName;
      $fileType = pathinfo($targetFilePath,PATHINFO_EXTENSION);

      if(!empty($_FILES["resume"]["name"])) {
          //allow certain file formats
          //$allowTypes = array('jpg','png','jpeg','gif','pdf','docx','doc');
          $allowTypes = array('pdf','docx','doc');
          if(in_array($fileType, $allowTypes)){
              //upload file to server
              if(move_uploaded_file($_FILES["resume"]["tmp_name"], $targetFilePath)){
                  $statusMsg = "The file ".$fileName. " has been uploaded.";
                  $statusMsg = "Sorry, there was an error uploading your file.";
              $statusMsg = 'Sorry, only DOC,DOCX, & PDF files are allowed to upload.';
          $statusMsg = 'Please select a file to upload.';

      //display status message
      echo $statusMsg;

      $sql="INSERT INTO `tbl_user_data` (`attachment_id`, `attachment`) VALUES
      ('NULL', '$newFileName')";

      if (mysqli_query($conn, $sql)) {

       $last_id = mysqli_insert_id($conn);
         echo "upload success";
      } else {
          echo "Error: " . $sql . "<br>" . mysqli_error($conn);


    <form id="frm_upload" action="" method="post" enctype="multipart/form-data">
    Upload Resume:<input type="file" name="resume" id="resume">
    <button type="submit" name="submit">Apply  Now</button> 

     //output sample[![check here for sample output][1]][1]

Conditional formatting using AND() function

Same issues as others reported - using Excel 2016. Found that when applying conditional formulas against tables; AND, multiplying the conditions, and adding the conditions failed. Had to create the TRUE/FALSE logic myself:


No 'Access-Control-Allow-Origin' header is present on the requested resource - Resteasy

Your resource methods won't get hit, so their headers will never get set. The reason is that there is what's called a preflight request before the actual request, which is an OPTIONS request. So the error comes from the fact that the preflight request doesn't produce the necessary headers.

For RESTeasy, you should use CorsFilter. You can see here for some example how to configure it. This filter will handle the preflight request. So you can remove all those headers you have in your resource methods.

See Also:

How to backup MySQL database in PHP?

While you can execute backup commands from PHP, they don't really have anything to do with PHP. It's all about MySQL.

I'd suggest using the mysqldump utility to back up your database. The documentation can be found here :

The basic usage of mysqldump is

mysqldump -u user_name -p name-of-database >file_to_write_to.sql

You can then restore the backup with a command like

mysql -u user_name -p <file_to_read_from.sql

Do you have access to cron? I'd suggest making a PHP script that runs mysqldump as a cron job. That would be something like



$result=exec('mysqldump database_name --password=your_pass --user=root --single-transaction >/var/backups/'.$filename,$output);

if(empty($output)){/* no output is good */}
else {/* we have something to log the output here*/}

If mysqldump is not available, the article describes another method, using the SELECT INTO OUTFILE and LOAD DATA INFILE commands. The only connection to PHP is that you're using PHP to connect to the database and execute the SQL commands. You could also do this from the command line MySQL program, the MySQL monitor.

It's pretty simple, you're writing an SQL file with one command, and loading/executing it when it's time to restore.

You can find the docs for select into outfile here (just search the page for outfile). LOAD DATA INFILE is essentially the reverse of this. See here for the docs.

Tensorflow: how to save/restore a model?

Tensorflow 2 Docs

Saving Checkpoints

Adapted from the docs

# -------------------------
# -----  Toy Context  -----
# -------------------------
import tensorflow as tf

class Net(tf.keras.Model):
    """A simple linear model."""

    def __init__(self):
        super(Net, self).__init__()
        self.l1 = tf.keras.layers.Dense(5)

    def call(self, x):
        return self.l1(x)

def toy_dataset():
    inputs = tf.range(10.0)[:, None]
    labels = inputs * 5.0 + tf.range(5.0)[None, :]
    return (, y=labels)).repeat().batch(2)

def train_step(net, example, optimizer):
    """Trains `net` on `example` using `optimizer`."""
    with tf.GradientTape() as tape:
        output = net(example["x"])
        loss = tf.reduce_mean(tf.abs(output - example["y"]))
    variables = net.trainable_variables
    gradients = tape.gradient(loss, variables)
    optimizer.apply_gradients(zip(gradients, variables))
    return loss

# ----------------------------
# -----  Create Objects  -----
# ----------------------------

net = Net()
opt = tf.keras.optimizers.Adam(0.1)
dataset = toy_dataset()
iterator = iter(dataset)
ckpt = tf.train.Checkpoint(
    step=tf.Variable(1), optimizer=opt, net=net, iterator=iterator
manager = tf.train.CheckpointManager(ckpt, "./tf_ckpts", max_to_keep=3)

# ----------------------------
# -----  Train and Save  -----
# ----------------------------

if manager.latest_checkpoint:
    print("Restored from {}".format(manager.latest_checkpoint))
    print("Initializing from scratch.")

for _ in range(50):
    example = next(iterator)
    loss = train_step(net, example, opt)
    if int(ckpt.step) % 10 == 0:
        save_path =
        print("Saved checkpoint for step {}: {}".format(int(ckpt.step), save_path))
        print("loss {:1.2f}".format(loss.numpy()))

# ---------------------
# -----  Restore  -----
# ---------------------

# In another script, re-initialize objects
opt = tf.keras.optimizers.Adam(0.1)
net = Net()
dataset = toy_dataset()
iterator = iter(dataset)
ckpt = tf.train.Checkpoint(
    step=tf.Variable(1), optimizer=opt, net=net, iterator=iterator
manager = tf.train.CheckpointManager(ckpt, "./tf_ckpts", max_to_keep=3)

# Re-use the manager code above ^

if manager.latest_checkpoint:
    print("Restored from {}".format(manager.latest_checkpoint))
    print("Initializing from scratch.")

for _ in range(50):
    example = next(iterator)
    # Continue training or evaluate etc.

More links

Checkpoints capture the exact value of all parameters (tf.Variable objects) used by a model. Checkpoints do not contain any description of the computation defined by the model and thus are typically only useful when source code that will use the saved parameter values is available.

The SavedModel format on the other hand includes a serialized description of the computation defined by the model in addition to the parameter values (checkpoint). Models in this format are independent of the source code that created the model. They are thus suitable for deployment via TensorFlow Serving, TensorFlow Lite, TensorFlow.js, or programs in other programming languages (the C, C++, Java, Go, Rust, C# etc. TensorFlow APIs).

(Highlights are my own)

Tensorflow < 2

From the docs:


# Create some variables.
v1 = tf.get_variable("v1", shape=[3], initializer = tf.zeros_initializer)
v2 = tf.get_variable("v2", shape=[5], initializer = tf.zeros_initializer)

inc_v1 = v1.assign(v1+1)
dec_v2 = v2.assign(v2-1)

# Add an op to initialize the variables.
init_op = tf.global_variables_initializer()

# Add ops to save and restore all the variables.
saver = tf.train.Saver()

# Later, launch the model, initialize the variables, do some work, and save the
# variables to disk.
with tf.Session() as sess:
  # Do some work with the model.
  # Save the variables to disk.
  save_path =, "/tmp/model.ckpt")
  print("Model saved in path: %s" % save_path)



# Create some variables.
v1 = tf.get_variable("v1", shape=[3])
v2 = tf.get_variable("v2", shape=[5])

# Add ops to save and restore all the variables.
saver = tf.train.Saver()

# Later, launch the model, use the saver to restore variables from disk, and
# do some work with the model.
with tf.Session() as sess:
  # Restore variables from disk.
  saver.restore(sess, "/tmp/model.ckpt")
  print("Model restored.")
  # Check the values of the variables
  print("v1 : %s" % v1.eval())
  print("v2 : %s" % v2.eval())


Many good answer, for completeness I'll add my 2 cents: simple_save. Also a standalone code example using the API.

Python 3 ; Tensorflow 1.14

import tensorflow as tf
from tensorflow.saved_model import tag_constants

with tf.Graph().as_default():
    with tf.Session() as sess:

        # Saving
        inputs = {
            "batch_size_placeholder": batch_size_placeholder,
            "features_placeholder": features_placeholder,
            "labels_placeholder": labels_placeholder,
        outputs = {"prediction": model_output}
            sess, 'path/to/your/location/', inputs, outputs


graph = tf.Graph()
with restored_graph.as_default():
    with tf.Session() as sess:
        batch_size_placeholder = graph.get_tensor_by_name('batch_size_placeholder:0')
        features_placeholder = graph.get_tensor_by_name('features_placeholder:0')
        labels_placeholder = graph.get_tensor_by_name('labels_placeholder:0')
        prediction = restored_graph.get_tensor_by_name('dense/BiasAdd:0'), feed_dict={
            batch_size_placeholder: some_value,
            features_placeholder: some_other_value,
            labels_placeholder: another_value

Standalone example

Original blog post

The following code generates random data for the sake of the demonstration.

  1. We start by creating the placeholders. They will hold the data at runtime. From them, we create the Dataset and then its Iterator. We get the iterator's generated tensor, called input_tensor which will serve as input to our model.
  2. The model itself is built from input_tensor: a GRU-based bidirectional RNN followed by a dense classifier. Because why not.
  3. The loss is a softmax_cross_entropy_with_logits, optimized with Adam. After 2 epochs (of 2 batches each), we save the "trained" model with tf.saved_model.simple_save. If you run the code as is, then the model will be saved in a folder called simple/ in your current working directory.
  4. In a new graph, we then restore the saved model with tf.saved_model.loader.load. We grab the placeholders and logits with graph.get_tensor_by_name and the Iterator initializing operation with graph.get_operation_by_name.
  5. Lastly we run an inference for both batches in the dataset, and check that the saved and restored model both yield the same values. They do!


import os
import shutil
import numpy as np
import tensorflow as tf
from tensorflow.python.saved_model import tag_constants

def model(graph, input_tensor):
    """Create the model which consists of
    a bidirectional rnn (GRU(10)) followed by a dense classifier

        graph (tf.Graph): Tensors' graph
        input_tensor (tf.Tensor): Tensor fed as input to the model

        tf.Tensor: the model's output layer Tensor
    cell = tf.nn.rnn_cell.GRUCell(10)
    with graph.as_default():
        ((fw_outputs, bw_outputs), (fw_state, bw_state)) = tf.nn.bidirectional_dynamic_rnn(
            sequence_length=[10] * 32,
        outputs = tf.concat((fw_outputs, bw_outputs), 2)
        mean = tf.reduce_mean(outputs, axis=1)
        dense = tf.layers.dense(mean, 5, activation=None)

        return dense

def get_opt_op(graph, logits, labels_tensor):
    """Create optimization operation from model's logits and labels

        graph (tf.Graph): Tensors' graph
        logits (tf.Tensor): The model's output without activation
        labels_tensor (tf.Tensor): Target labels

        tf.Operation: the operation performing a stem of Adam optimizer
    with graph.as_default():
        with tf.variable_scope('loss'):
            loss = tf.reduce_mean(tf.nn.softmax_cross_entropy_with_logits(
                    logits=logits, labels=labels_tensor, name='xent'),
        with tf.variable_scope('optimizer'):
            opt_op = tf.train.AdamOptimizer(1e-2).minimize(loss)
        return opt_op

if __name__ == '__main__':
    # Set random seed for reproducibility
    # and create synthetic data
    features = np.random.randn(64, 10, 30)
    labels = np.eye(5)[np.random.randint(0, 5, (64,))]

    graph1 = tf.Graph()
    with graph1.as_default():
        # Random seed for reproducibility
        # Placeholders
        batch_size_ph = tf.placeholder(tf.int64, name='batch_size_ph')
        features_data_ph = tf.placeholder(tf.float32, [None, None, 30], 'features_data_ph')
        labels_data_ph = tf.placeholder(tf.int32, [None, 5], 'labels_data_ph')
        # Dataset
        dataset =, labels_data_ph))
        dataset = dataset.batch(batch_size_ph)
        iterator =, dataset.output_shapes)
        dataset_init_op = iterator.make_initializer(dataset, name='dataset_init')
        input_tensor, labels_tensor = iterator.get_next()

        # Model
        logits = model(graph1, input_tensor)
        # Optimization
        opt_op = get_opt_op(graph1, logits, labels_tensor)

        with tf.Session(graph=graph1) as sess:
            # Initialize variables
            for epoch in range(3):
                batch = 0
                # Initialize dataset (could feed epochs in Dataset.repeat(epochs))
                        features_data_ph: features,
                        labels_data_ph: labels,
                        batch_size_ph: 32
                values = []
                while True:
                        if epoch < 2:
                            # Training
                            _, value =[opt_op, logits])
                            print('Epoch {}, batch {} | Sample value: {}'.format(epoch, batch, value[0]))
                            batch += 1
                            # Final inference
                            print('Epoch {}, batch {} | Final inference | Sample value: {}'.format(epoch, batch, values[-1][0]))
                            batch += 1
                    except tf.errors.OutOfRangeError:
            # Save model state
            cwd = os.getcwd()
            path = os.path.join(cwd, 'simple')
            shutil.rmtree(path, ignore_errors=True)
            inputs_dict = {
                "batch_size_ph": batch_size_ph,
                "features_data_ph": features_data_ph,
                "labels_data_ph": labels_data_ph
            outputs_dict = {
                "logits": logits
                sess, path, inputs_dict, outputs_dict
    # Restoring
    graph2 = tf.Graph()
    with graph2.as_default():
        with tf.Session(graph=graph2) as sess:
            # Restore saved values
            # Get restored placeholders
            labels_data_ph = graph2.get_tensor_by_name('labels_data_ph:0')
            features_data_ph = graph2.get_tensor_by_name('features_data_ph:0')
            batch_size_ph = graph2.get_tensor_by_name('batch_size_ph:0')
            # Get restored model output
            restored_logits = graph2.get_tensor_by_name('dense/BiasAdd:0')
            # Get dataset initializing operation
            dataset_init_op = graph2.get_operation_by_name('dataset_init')

            # Initialize restored dataset
                    features_data_ph: features,
                    labels_data_ph: labels,
                    batch_size_ph: 32

            # Compute inference for both batches in dataset
            restored_values = []
            for i in range(2):
                print('Restored values: ', restored_values[i][0])

    # Check if original inference and restored inference are equal
    valid = all((v == rv).all() for v, rv in zip(values, restored_values))
    print('\nInferences match: ', valid)

This will print:

$ python3

Epoch 0, batch 0 | Sample value: [-0.13851789 -0.3087595   0.12804556  0.20013677 -0.08229901]
Epoch 0, batch 1 | Sample value: [-0.00555491 -0.04339041 -0.05111827 -0.2480045  -0.00107776]
Epoch 1, batch 0 | Sample value: [-0.19321944 -0.2104792  -0.00602257  0.07465433  0.11674127]
Epoch 1, batch 1 | Sample value: [-0.05275984  0.05981954 -0.15913513 -0.3244143   0.10673307]
Epoch 2, batch 0 | Final inference | Sample value: [-0.26331693 -0.13013336 -0.12553    -0.04276478  0.2933622 ]
Epoch 2, batch 1 | Final inference | Sample value: [-0.07730117  0.11119192 -0.20817074 -0.35660955  0.16990358]

INFO:tensorflow:Assets added to graph.
INFO:tensorflow:No assets to write.
INFO:tensorflow:SavedModel written to: b'/some/path/simple/saved_model.pb'

INFO:tensorflow:Restoring parameters from b'/some/path/simple/variables/variables'
Restored values:  [-0.26331693 -0.13013336 -0.12553    -0.04276478  0.2933622 ]
Restored values:  [-0.07730117  0.11119192 -0.20817074 -0.35660955  0.16990358]

Inferences match:  True

org.json.simple.JSONArray cannot be cast to org.json.simple.JSONObject

JSONObject site = (JSONObject)jsonSites.get(i); // Exception happens here.

The return type of jsonSites.get(i) is JSONArray not JSONObject. Because sites have two '[', two means there are two arrays here.

How do I auto-hide placeholder text upon focus using css or jquery?

Pure CSS Solution (no JS required)

Building on @Hexodus and @Casey Chu's answers, here is an updated and cross-browser solution that leverages CSS opacity and transitions to fade the placeholder text out. It works for any element that can use placeholders, including textarea and input tags.

::-webkit-input-placeholder { opacity: 1; -webkit-transition: opacity .5s; transition: opacity .5s; }  /* Chrome <=56, Safari < 10 */
:-moz-placeholder { opacity: 1; -moz-transition: opacity .5s; transition: opacity .5s; } /* FF 4-18 */
::-moz-placeholder { opacity: 1; -moz-transition: opacity .5s; transition: opacity .5s; } /* FF 19-51 */
:-ms-input-placeholder { opacity: 1; -ms-transition: opacity .5s; transition: opacity .5s; } /* IE 10+ */
::placeholder { opacity: 1; transition: opacity .5s; } /* Modern Browsers */
*:focus::-webkit-input-placeholder { opacity: 0; } /* Chrome <=56, Safari < 10 */
*:focus:-moz-placeholder { opacity: 0; } /* FF 4-18 */
*:focus::-moz-placeholder { opacity: 0; } /* FF 19-50 */
*:focus:-ms-input-placeholder { opacity: 0; } /* IE 10+ */
*:focus::placeholder { opacity: 0; } /* Modern Browsers */
  <div><label for="a">Input:</label></div>
  <input id="a" type="text" placeholder="CSS native fade out this placeholder text on click/focus" size="60">


  <div><label for="b">Textarea:</label></div>
  <textarea id="b" placeholder="CSS native fade out this placeholder text on click/focus" rows="3"></textarea>


  • Edit 1 (2017): Updated to support modern browsers.
  • Edit 2 (2020): Added the runnable Stack Snippet.

How do I get formatted JSON in .NET using C#?


var js = JsonSerializer.Serialize(obj, new JsonSerializerOptions {
             WriteIndented = true

Laravel 5.4 ‘cross-env’ Is Not Recognized as an Internal or External Command

You are getting the error because you might not have run the command npm install first.

i.e. First, run npm install and then npm run dev

Best way to test for a variable's existence in PHP; isset() is clearly broken

Try using


It seems the only time a variable is not set is when it is specifically unset($v). It sounds like your meaning of 'existence' is different than PHP's definition. NULL is certainly existing, it is NULL.

Tracing XML request/responses with JAX-WS

with logback.xml configuration files, you can do :

<logger name="" level="trace" additivity="false">
    <appender-ref ref="STDOUT"/>

That will log the request and the response like this (depending on your configuration for the log output) :

09:50:23.266 [qtp1068445309-21] DEBUG c.s.x.i.w.t.h.c.HttpTransportPipe - ---[HTTP request - http://xyz:8081/xyz.svc]---
Accept: application/soap+xml, multipart/related
Content-Type: application/soap+xml; charset=utf-8;action="http://xyz.Web.Services/IServiceBase/GetAccessTicket"
User-Agent: JAX-WS RI 2.2.9-b130926.1035 svn-revision#5f6196f2b90e9460065a4c2f4e30e065b245e51e
<?xml version="1.0" ?><S:Envelope xmlns:S="">[CONTENT REMOVED]</S:Envelope>--------------------

09:50:23.312 [qtp1068445309-21] DEBUG c.s.x.i.w.t.h.c.HttpTransportPipe - ---[HTTP response - http://xyz:8081/xyz.svc - 200]---
null: HTTP/1.1 200 OK
Content-Length: 792
Content-Type: application/soap+xml; charset=utf-8
Date: Tue, 12 Feb 2019 14:50:23 GMT
Server: Microsoft-IIS/10.0
X-Powered-By: ASP.NET
<s:Envelope xmlns:s="" xmlns:a="">[CONTENT REMOVED]</s:Envelope>--------------------

Most efficient way to remove special characters from string

HashSet is O(1)
Not sure if it is faster than the existing comparison

private static HashSet<char> ValidChars = new HashSet<char>() { 'a', 'b', 'c', 'A', 'B', 'C', '1', '2', '3', '_' };
public static string RemoveSpecialCharacters(string str)
    StringBuilder sb = new StringBuilder(str.Length / 2);
    foreach (char c in str)
        if (ValidChars.Contains(c)) sb.Append(c);
    return sb.ToString();

I tested and this in not faster than the accepted answer.
I will leave it up as if you needed a configurable set of characters this would be a good solution.

SQL Server find and replace specific word in all rows of specific column

SET number = REPLACE(number, 'KIT', 'CH')
WHERE number like 'KIT%'

or simply this if you are sure that you have no values like this CKIT002

SET number = REPLACE(number, 'KIT', 'CH')

How do you programmatically set an attribute?

Usually, we define classes for this.

class XClass( object ):
   def __init__( self ):
       self.myAttr= None

x= XClass()
x.myAttr= 'magic'

However, you can, to an extent, do this with the setattr and getattr built-in functions. However, they don't work on instances of object directly.

>>> a= object()
>>> setattr( a, 'hi', 'mom' )
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'object' object has no attribute 'hi'

They do, however, work on all kinds of simple classes.

class YClass( object ):

y= YClass()
setattr( y, 'myAttr', 'magic' )

"Fatal error: Cannot redeclare <function>"

If your having a Wordpress theme problem it could be because although you have renamed the theme in your wp_options table you havn't renamed the stylesheet. I struggled with this.

javascript toISOString() ignores timezone offset

moment.js is great but sometimes you don't want to pull a large number of dependencies for simple things.

The following works as well:

var tzoffset = (new Date()).getTimezoneOffset() * 60000; //offset in milliseconds
var localISOTime = (new Date( - tzoffset)).toISOString().slice(0, -1);
// => '2015-01-26T06:40:36.181'

The slice(0, -1) gets rid of the trailing Z which represents Zulu timezone and can be replaced by your own.

How to have multiple colors in a Windows batch file?

Without external tools.This is a self-compiled bat/.net hybrid (should be saved as .BAT) that can be used on any system that have installed .net framework (it's a rare thing to see an windows without .NET framework even for the oldest XP/2003 installations) . It uses compiler to create an exe capable to print strings with different background/foreground color only for the current line.

@if (@X)==(@Y) @end /* JScript comment
@echo off

for /f "tokens=* delims=" %%v in ('dir /b /s /a:-d  /o:-n "%SystemRoot%\Microsoft.NET\Framework\*jsc.exe"') do (
   set "jsc=%%v"

if not exist "%~n0.exe" (
    "%jsc%" /nologo /out:"%~n0.exe" "%~dpsfnx0"

%~n0.exe %*

endlocal & exit /b %errorlevel%


import System;

var arguments:String[] = Environment.GetCommandLineArgs();

var newLine = false;
var output = "";
var foregroundColor = Console.ForegroundColor;
var backgroundColor = Console.BackgroundColor;
var evaluate = false;
var currentBackground=Console.BackgroundColor;
var currentForeground=Console.ForegroundColor;

var jsEscapes = {
  'n': '\n',
  'r': '\r',
  't': '\t',
  'f': '\f',
  'v': '\v',
  'b': '\b'

function decodeJsEscape(_, hex0, hex1, octal, other) {
  var hex = hex0 || hex1;
  if (hex) { return String.fromCharCode(parseInt(hex, 16)); }
  if (octal) { return String.fromCharCode(parseInt(octal, 8)); }
  return jsEscapes[other] || other;

function decodeJsString(s) {
  return s.replace(
      // Matches an escape sequence with UTF-16 in group 1, single byte hex in group 2,
      // octal in group 3, and arbitrary other single-character escapes in group 4.

function printHelp( ) {
   print( arguments[0] + "  -s string [-f foreground] [-b background] [-n] [-e]" );
   print( " " );
   print( " string          String to be printed" );
   print( " foreground      Foreground color - a " );
   print( "                 number between 0 and 15." );
   print( " background      Background color - a " );
   print( "                 number between 0 and 15." );
   print( " -n              Indicates if a new line should" );
   print( "                 be written at the end of the ");
   print( "                 string(by default - no)." );
   print( " -e              Evaluates special character " );
   print( "                 sequences like \\n\\b\\r and etc ");
   print( "" );
   print( "Colors :" );
   for ( var c = 0 ; c < 16 ; c++ ) {

        Console.BackgroundColor = c;
        Console.Write( " " );
        Console.Write( "-"+c );
        Console.WriteLine( "" );


function errorChecker( e:Error ) {
        if ( e.message == "Input string was not in a correct format." ) {
            print( "the color parameters should be numbers between 0 and 15" );
            Environment.Exit( 1 );
        } else if (e.message == "Index was outside the bounds of the array.") {
            print( "invalid arguments" );
            Environment.Exit( 2 );
        } else {
            print ( "Error Message: " + e.message );
            print ( "Error Code: " + ( e.number & 0xFFFF ) );
            print ( "Error Name: " + );
            Environment.Exit( 666 );

function numberChecker( i:Int32 ){
    if( i > 15 || i < 0 ) {
        print("the color parameters should be numbers between 0 and 15");

if ( arguments.length == 1 || arguments[1].toLowerCase() == "-help" || arguments[1].toLowerCase() == "-help"   ) {

for (var arg = 1; arg <= arguments.length-1; arg++ ) {
    if ( arguments[arg].toLowerCase() == "-n" ) {

    if ( arguments[arg].toLowerCase() == "-e" ) {

    if ( arguments[arg].toLowerCase() == "-s" ) {

    if ( arguments[arg].toLowerCase() == "-b" ) {

        try {
            backgroundColor=Int32.Parse( arguments[arg+1] );
        } catch(e) {

    if ( arguments[arg].toLowerCase() == "-f" ) {
        try {
        } catch(e) {

Console.BackgroundColor = backgroundColor ;
Console.ForegroundColor = foregroundColor ;

if ( evaluate ) {

if ( newLine ) {
} else {


Console.BackgroundColor = currentBackground;
Console.ForegroundColor = currentForeground;

Example coloroutput.bat -s "aa\nbb\n\u0025cc" -b 10 -f 3 -n -e

You can also check carlos' color function ->

vector vs. list in STL

Most answers here miss one important detail: what for?

What do you want to keep in the containter?

If it is a collection of ints, then std::list will lose in every scenario, regardless if you can reallocate, you only remove from the front, etc. Lists are slower to traverse, every insertion costs you an interaction with the allocator. It would be extremely hard to prepare an example, where list<int> beats vector<int>. And even then, deque<int> may be better or close, not justyfing the use of lists, which will have greater memory overhead.

However, if you are dealing with large, ugly blobs of data - and few of them - you don't want to overallocate when inserting, and copying due to reallocation would be a disaster - then you may, maybe, be better off with a list<UglyBlob> than vector<UglyBlob>.

Still, if you switch to vector<UglyBlob*> or even vector<shared_ptr<UglyBlob> >, again - list will lag behind.

So, access pattern, target element count etc. still affects the comparison, but in my view - the elements size - cost of copying etc.

CronJob not running

It might also be a timezone problem.

Cron uses the local time.

Run the command timedatectl to see the machine time and make sure that your crontab is in this same timezone.

How to fix HTTP 404 on Github Pages?

In my case the browser had a previous cached version of my app. To avoid getting the cached version, access you url using a random query string:


Root user/sudo equivalent in Cygwin?

I answered this question on SuperUser but only after the OP disregarded the unhelpful answer that was at the time the only answer to the question.

Here is the proper way to elevate permissions in Cygwin, copied from my own answer on SuperUser:

I found the answer on the Cygwin mailing list. To run command with elevated privileges in Cygwin, precede the command with cygstart --action=runas like this:

$ cygstart --action=runas command

This will open a Windows dialogue box asking for the Admin password and run the command if the proper password is entered.

This is easily scripted, so long as ~/bin is in your path. Create a file ~/bin/sudo with the following content:

cygstart --action=runas "$@"

Now make the file executable:

$ chmod +x ~/bin/sudo

Now you can run commands with real elevated privileges:

$ sudo elevatedCommand

You may need to add ~/bin to your path. You can run the following command on the Cygwin CLI, or add it to ~/.bashrc:


Tested on 64-bit Windows 8.

You could also instead of above steps add an alias for this command to ~/.bashrc:

# alias to simulate sudo
alias sudo='cygstart --action=runas'

How can I show and hide elements based on selected option with jQuery?

You're running the code before the DOM is loaded.

Try this:

Live example:

$(function() {    // Makes sure the code contained doesn't run until
                  //     all the DOM elements have loaded

        $('#' + $(this).val()).show();


Why do we use web.xml?

The web.xml file is the deployment descriptor for a Servlet-based Java web application (which most Java web apps are). Among other things, it declares which Servlets exist and which URLs they handle.

The part you cite defines a Servlet Filter. Servlet filters can do all kinds of preprocessing on requests. Your specific example is a filter had the Wicket framework uses as its entry point for all requests because filters are in some way more powerful than Servlets.

Redirect from web api post action

You can check this

public IHttpActionResult GetReport()

   string url = "https://localhost:44305/Templates/ReportPage.html";

   System.Uri uri = new System.Uri(url);

   return Redirect(uri);

Java error: Only a type can be imported. XYZ resolves to a package

I had a similar issue. In eclipse I compared my project with a sample project which is working fine (generated by a maven archetype). I found my project has missed 2 lines in /.classpath file. I copied those 2 lines and it fixed the issue. It seems even though I set build path in project preferences, eclipse has not updated accordingly for some reasons.

<?xml version="1.0" encoding="UTF-8"?>
    <classpathentry kind="src" output="target/classes" path="src/main/java"/>
    <classpathentry kind="src" output="target/test-classes" path="src/test/java"/>

How to truncate milliseconds off of a .NET DateTime

Regarding Diadistis response. This worked for me, except I had to use Floor to remove the fractional part of the division before the multiplication. So,

d = new DateTime((d.Ticks / TimeSpan.TicksPerSecond) * TimeSpan.TicksPerSecond);


d = new DateTime(Math.Floor(d.Ticks / TimeSpan.TicksPerSecond) * TimeSpan.TicksPerSecond);

I would have expected the division of two Long values to result in a Long, thus removing the decimal part, but it resolves it as a Double leaving the exact same value after the multiplication.


Java String remove all non numeric characters

A way to replace it with a java 8 stream:

public static void main(String[] args) throws IOException
    String test = "ab19198zxncvl1308j10923.";
    StringBuilder result = new StringBuilder();

    test.chars().mapToObj( i-> (char)i ).filter( c -> Character.isDigit(c) || c == '.' ).forEach( c -> result.append(c) );

    System.out.println( result ); //returns 19198.130810923.

fastest way to export blobs from table into individual files

I came here looking for exporting blob into file with least effort. CLR functions is not something what I'd call least effort. Here described lazier one, using OLE Automation:

declare @init int
declare @file varbinary(max) = CONVERT(varbinary(max), N'your blob here')
declare @filepath nvarchar(4000) = N'c:\temp\you file name here.txt'

EXEC sp_OACreate 'ADODB.Stream', @init OUTPUT; -- An instace created
EXEC sp_OASetProperty @init, 'Type', 1; 
EXEC sp_OAMethod @init, 'Open'; -- Calling a method
EXEC sp_OAMethod @init, 'Write', NULL, @file; -- Calling a method
EXEC sp_OAMethod @init, 'SaveToFile', NULL, @filepath, 2; -- Calling a method
EXEC sp_OAMethod @init, 'Close'; -- Calling a method
EXEC sp_OADestroy @init; -- Closed the resources

You'll potentially need to allow to run OA stored procedures on server (and then turn it off, when you're done):

sp_configure 'show advanced options', 1;  
sp_configure 'Ole Automation Procedures', 1;