Programs & Examples On #Hypervisor

How to disable Hyper-V in command line?

Command line:

dism /online /disable-feature /featurename:microsoft-hyper-v-all

If anyone is getting:

We couldn’t complete the updates, Undoing changes

after trying to disable the Hyper-V, try uninstalling Hyper-V virtual network adapters from your Device Manager->Network Adapters

How to schedule a task to run when shutting down windows

You can run a batch file that calls your program, check out the discussion here for how to do it:

(from google search: windows schedule task run at shut down)

Remove a child with a specific attribute, in SimpleXML for PHP

Just unset the node:

$str = <<<STR

$xml = simplexml_load_string($str);
unset($xml –> a –> b –> c); // this would remove node c
echo $xml –> asXML(); // xml document string without node c

This code was taken from How to delete / remove nodes in SimpleXML.

initializing strings as null vs. empty string

Empty-ness and "NULL-ness" are two different concepts. As others mentioned the former can be achieved via std::string::empty(), the latter can be achieved with boost::optional<std::string>, e.g.:

boost::optional<string> myStr;
if (myStr) { // myStr != NULL
    // ...

Finding an item in a List<> using C#

item = objects.Find(obj =>;

UITableView, Separator color where to set?

Try + (instancetype)appearance of UITableView:


[[UITableView appearance] setSeparatorColor:[UIColor blackColor]]; // set your desired colour in place of "[UIColor blackColor]"

Swift 3.0:

UITableView.appearance().separatorColor = // set your desired colour in place of ""

Note: Change will reflect to all tables used in application.

How to test an Oracle Stored Procedure with RefCursor return type?

Something like this lets you test your procedure on almost any client:

  v_a   VARCHAR2(10);
  v_b   VARCHAR2(10);

    FETCH v_cur INTO v_a, v_b;
    dbms_output.put_line(v_a || ' ' || v_b);
  CLOSE v_cur;

Basically, your test harness needs to support the definition of a SYS_REFCURSOR variable and the ability to call your procedure while passing in the variable you defined, then loop through the cursor result set. PL/SQL does all that, and anonymous blocks are easy to set up and maintain, fairly adaptable, and quite readable to anyone who works with PL/SQL.

Another, albeit similar way would be to build a named procedure that does the same thing, and assuming the client has a debugger (like SQL Developer, PL/SQL Developer, TOAD, etc.) you could then step through the execution.

jQuery: get the file name selected from <input type="file" />

The simplest way is to simply use the following line of jquery, using this you don't get the /fakepath nonsense, you straight up get the file that was uploaded:

$('input[type=file]')[0].files[0]; // This gets the file
$('#idOfFileUpload')[0].files[0]; // This gets the file with the specified id

Some other useful commands are:

To get the name of the file:

$('input[type=file]')[0].files[0].name; // This gets the file name

To get the type of the file:

If I were to upload a PNG, it would return image/png


To get the size (in bytes) of the file:


Also you don't have to use these commands on('change', you can get the values at any time, for instance you may have a file upload and when the user clicks upload, you simply use the commands I listed.

how to find host name from IP with out login to the host

If you are specifically looking for a Windows machine, try below command:

nbtstat -a

How to Convert a Text File into a List in Python


crimefile = open(fileName, 'r')
yourResult = [line.split(',') for line in crimefile.readlines()]

How do I get video durations with YouTube API version 3?

Duration in seconds using Python 2.7 and the YouTube API v3:

        dur = entry['contentDetails']['duration']
            minutes = int(dur[2:4]) * 60
            minutes = 0
            hours = int(dur[:2]) * 60 * 60
            hours = 0

        secs = int(dur[5:7])
        print hours, minutes, secs
        video.duration = hours + minutes + secs
        print video.duration
    except Exception as e:
        print "Couldnt extract time: %s" % e

Loop over array dimension in plpgsql

Since PostgreSQL 9.1 there is the convenient FOREACH:

   m   varchar[];
   arr varchar[] := array[['key1','val1'],['key2','val2']];
      RAISE NOTICE 'another_func(%,%)',m[1], m[2];

Solution for older versions:

   arr varchar[] := '{{key1,val1},{key2,val2}}';
   FOR i IN array_lower(arr, 1) .. array_upper(arr, 1)
      RAISE NOTICE 'another_func(%,%)',arr[i][1], arr[i][2];

Also, there is no difference between varchar[] and varchar[][] for the PostgreSQL type system. I explain in more detail here.

The DO statement requires at least PostgreSQL 9.0, and LANGUAGE plpgsql is the default (so you can omit the declaration).

How can I write text on a HTML5 canvas element?

Canvas text support is actually pretty good - you can control font, size, color, horizontal alignment, vertical alignment, and you can also get text metrics to get the text width in pixels. In addition, you can also use canvas transforms to rotate, stretch and even invert text.

The response content cannot be parsed because the Internet Explorer engine is not available, or

In your invoke web request just use the parameter -UseBasicParsing

e.g. in your script (line 2) you should use:

$rss = Invoke-WebRequest -Uri $url -UseBasicParsing

According to the documentation, this parameter is necessary on systems where IE isn't installed or configured:

Uses the response object for HTML content without Document Object Model (DOM) parsing. This parameter is required when Internet Explorer is not installed on the computers, such as on a Server Core installation of a Windows Server operating system.

How do you fix a bad merge, and replay your good commits onto a fixed merge?

Rewriting Git history demands changing all the affected commit ids, and so everyone who's working on the project will need to delete their old copies of the repo, and do a fresh clone after you've cleaned the history. The more people it inconveniences, the more you need a good reason to do it - your superfluous file isn't really causing a problem, but if only you are working on the project, you might as well clean up the Git history if you want to!

To make it as easy as possible, I'd recommend using the BFG Repo-Cleaner, a simpler, faster alternative to git-filter-branch specifically designed for removing files from Git history. One way in which it makes your life easier here is that it actually handles all refs by default (all tags, branches, etc) but it's also 10 - 50x faster.

You should carefully follow the steps here: - but the core bit is just this: download the BFG jar (requires Java 6 or above) and run this command:

$ java -jar bfg.jar --delete-files filename.orig my-repo.git

Your entire repository history will be scanned, and any file named filename.orig (that's not in your latest commit) will be removed. This is considerably easier than using git-filter-branch to do the same thing!

Full disclosure: I'm the author of the BFG Repo-Cleaner.

Can I run HTML files directly from GitHub, instead of just viewing their source?

I had the same problem for my project Ratio.js and here's what I did.

Problem: prevents files from rendering/executing when the source is viewed by setting the content type/MIME to plain text.

Solution: Have a web page import the files.


Use or to create a webpage online then save it. Navigate to your file in and click the 'raw' button to get the direct link to the file. From there, import the file using the appropriate tag and attribute.

        <link rel="stylesheet" href="" type="text/css" media="screen" />
        <h1 id="qunit-header">QUnit example</h1>
        <h2 id="qunit-banner"></h2>
        <div id="qunit-testrunner-toolbar"></div>
        <h2 id="qunit-userAgent"></h2>
        <ol id="qunit-tests"></ol>
        <div id="qunit-fixture">test markup, will be hidden</div>
        <script src=""></script>
        <script type="text/javascript" src=""></script>  
        <script type="text/javascript" src=""></script>  
        <script type="text/javascript" src=""></script>  

Live Demo:

Note: Note for you can get direct access to the result page by adding show to the end of the url. Like so: could create a project page and render your HTML files from there. You can create a project page at

Once created you can then access the link through http://*accountName**projectName*/ Example:

Why does only the first line of this Windows batch file execute but all three lines execute in a command shell?

To execute more Maven builds from one script you shall use the Windows call function in the following way:

call mvn install:install-file -DgroupId=gdata -DartifactId=base -Dversion=1.0 -Dfile=gdata-base-1.0.jar  -Dpackaging=jar -DgeneratePom=true
call mvn install:install-file -DgroupId=gdata -DartifactId=blogger -Dversion=2.0 -Dfile=gdata-blogger-2.0.jar  -Dpackaging=jar -DgeneratePom=true
call mvn install:install-file -DgroupId=gdata -DartifactId=blogger-meta -Dversion=2.0 -Dfile=gdata-blogger-meta-2.0.jar  -Dpackaging=jar -DgeneratePom=true

How to write an async method with out parameter?

I had the same problem as I like using the Try-method-pattern which basically seems to be incompatible to the async-await-paradigm...

Important to me is that I can call the Try-method within a single if-clause and do not have to pre-define the out-variables before, but can do it in-line like in the following example:

if (TryReceive(out string msg))
    // use msg

So I came up with the following solution:

  1. Define a helper struct:

     public struct AsyncOut<T, OUT>
         private readonly T returnValue;
         private readonly OUT result;
         public AsyncOut(T returnValue, OUT result)
             this.returnValue = returnValue;
             this.result = result;
         public T Out(out OUT result)
             result = this.result;
             return returnValue;
         public T ReturnValue => returnValue;
         public static implicit operator AsyncOut<T, OUT>((T returnValue ,OUT result) tuple) => 
             new AsyncOut<T, OUT>(tuple.returnValue, tuple.result);
  2. Define async Try-method like this:

     public async Task<AsyncOut<bool, string>> TryReceiveAsync()
         string message;
         bool success;
         // ...
         return (success, message);
  3. Call the async Try-method like this:

     if ((await TryReceiveAsync()).Out(out string msg))
         // use msg

For multiple out parameters you can define additional structs (e.g. AsyncOut<T,OUT1, OUT2>) or you can return a tuple.

Error in strings.xml file in Android

post your complete string. Though, my guess is there is an apostrophe (') character in your string. replace it with (\') and it will fix the issue. for example,

<string name="terms">
Hey Mr. Android, are you stuck?  Here, I\'ll clear a path for you.  


Simple way to read single record from MySQL

One more answer for object oriented style. Found this solution for me:

$id = $dbh->query("SELECT id FROM mytable WHERE mycolumn = 'foo'")->fetch_object()->id;

gives back just one id. Verify that your design ensures you got the right one.

Android: Go back to previous activity

public void onBackPressed() {

and if you want on button click go back then simply put

bbsubmit.setOnClickListener(new View.OnClickListener() {
    public void onClick(View v) {

python: how to send mail with TO, CC and BCC?

Email headers don't matter to the smtp server. Just add the CC and BCC recipients to the toaddrs when you send your email. For CC, add them to the CC header.

toaddr = '[email protected]'
cc = ['[email protected]','[email protected]']
bcc = ['[email protected]']
fromaddr = '[email protected]'
message_subject = "disturbance in sector 7"
message_text = "Three are dead in an attack in the sewers below sector 7."
message = "From: %s\r\n" % fromaddr
        + "To: %s\r\n" % toaddr
        + "CC: %s\r\n" % ",".join(cc)
        + "Subject: %s\r\n" % message_subject
        + "\r\n" 
        + message_text
toaddrs = [toaddr] + cc + bcc
server = smtplib.SMTP('')
server.sendmail(fromaddr, toaddrs, message)

What static analysis tools are available for C#?

Code violation detection Tools:

  • Fxcop, excellent tool by Microsoft. Check compliance with .net framework guidelines.

    Edit October 2010: No longer available as a standalone download. It is now included in the Windows SDK and after installation can be found in Program Files\Microsoft SDKs\Windows\ [v7.1] \Bin\FXCop\FxCopSetup.exe

    Edit February 2018: This functionality has now been integrated into Visual Studio 2012 and later as Code Analysis

  • Clocksharp, based on code source analysis (to C# 2.0)

  • Mono.Gendarme, similar to Fxcop but with an opensource licence (based on Mono.Cecil)

  • Smokey, similar to Fxcop and Gendarme, based on Mono.Cecil. No longer on development, the main developer works with Gendarme team now.

  • Coverity Prevent™ for C#, commercial product

  • PRQA QA·C#, commercial product

  • PVS-Studio, commercial product

  • CAT.NET, visual studio addin that helps identification of security flaws Edit November 2019: Link is dead.

  • CodeIt.Right

  • Spec#

  • Pex

  • SonarQube, FOSS & Commercial options to support writing cleaner and safer code.

Quality Metric Tools:

  • NDepend, great visual tool. Useful for code metrics, rules, diff, coupling and dependency studies.
  • Nitriq, free, can easily write your own metrics/constraints, nice visualizations. Edit February 2018: download links now dead. Edit June 17, 2019: Links not dead.
  • RSM Squared, based on code source analysis
  • C# Metrics, using a full parse of C#
  • SourceMonitor, an old tool that occasionally gets updates
  • Code Metrics, a Reflector add-in
  • Vil, old tool that doesn't support .NET 2.0. Edit January 2018: Link now dead

Checking Style Tools:

  • StyleCop, Microsoft tool ( run from inside of Visual Studio or integrated into an MSBuild project). Also available as an extension for Visual Studio 2015 and C#6.0
  • Agent Smith, code style validation plugin for ReSharper

Duplication Detection:

  • Simian, based on source code. Works with plenty languages.
  • CloneDR, detects parameterized clones only on language boundaries (also handles many languages other than C#)
  • Clone Detective a Visual Studio plugin. (It uses ConQAT internally)
  • Atomiq, based on source code, plenty of languages, cool "wheel" visualization

General Refactoring tools

  • ReSharper - Majorly cool C# code analysis and refactoring features

How can I remove an entry in global configuration with git config?

You can check all the config settings using

git config --global --list

You can remove the setting for example username

git config --global --unset

You can edit the configuration or remove the config setting manually by hand using:

git config --global --edit 

Check if property has attribute

You can use a common (generic) method to read attribute over a given MemberInfo

public static bool TryGetAttribute<T>(MemberInfo memberInfo, out T customAttribute) where T: Attribute {
                var attributes = memberInfo.GetCustomAttributes(typeof(T), false).FirstOrDefault();
                if (attributes == null) {
                    customAttribute = null;
                    return false;
                customAttribute = (T)attributes;
                return true;

Is there any ASCII character for <br>?

The answer is amp#13; — change "amp" to the ampersand sign and go.

sklearn: Found arrays with inconsistent numbers of samples when calling

expects X(feature matrix)

Try to put your features in a tuple like this:

features = ['TV', 'Radio', 'Newspaper']
X = data[features]

Offset a background image from the right using CSS

The most appropriate answer is the new four-value syntax for background-position, but until all browsers support it your best approach is a combination of earlier responses in the following order:

background: url(image.png) no-repeat 97% center; /* default, Android, Sf < 6 */
background-position: -webkit-calc(100% - 10px) center; /* Sf 6 */
background-position: right 10px center; /* Cr 25+, FF 13+, IE 9+, Op 10.5+ */

How can I ssh directly to a particular directory?

You could add

cd /some/directory/somewhere/named/Foo

to your .bashrc file (or .profile or whatever you call it) at the other host. That way, no matter what you do or where you ssh from, whenever you log onto that server, it will cd to the proper directory for you, and all you have to do is use ssh like normal.

Of curse, rogeriopvl's solution works too, but it's a tad bit more verbose, and you have to remember to do it every time (unless you make an alias) so it seems a bit less "fun".

How to dismiss a Twitter Bootstrap popover by clicking outside?

This approach ensures that you can close a popover by clicking anywhere on the page. If you click on another clickable entity, it hides all other popovers. The animation:false is required else you will get a jquery .remove error in your console.

 trigger: 'manual',
 animation: false
 }).click (evt) ->

$('html').on 'click', (evt) ->

Send JSON data from Javascript to PHP?

There are 3 relevant ways to send Data from client Side (HTML, Javascript, Vbscript ..etc) to Server Side (PHP, ASP, JSP ...etc)

1. HTML form Posting Request (GET or POST).
2. AJAX (This also comes under GET and POST)
3. Cookie

HTML form Posting Request (GET or POST)

This is most commonly used method, and we can send more Data through this method


This is Asynchronous method and this has to work with secure way, here also we can send more Data.


This is nice way to use small amount of insensitive data. this is the best way to work with bit of data.

In your case You can prefer HTML form post or AJAX. But before sending to server validate your json by yourself or use link like

If you have Json Object convert it into String using JSON.stringify(object), If you have JSON string send it as it is.

Add click event on div tag using javascript

Just add the onclick-attribute:

<div class="drill_cursor" onclick='alert("youClickedMe!");'>

It's javascript, but it's automatically bound using an html-attribute instead of manually binding it within <script> tags - maybe it does what you want.

While it might be good enough for very small projects or test pages, you should definitly consider using addEventListener (as pointed out by other answers), if you expect the code to grow and stay maintainable.

Case-insensitive search in Rails model

An alternative can be

c = Product.find_by("LOWER(name)= ?", name.downcase)

Missing Maven dependencies in Eclipse project

For me the problem was maven couldn't find the settings.xml file which is located in myMavenFolder\conf.

What I did to fix the issue was to select the right location of the settings.xml file from eclipse:
Window -> Preferences -> Maven -> User Settings

Finally, hit apply and update your project

Execute combine multiple Linux commands in one line

If you want to execute all the commands, whether the previous one executes or not, you can use semicolon (;) to separate the commands.

cd /my_folder; rm *.jar; svn co path to repo; mvn compile package install

If you want to execute the next command only if the previous command succeeds, then you can use && to separate the commands.

cd /my_folder && rm *.jar && svn co path to repo && mvn compile package install

In your case, the execution of consecutive commands seems to depend upon the previous commands, so use the second example i.e. use && to join the commands.

.htaccess redirect http to https

This makes sure that redirects work for all combinations of intransparent proxies.

This includes the case client <http> proxy <https> webserver.

# behind proxy
RewriteCond %{HTTP:X-FORWARDED-PROTO} ^http$
RewriteRule (.*) https://%{HTTP_HOST}/$1 [R=301,L]

# plain
RewriteCond %{REQUEST_SCHEME} ^http$ [NC,OR]
RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}/$1 [R=301,L]

Converting to UTC timestamp in Python

A complete time-string contains:

  • date
  • time
  • utcoffset [+HHMM or -HHMM]

For example:

1970-01-01 06:00:00 +0500 == 1970-01-01 01:00:00 +0000 == UNIX timestamp:3600

$ python3
>>> from datetime import datetime
>>> from calendar import timegm
>>> tm = '1970-01-01 06:00:00 +0500'
>>> fmt = '%Y-%m-%d %H:%M:%S %z'
>>> timegm(datetime.strptime(tm, fmt).utctimetuple())


UNIX timestamp is a floating point number expressed in seconds since the epoch, in UTC.


$ python3
>>> from datetime import datetime, timezone, timedelta
>>> from calendar import timegm
>>> dt = datetime(1970, 1, 1, 6, 0)
>>> tz = timezone(timedelta(hours=5))
>>> timegm(dt.replace(tzinfo=tz).utctimetuple())

cat, grep and cut - translated to python

In Python, without external dependencies, it is something like this (untested):

with open("filename") as origin:
    for line in origin:
        if not "something" in line:
            print line.split('"')[1]
        except IndexError:

Remove URL parameters without refreshing page

if I have a special tag at the end of my URL like: Here is the below code to remove that tag whenever it presents in the URL:

// Remove URL Tag Parameter from Address Bar
if (window.parent.location.href.match(/tag=/)){
    if (typeof (history.pushState) != "undefined") {
        var obj = { Title: document.title, Url: window.parent.location.pathname };
        history.pushState(obj, obj.Title, obj.Url);
    } else {
        window.parent.location = window.parent.location.pathname;

This gives the idea to remove one or more (or all) parameters from URL

With window.location.pathname you basically get everything before '?' in the url.

var pathname = window.location.pathname; // Returns path only

var url = window.location.href; // Returns full URL

Copy values from one column to another in the same table

UPDATE `table_name` SET `test` = `number`

You can also do any mathematical changes in the process or use MySQL functions to modify the values.

How do I completely uninstall Node.js, and reinstall from beginning (Mac OS X)

Docker - alternative approach

Docker is some-kind of super-fast virtual machine which can be use to run tools like node (instead install them directly on mac-os). Advantages to do it are following

  • all stuff ('milions' node files) are install inside docker image/container (they encapsulated in few inner-docker files)

  • you can map your mac directory with project to your docker container and have access to node - but outside docker, mac-os sytem don't even know that node is installed. So you get some kind of 'virtual' console with available node commands which can works on real files

  • you can easily kill node by find it by docker ps and kill by docker rm -f name_or_num

  • you can easily uninstall docker image/containers by one command docker rmi ... and get free space - and install it again by run script (below)

  • your node is encapsulated inside docker and don't have access to whole system - only to folders you map to it

  • you can run node services and easily map they port to mac port and have access to it from web browser

  • you can run many node versions at the same time

  • in similar way you can install other tools like (in many versions in same time): php, databases, redis etc. - inside docker without any interaction with mac-os (which not notice such software at all). E.g. you can run at the same time 3 mysql db with different versions and 3 php application with different php version ... - so you can have many tools but clean system

  • TEAM WORK: such enviroment can be easily cloned into other machines (and even to windows/linux systems - with some modifications) and provide identical docker-level environment - so you can easily set up and reuse you scripts/dockerfiles, and setup environment for new team member in very fast way (he just need to install docker and create similar folder-structure and get copy of scripts - thats all). I work this way for 2 year and with my team - and we are very happy


  • Install docker using e.g. this instructions

  • Prepare 'special' directory for work e.g. my directory is /Users/kamil/work (I will use this directory further - but it can be arbitrary) - this directory will be 'interface' between docker containers and your mac file ststem. Inside this dir create following dir structure:

    /Users/kamil/work/code - here you put your projects with code


    /Users/kamil/work/tools/docker-data - here we map containers output data like logs (or database files if someone ouse db etc.)


    /Users/kamil/work/tools/docker/node-cmd - here we put docker node scripts

  • inside tools create file .env which will contain in one place global-paths used in other scripts


  • innside dir ../node-cmd create file dockerfile with following content

    # default  /var/www/html (mapped to .../code folder with projects)
    FROM node
    WORKDIR /work
    # Additional arbitrary tools (ng, gulp, bower)
    RUN npm install -g n @angular/cli bower gulp grunt
    CMD while true; do sleep 10000; done
    # below ports are arbitrary
    EXPOSE 3002 3003 3004 4200

  • innside dir ../node-cmd create file run-container with following content (this file should be executable e.g. by chmod +x run-container) - (notice how we map port-s and directories form external 'world' to internal docker filesystem)

    set -e
    cd -- "$(dirname "$0")" # this script dir (not set on doubleclick)
    source ../../.env
    if [ ! "$(docker ps | grep node-cmd)" ] 
      docker build -t node-cmd .
      docker rm -f node-cmd |:
      docker run -d --name node-cmd -p 4200:4200 -p 4201:4201 -p 3002:3002 -p 3003:3003 -p 3004:3004 -v $toolsdir/node-cmd/logs:/root/.npm/_logs -v $workdir:/work node-cmd

  • ok now you can add some project e.g. work/code/myProject and add to it following file 'run-cmd' (must be executable)

    cd -- "$(dirname "$0")"
    docker exec -it node-cmd bash -c "cd /work/code/myProject; bash"

  • then if you run above script (by double-click), you will see console with available node commands in project directory e.g. npm install

  • to run project in background (e.g some serwice) e.g. run web-server angular-cli application you can use following script (named run-front -must be executable) - (you must also edit /etc/hosts file to add proper domain)

    cd -- "$(dirname "$0")"
    open "http://my-angular.local:3002"
    docker exec -it node-cmd  /bin/sh -c "cd /work/code/my-angular-project; npm start"
    cat         # for block script and wait for user ctrl+C

Downloading and unzipping a .zip file without writing to disk

Use the zipfile module. To extract a file from a URL, you'll need to wrap the result of a urlopen call in a BytesIO object. This is because the result of a web request returned by urlopen doesn't support seeking:

from urllib.request import urlopen

from io import BytesIO
from zipfile import ZipFile

zip_url = ''

with urlopen(zip_url) as f:
    with BytesIO( as b, ZipFile(b) as myzipfile:
        foofile ='foo.txt')

If you already have the file downloaded locally, you don't need BytesIO, just open it in binary mode and pass to ZipFile directly:

from zipfile import ZipFile

zip_filename = ''

with open(zip_filename, 'rb') as f:
    with ZipFile(f) as myzipfile:
        foofile ='foo.txt')

Again, note that you have to open the file in binary ('rb') mode, not as text or you'll get a zipfile.BadZipFile: File is not a zip file error.

It's good practice to use all these things as context managers with the with statement, so that they'll be closed properly.

Exception thrown in catch and finally clause

Exceptions in the finally block supersede exceptions in the catch block.

Java Language Specification:

If the catch block completes abruptly for reason R, then the finally block is executed. Then there is a choice:

  • If the finally block completes normally, then the try statement completes abruptly for reason R.

  • If the finally block completes abruptly for reason S, then the try statement completes abruptly for reason S (and reason R is discarded).

Trying to detect browser close event

As Phoenix said, use jQuery .bind method, but for more browser compatibility you should return a String,

    $(window).bind("beforeunload", function() { 
        return "Do you really want to close?"; 

more details can be found at :

Set value to currency in <input type="number" />

You guys are completely right numbers can only go in the numeric field. I use the exact same thing as already listed with a bit of css styling on a span tag:

<span>$</span><input type="number" min="0.01" step="0.01" max="2500" value="25.67">

Then add a bit of styling magic:


recursively use scp but excluding some folders

If you use a pem file to authenticate u can use the following command (which will exclude files with something extension):

rsync -Lavz -e "ssh -i <full-path-to-pem> -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null" --exclude "*.something" --progress <path inside local host> <user>@<host>:<path inside remote host>

The -L means follow links (copy files not links). Use full path to your pem file and not relative.

Using sshfs is not recommended since it works slowly. Also, the combination of find and scp that was presented above is also a bad idea since it will open a ssh session per file which is too expensive.

How do I send a file in Android from a mobile device to server using http?

Easy, you can use a Post request and submit your file as binary (byte array).

String url = "http://yourserver";
File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath(),
try {
    HttpClient httpclient = new DefaultHttpClient();

    HttpPost httppost = new HttpPost(url);

    InputStreamEntity reqEntity = new InputStreamEntity(
            new FileInputStream(file), -1);
    reqEntity.setChunked(true); // Send in multiple parts if needed
    HttpResponse response = httpclient.execute(httppost);
    //Do something with response...

} catch (Exception e) {
    // show error

What is the difference between response.sendRedirect() and request.getRequestDispatcher().forward(request,response)

To simply explain the difference,


doesn't prepend the contextpath (refers to the application/module in which the servlet is bundled)

but, whereas

 request.getRequestDispathcer("login.jsp").forward(request, response);

will prepend the contextpath of the respective application

Furthermore, Redirect request is used to redirect to resources to different servers or domains. This transfer of control task is delegated to the browser by the container. That is, the redirect sends a header back to the browser / client. This header contains the resource url to be redirected by the browser. Then the browser initiates a new request to the given url.

Forward request is used to forward to resources available within the server from where the call is made. This transfer of control is done by the container internally and browser / client is not involved.

git checkout all the files

If you want to checkout all the files 'anywhere'

git checkout -- $(git rev-parse --show-toplevel)

How to put a jpg or png image into a button in HTML

Use <button> element instead of <input type=button />

PHP Parse HTML code

Use PHP Document Object Model:

   $str = '<h1>T1</h1>Lorem ipsum.<h1>T2</h1>The quick red fox...<h1>T3</h1>... jumps over the lazy brown FROG';
   $DOM = new DOMDocument;

   //get all H1
   $items = $DOM->getElementsByTagName('h1');

   //display all H1 text
   for ($i = 0; $i < $items->length; $i++)
        echo $items->item($i)->nodeValue . "<br/>";

This outputs as:


[EDIT]: After OP Clarification:

If you want the content like Lorem ipsum. etc, you can directly use this regex:

   $str = '<h1>T1</h1>Lorem ipsum.<h1>T2</h1>The quick red fox...<h1>T3</h1>... jumps over the lazy brown FROG';
   echo preg_replace("#<h1.*?>.*?</h1>#", "", $str);

this outputs:

Lorem ipsum.The quick red fox...... jumps over the lazy brown FROG

Skip rows during csv import pandas

Also be sure that your file is actually a CSV file. For example, if you had an .xls file, and simply changed the file extension to .csv, the file won't import and will give the error above. To check to see if this is your problem open the file in excel and it will likely say:

"The file format and extension of 'Filename.csv' don't match. The file could be corrupted or unsafe. Unless you trust its source, don't open it. Do you want to open it anyway?"

To fix the file: open the file in Excel, click "Save As", Choose the file format to save as (use .cvs), then replace the existing file.

This was my problem, and fixed the error for me.

How to resolve git stash conflict without commit?

git stash branch will works, which creates a new branch for you, checks out the commit you were on when you stashed your work, reapplies your work there, and then drops the stash if it applies successfully. check this

How to write string literals in python without having to escape them?

You will find Python's string literal documentation here:

and here:

The simplest example would be using the 'r' prefix:

ss = r'Hello\nWorld'

How to "wait" a Thread in Android

You need the sleep method of the Thread class.

public static void sleep (long time)

Causes the thread which sent this message to sleep for the given interval of time (given in milliseconds). The precision is not guaranteed - the Thread may sleep more or less than requested.


time The time to sleep in milliseconds.

Difference between final and effectively final

Declaring a variable final or not declaring it final, but keeping it effectively final may result (depends on compiler) in different bytecode.

Let's have a look on a small example:

    public static void main(String[] args) {
        final boolean i = true;   // 6  // final by declaration
        boolean j = true;         // 7  // effectively final

        if (i) {                  // 9
            System.out.println(i);// 10
        if (!i) {                 // 12
            System.out.println(i);// 13
        if (j) {                  // 15
            System.out.println(j);// 16
        if (!j) {                 // 18
            System.out.println(j);// 19

The corresponding bytecode of the main method (Java 8u161 on Windows 64 Bit):

  public static void main(java.lang.String[]);
       0: iconst_1
       1: istore_1
       2: iconst_1
       3: istore_2
       4: getstatic     #16                 // Field java/lang/System.out:Ljava/io/PrintStream;
       7: iconst_1
       8: invokevirtual #22                 // Method java/io/PrintStream.println:(Z)V
      11: iload_2
      12: ifeq          22
      15: getstatic     #16                 // Field java/lang/System.out:Ljava/io/PrintStream;
      18: iload_2
      19: invokevirtual #22                 // Method java/io/PrintStream.println:(Z)V
      22: iload_2
      23: ifne          33
      26: getstatic     #16                 // Field java/lang/System.out:Ljava/io/PrintStream;
      29: iload_2
      30: invokevirtual #22                 // Method java/io/PrintStream.println:(Z)V
      33: return

The corresponding line number table:

   line 6: 0
   line 7: 2
   line 10: 4
   line 15: 11
   line 16: 15
   line 18: 22
   line 19: 26
   line 21: 33

As we see the source code at lines 12, 13, 14 doesn't appear in the byte code. That's because i is true and will not change it's state. Thus this code is unreachable (more in this answer). For the same reason the code at line 9 misses too. The state of i doesn't have to be evaluated since it is true for sure.

On the other hand though the variable j is effectively final it's not processed in the same way. There are no such optimizations applied. The state of j is evaluated two times. The bytecode is the same regardless of j being effectively final.

How to check compiler log in sql developer?

I can also use

show errors;

In sql worksheet.

Error: "dictionary update sequence element #0 has length 1; 2 is required" on Django 1.4

Here is how I encountered this error in Django and fixed it:

Code with error

urlpatterns = [path('home/', views.home, 'home'),]


urlpatterns = [path('home/', views.home, name='home'),]

Find maximum value of a column and return the corresponding row values using Pandas


This will return the entire row with max value

jQuery to remove an option from drop down list, given option's text/value

Once you have localized the dropdown element

dropdownElement = $("#dropdownElement");

Find the <option> element using the JQuery attribute selector


src absolute path problem

You should be referencing it as localhost. Like this:

<img src="http:\\localhost\site\img\mypicture.jpg"/>

Could not load the Tomcat server configuration

A quick solution in eclipse to resolve when Tomcat could not load as per the following error: Tomcat Error

Just refresh the Tomcat folder should do the trick. If it still does not work, delete all files in eclipse under the Tomcat folder, re-copy the server files then refresh the Tomcat folder. Tomcat should restart correctly after that.

Refresh Tomcat folder

Get current value when change select option - Angular2

You can Use ngValue. ngValue passes sting and object both.

Pass as Object:

<select (change)="onItemChange($event.value)">
    <option *ngFor="#obj of arr" [ngValue]="obj.value">

Pass as String:

<select (change)="onItemChange($event.value)">
    <option *ngFor="#obj of arr" [ngValue]="obj">

How do you automatically set the focus to a textbox when a web page loads?

If you're using jquery:

$(function() {

or prototype:

Event.observe(window, 'load', function() {

or plain javascript:

window.onload = function() {

though keep in mind that this will replace other on load handlers, so look up addLoadEvent() in google for a safe way to append onload handlers rather than replacing.

what is an illegal reflective access

If you want to go with the add-open option, here's a command to find which module provides which package ->

java --list-modules | tr @ " " | awk '{ print $1 }' | xargs -n1 java -d

the name of the module will be shown with the @ while the name of the packages without it

NOTE: tested with JDK 11

IMPORTANT: obviously is better than the provider of the package does not do the illegal access

SQLite select where empty?

You can do this with the following:

int counter = 0;
String sql = "SELECT projectName,Owner " + "FROM Project WHERE Owner= ?";
PreparedStatement prep = conn.prepareStatement(sql);
prep.setString(1, "");
ResultSet rs = prep.executeQuery();
while ( {

This will give you the no of rows where the column value is null or blank.

JavaScript object: access variable property by name as string

You don't need a function for it - simply use the bracket notation:

var side = columns['right'];

This is equal to dot notation, var side = columns.right;, except the fact that right could also come from a variable, function return value, etc., when using bracket notation.

If you NEED a function for it, here it is:

function read_prop(obj, prop) {
    return obj[prop];

To answer some of the comments below that aren't directly related to the original question, nested objects can be referenced through multiple brackets. If you have a nested object like so:

var foo = { a: 1, b: 2, c: {x: 999, y:998, z: 997}};

you can access property x of c as follows:

var cx = foo['c']['x']

If a property is undefined, an attempt to reference it will return undefined (not null or false):

foo['c']['q'] === null
// returns false

foo['c']['q'] === false
// returns false

foo['c']['q'] === undefined
// returns true

ExecutorService that interrupts tasks after a timeout

It seems problem is not in JDK bug 6602600 ( it was solved at 2010-05-22), but in incorrect call of sleep(10) in circle. Addition note, that the main Thread must give directly CHANCE to other threads to realize thier tasks by invoke SLEEP(0) in EVERY branch of outer circle. It is better, I think, to use Thread.yield() instead of Thread.sleep(0)

The result corrected part of previous problem code is such like this:


if (i % 1000== 0) {
System.out.println(i + "/" + counter.get()+ "/"+service.toString());

//                while (i > counter.get()) {
//                    Thread.sleep(10);
//                } 

It works correctly with amount of outer counter up to 150 000 000 tested circles.

Create an ArrayList of unique values

 //Saving each element of the input file in an arraylist 
    ArrayList<String> list = new ArrayList<String>();
    while (s.hasNext()){

//That's all you need
list = (ArrayList);

Maven: How to run a .java file from command line passing arguments

Adding a shell script e.g. makes it much more easier:

#!/usr/bin/env bash
export JAVA_PROGRAM_ARGS=`echo "$@"`
mvn exec:java -Dexec.mainClass="test.Main" -Dexec.args="$JAVA_PROGRAM_ARGS"

Then you are able to execute:

./ arg1 arg2 arg3

Synchronous XMLHttpRequest warning and <script>

In my case if i append script tag like this :

var script = document.createElement('script');
script.src = 'url/test.js';

i get that warning but if i append script tag to head first then change src warning gone !

var script = document.createElement('script');
script.src = 'url/test.js';

works fine!!

Static Vs. Dynamic Binding in Java

Because the compiler knows the binding at compile time. If you invoke a method on an interface, for example, then the compiler can't know and the binding is resolved at runtime because the actual object having a method invoked on it could possible be one of several. Therefore that is runtime or dynamic binding.

Your invocation is bound to the Animal class at compile time because you've specified the type. If you passed that variable into another method somewhere else, noone would know (apart from you because you wrote it) what actual class it would be. The only clue is the declared type of Animal.

Calculate relative time in C#

jquery.timeago plugin

Jeff, because Stack Overflow uses jQuery extensively, I recommend the jquery.timeago plugin.


  • Avoid timestamps dated "1 minute ago" even though the page was opened 10 minutes ago; timeago refreshes automatically.
  • You can take full advantage of page and/or fragment caching in your web applications, because the timestamps aren't calculated on the server.
  • You get to use microformats like the cool kids.

Just attach it to your timestamps on DOM ready:

jQuery(document).ready(function() {

This will turn all abbr elements with a class of timeago and an ISO 8601 timestamp in the title:

<abbr class="timeago" title="2008-07-17T09:24:17Z">July 17, 2008</abbr>

into something like this:

<abbr class="timeago" title="July 17, 2008">4 months ago</abbr>

which yields: 4 months ago. As time passes, the timestamps will automatically update.

Disclaimer: I wrote this plugin, so I'm biased.

Font Awesome & Unicode

In latest 5.13 there's a difference. You do like always...

font-family: "Font Awesome 5 Free";
content: "\f107";

But there's a difference now... Instead of use font-weight: 500; You are following this:

font-family: "Font Awesome 5 Free";
font-weight: 900;
content: "\f107";

Why is that? I figure out by finding in in .fas class, so you can figure out an updated way by looking into .fas class so you're doing the same as it has to be. Figure out if there's a font-weight and font-family. Here you go guys. That's an update answer for 5.13.

Add st, nd, rd and th (ordinal) suffix to a number

The rules are as follows:

  • st is used with numbers ending in 1 (e.g. 1st, pronounced first)
  • nd is used with numbers ending in 2 (e.g. 92nd, pronounced ninety-second)
  • rd is used with numbers ending in 3 (e.g. 33rd, pronounced thirty-third)
  • As an exception to the above rules, all the "teen" numbers ending with 11, 12 or 13 use -th (e.g. 11th, pronounced eleventh, 112th, pronounced one hundred [and] twelfth)
  • th is used for all other numbers (e.g. 9th, pronounced ninth).

The following JavaScript code (rewritten in Jun '14) accomplishes this:

function ordinal_suffix_of(i) {
    var j = i % 10,
        k = i % 100;
    if (j == 1 && k != 11) {
        return i + "st";
    if (j == 2 && k != 12) {
        return i + "nd";
    if (j == 3 && k != 13) {
        return i + "rd";
    return i + "th";

Sample output for numbers between 0-115:

  0  0th
  1  1st
  2  2nd
  3  3rd
  4  4th
  5  5th
  6  6th
  7  7th
  8  8th
  9  9th
 10  10th
 11  11th
 12  12th
 13  13th
 14  14th
 15  15th
 16  16th
 17  17th
 18  18th
 19  19th
 20  20th
 21  21st
 22  22nd
 23  23rd
 24  24th
 25  25th
 26  26th
 27  27th
 28  28th
 29  29th
 30  30th
 31  31st
 32  32nd
 33  33rd
 34  34th
 35  35th
 36  36th
 37  37th
 38  38th
 39  39th
 40  40th
 41  41st
 42  42nd
 43  43rd
 44  44th
 45  45th
 46  46th
 47  47th
 48  48th
 49  49th
 50  50th
 51  51st
 52  52nd
 53  53rd
 54  54th
 55  55th
 56  56th
 57  57th
 58  58th
 59  59th
 60  60th
 61  61st
 62  62nd
 63  63rd
 64  64th
 65  65th
 66  66th
 67  67th
 68  68th
 69  69th
 70  70th
 71  71st
 72  72nd
 73  73rd
 74  74th
 75  75th
 76  76th
 77  77th
 78  78th
 79  79th
 80  80th
 81  81st
 82  82nd
 83  83rd
 84  84th
 85  85th
 86  86th
 87  87th
 88  88th
 89  89th
 90  90th
 91  91st
 92  92nd
 93  93rd
 94  94th
 95  95th
 96  96th
 97  97th
 98  98th
 99  99th
100  100th
101  101st
102  102nd
103  103rd
104  104th
105  105th
106  106th
107  107th
108  108th
109  109th
110  110th
111  111th
112  112th
113  113th
114  114th
115  115th


In this approach only one statement is executed when the UPDATE is successful.

-- For each row in source

UPDATE target
SET <target_columns> = <source_values>
WHERE <target_expression>

   INSERT target (<target_columns>)
VALUES (<source_values>)


Anaconda / Python: Change Anaconda Prompt User Path

If you want to access folder you specified using Anaconda Prompt, try typing

cd C:\Users\u354590

TypeError: coercing to Unicode: need string or buffer

For the less specific case (not just the code in the question - since this is one of the first results in Google for this generic error message. This error also occurs when running certain os command with None argument.

For example:


Will raise this exception when arg is None.

Call break in nested if statements

In the most languages, break does only cancel loops like for, while etc.

How to determine the version of android SDK installed in computer?

You can check following path for Windows 10


Also, you can check from android studio

File > Project Structure > SDK Location > Android SDK Location

How do I get milliseconds from epoch (1970-01-01) in Java?

You can also try

  Calendar calendar = Calendar.getInstance();

getTimeInMillis() - the current time as UTC milliseconds from the epoch

How to find the installed pandas version


pip freeze

It works the same as above.

pip show pandas

Displays information about a specific package. For more information, check out pip help

Making a UITableView scroll when text field is selected

I just looked again into the iOS 5.0 lib reference and found this section titled "Moving Content That Is Located Under the Keyboard": TextAndWebiPhoneOS KeyboardManagement

Is this new since iOS 5, perhaps? I haven't read into it yet as I'm in the middle of something else, but perhaps others know more and can enlighten me and others here.

Does the Apple doc supersede what's been discussed here or is the information here still useful to iOS 5 SDK users?

Access images inside public folder in laravel

In my case it worked perfectly

<img style="border-radius: 50%;height: 50px;width: 80px;"  src="<?php echo asset("storage/TeacherImages/{$teacher->profilePic}")?>">

this is used to display image from folder i hope this will help someone looking for this type of code

javascript: optional first argument in function

There are 2 ways to do this.


function something(options) {
    var timeToLive = options.timeToLive || 200; // default to 200 if not set


function something(timeToDie /*, timeToLive*/) {
    var timeToLive = arguments[1] || 200; // default to 200 if not set

In 1), options is a JS object with what ever attributes are required. This is easier to maintain and extend.

In 2), the function signature is clear to read and understand that a second argument can be provided. I've seen this style used in Mozilla code and documentation.

String's Maximum length in Java - calling length() method

The Return type of the length() method of the String class is int.

public int length()


So the maximum value of int is 2147483647.

String is considered as char array internally,So indexing is done within the maximum range. This means we cannot index the 2147483648th member.So the maximum length of String in java is 2147483647.

Primitive data type int is 4 bytes(32 bits) in java.As 1 bit (MSB) is used as a sign bit,The range is constrained within -2^31 to 2^31-1 (-2147483648 to 2147483647). We cannot use negative values for indexing.So obviously the range we can use is from 0 to 2147483647.

Passing ArrayList through Intent

Suppose you need to pass an arraylist of following class from current activity to next activity // class of the objects those in the arraylist // remember to implement the class from Serializable interface // Serializable means it converts the object into stream of bytes and helps to transfer that object

public class Question implements Serializable {

in your current activity you probably have an ArrayList as follows

ArrayList<Question> qsList = new ArrayList<>();
qsList.add(new Question(1));
qsList.add(new Question(2));
qsList.add(new Question(3));

// intialize Bundle instance
Bundle b = new Bundle();
// putting questions list into the bundle .. as key value pair.
// so you can retrieve the arrayList with this key
b.putSerializable("questions", (Serializable) qsList);
Intent i = new Intent(CurrentActivity.this, NextActivity.class);

in order to get the arraylist within the next activity

//get the bundle
Bundle b = getIntent().getExtras();
//getting the arraylist from the key
ArrayList<Question> q = (ArrayList<Question>) b.getSerializable("questions");

How do I include negative decimal numbers in this regular expression?

This worked for me, allowing both negative and positive numbers:


If using C#:

Regex.Match(someString, @"\-*\d+").Value;

Sharing a URL with a query string on Twitter

Twitter now lets you send the URL through a data attribute. This works great for me:

<a href="javascript:;" class="twitter-share-button" data-lang="en" data-text="check out link b" data-url="">Tweet</a>

Why is it important to override GetHashCode when Equals method is overridden?

Yes, it is important if your item will be used as a key in a dictionary, or HashSet<T>, etc - since this is used (in the absence of a custom IEqualityComparer<T>) to group items into buckets. If the hash-code for two items does not match, they may never be considered equal (Equals will simply never be called).

The GetHashCode() method should reflect the Equals logic; the rules are:

  • if two things are equal (Equals(...) == true) then they must return the same value for GetHashCode()
  • if the GetHashCode() is equal, it is not necessary for them to be the same; this is a collision, and Equals will be called to see if it is a real equality or not.

In this case, it looks like "return FooId;" is a suitable GetHashCode() implementation. If you are testing multiple properties, it is common to combine them using code like below, to reduce diagonal collisions (i.e. so that new Foo(3,5) has a different hash-code to new Foo(5,3)):

unchecked // only needed if you're compiling with arithmetic checks enabled
{ // (the default compiler behaviour is *disabled*, so most folks won't need this)
    int hash = 13;
    hash = (hash * 7) + field1.GetHashCode();
    hash = (hash * 7) + field2.GetHashCode();
    return hash;

Oh - for convenience, you might also consider providing == and != operators when overriding Equals and GetHashCode.

A demonstration of what happens when you get this wrong is here.

How do I find which process is leaking memory?

As suggeseted, the way to go is valgrind. It's a profiler that checks many aspects of the running performance of your application, including the usage of memory.

Running your application through Valgrind will allow you to verify if you forget to release memory allocated with malloc, if you free the same memory twice etc.

How to get data by SqlDataReader.GetValue by column name

thisReader.GetString(int columnIndex)

Java SSLHandshakeException "no cipher suites in common"

In my case, I got this no cipher suites in common error because I've loaded a p12 format file to the keystore of the server, instead of a jks file.

Android: How to stretch an image to the screen width while maintaining aspect ratio?

Its simple matter of setting adjustViewBounds="true" and scaleType="fitCenter" in the XML file for the ImageView!



Note: layout_width is set to match_parent

Explanation of the UML arrows

Here's some explanations from the Visual Studio 2015 docs:

UML Class Diagrams: Reference:

UML class diagram

5: Association: A relationship between the members of two classifiers.

5a: Aggregation: An association representing a shared ownership relationship. The Aggregation property of the owner role is set to Shared.

5b: Composition: An association representing a whole-part relationship. The Aggregation property of the owner role is set to Composite.

9: Generalization: The specific classifier inherits part of its definition from the general classifier. The general classifier is at the arrow end of the connector. Attributes, associations, and operations are inherited by the specific classifier. Use the Inheritance tool to create a generalization between two classifiers.

Package diagram

13: Import: A relationship between packages, indicating that one package includes all the definitions of another.

14: Dependency: The definition or implementation of the dependent classifier might change if the classifier at the arrowhead end is changed.

Realization relationship

15: Realization: The class implements the operations and attributes defined by the interface. Use the Inheritance tool to create a realization between a class and an interface.

16: Realization: An alternative presentation of the same relationship. The label on the lollipop symbol identifies the interface.

UML Class Diagrams: Guidelines:

Properties of an Association

Aggregation: This appears as a diamond shape at one end of the connector. You can use it to indicate that instances at the aggregating role own or contain instances of the other.

Is Navigable: If true for only one role, an arrow appears in the navigable direction. You can use this to indicate navigability of links and database relations in the software.

Generalization: Generalization means that the specializing or derived type inherits attributes, operations, and associations of the general or base type. The general type appears at the arrowhead end of the relationship.

Realization: Realization means that a class implements the attributes and operations specified by the interface. The interface is at the arrow end of the connector.

Let me know if you have more questions.

AngularJS : How to watch service variables?

Have a look at this plunker:: this is the simplest example i could think of

<div ng-app="myApp">
    <div ng-controller="FirstCtrl">
        <input type="text" ng-model="Data.FirstName"><!-- Input entered here -->
        <br>Input is : <strong>{{Data.FirstName}}</strong><!-- Successfully updates here -->
    <div ng-controller="SecondCtrl">
        Input should also be here: {{Data.FirstName}}<!-- How do I automatically updated it here? -->

// declare the app with no dependencies
var myApp = angular.module('myApp', []);
myApp.factory('Data', function(){
   return { FirstName: '' };

myApp.controller('FirstCtrl', function( $scope, Data ){
    $scope.Data = Data;

myApp.controller('SecondCtrl', function( $scope, Data ){
    $scope.Data = Data;

How to clear textarea on click?

You can use the placeholder attribute introduced in HTML5:

<textarea placeholder="Please describe why"></textarea>

This will place your filler text in grey that will disappear automatically when a user clicks on the text field. Additionally, it will reappear if it loses focus and the text area is blank.

Doing HTTP requests FROM Laravel to an external API

You just want to call an external URL and use the results? PHP does this out of the box, if we're talking about a simple GET request to something serving JSON:

$json = json_decode(file_get_contents(''), true);

If you want to do a post request, it's a little harder but there's loads of examples how to do this with curl.

So I guess the question is; what exactly do you want?

Spring MVC Multipart Request with JSON

As documentation says:

Raised when the part of a "multipart/form-data" request identified by its name cannot be found.

This may be because the request is not a multipart/form-data either because the part is not present in the request, or because the web application is not configured correctly for processing multipart requests -- e.g. no MultipartResolver.

How do I fix MSB3073 error in my post-build event?

I was getting this error after downloading some source code from Github. Specifically the rust oxide development framework. My problem is that the Steam.ps1 script file, that's used to update some of the dlls from Steam was blocked by the OS. I had to open the files properties an UNBLOCK it. I had not realized this was done to ps1 files as well as exes.

Style disabled button with CSS

consider the following solution

  pointer-events: none; 
  background-color: #edf1f2;

How to install sshpass on mac?

Some years have passed and there is now a proper Homebrew Tap for sshpass, maintained by Aleks Hudochenkov. To install sshpass from this tap, run:

brew install hudochenkov/sshpass/sshpass

What is the best way to do a substring in a batch file?

Nicely explained above!

For all those who may suffer like me to get this working in a localized Windows (mine is XP in Slovak), you may try to replace the % with a !


SET TEXT=Hello World

Get docker container id from container name

In my case I was running Tensorflow Docker container in Ubuntu 20.04 :Run your docker container in One terminal , I ran it with

docker run -it od

And then started another terminal and ran below docker ps with sudo:

sudo docker ps

I successfully got container id:

CONTAINER ID        IMAGE               COMMAND             CREATED             
STATUS              PORTS               NAMES
e4ca1ad20b84        od                  "/bin/bash"         18 minutes ago      
Up 18 minutes                           unruffled_stonebraker

Can Twitter Bootstrap alerts fade in as well as out?

None of the current answers worked for me. I'm using Bootstrap 3.

I liked what Rob Vermeer was doing and started from his response.

For a fade in and then fade out effect, I just used wrote the following function and used jQuery:

Html on my page to add the alert(s) to:

        <div class="alert-messages text-center">

Javascript function to show and dismiss the alert.

function showAndDismissAlert(type, message) {
    var htmlAlert = '<div class="alert alert-' + type + '">' + message + '</div>';

    // Prepend so that alert is on top, could also append if we want new alerts to show below instead of on top.

    // Since we are prepending, take the first alert and tell it to fade in and then fade out.
    // Note: if we were appending, then should use last() instead of first()
    $(".alert-messages .alert").first().hide().fadeIn(200).delay(2000).fadeOut(1000, function () { $(this).remove(); });

Then, to show and dismiss the alert, just call the function like this:

    showAndDismissAlert('success', 'Saved Successfully!');
    showAndDismissAlert('danger', 'Error Encountered');
    showAndDismissAlert('info', 'Message Received');

As a side note, I styled the div.alert-messages fixed on top:

    div.alert-messages {
        position: fixed;
        top: 50px;
        left: 25%;
        right: 25%;
        z-index: 7000;

Installed SSL certificate in certificate store, but it's not in IIS certificate list

If you are using Godaddy as your certificate authority, and you are running into this issue; All you have to do is Re-key the certificate. I tried the above certutil -repairstore my "paste the serial # in here" but the system wanted me to use smart card for authentication. (Running IIS10 on Server 2016 and 2012R2)

When I Created a Certificate Request, gone through the process of Re-keying and gone through the process of "Complete Certificate Request" I was able to sucessfuly configure "Bindings..." without the certificate disappearing.

How does Facebook disable the browser's integrated Developer Tools?

I located the Facebook's console buster script using Chrome developer tools. Here is the script with minor changes for readability. I have removed the bits that I could not understand:

Object.defineProperty(window, "console", {
    value: console,
    writable: false,
    configurable: false

var i = 0;
function showWarningAndThrow() {
    if (!i) {
        setTimeout(function () {
            console.log("%cWarning message", "font: 2em sans-serif; color: yellow; background-color: red;");
        }, 1);
        i = 1;
    throw "Console is disabled";

var l, n = {
        set: function (o) {
            l = o;
        get: function () {
            return l;
Object.defineProperty(console, "_commandLineAPI", n);
Object.defineProperty(console, "__commandLineAPI", n);

With this, the console auto-complete fails silently while statements typed in console will fail to execute (the exception will be logged).


Is there Unicode glyph Symbol to represent "Search"

Displayed correct at Chrome OS - screenshots from this system.

tibetan astrological sign sgra gcan -char rtags U+0F17 ? U+0F17

telephone recorder (U+2315) ? U+2315

lepcha letter gla (U+1C04) ? U+1C04

Sending an Intent to browser to open specific URL

Is there also a way to pass coords directly to google maps to display?

You can use the geo URI prefix:

Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setData(Uri.parse("geo:" + latitude + "," + longitude));

Error: the entity type requires a primary key

Yet another reason may be that your entity class has several properties named somhow /.*id/i - so ending with ID case insensitive AND elementary type AND there is no [Key] attribute.

EF will namely try to figure out the PK by itself by looking for elementary typed properties ending in ID.

See my case:

public class MyTest, IMustHaveTenant
  public long Id { get; set; }
  public int TenantId { get; set; }
  public virtual string Signum{ get; set; }
  public virtual string ID { get; set; }
  public virtual string ID_Other { get; set; }

don't ask - lecacy code. The Id was even inherited, so I could not use [Key] (just simplifying the code here)

But here EF is totally confused.

What helped was using modelbuilder this in DBContext class.

            modelBuilder.Entity<MyTest>(f =>
                f.HasKey(e => e.Id);
                f.HasIndex(e => new { e.TenantId });
                f.HasIndex(e => new { e.TenantId, e.ID_Other });

the index on PK is implicit.

regular expression: match any word until first space

for the entire line


Loop through files in a folder in matlab

Looping through all the files in the folder is relatively easy:

files = dir('*.csv');
for file = files'
    csv = load(;
    % Do some stuff

How to kill a child process by the parent process?

In the parent process, fork()'s return value is the process ID of the child process. Stuff that value away somewhere for when you need to terminate the child process. fork() returns zero(0) in the child process.

When you need to terminate the child process, use the kill(2) function with the process ID returned by fork(), and the signal you wish to deliver (e.g. SIGTERM).

Remember to call wait() on the child process to prevent any lingering zombies.

Get name of object or class

Try this:

var classname = ("" + obj.constructor).split("function ")[1].split("(")[0];

How to check if a registry value exists using C#?

Of course, "Fagner Antunes Dornelles" is correct in its answer. But it seems to me that it is worth checking the registry branch itself in addition, or be sure of the part that is exactly there.

For example ("dirty hack"), i need to establish trust in the RMS infrastructure, otherwise when i open Word or Excel documents, i will be prompted for "Active Directory Rights Management Services". Here's how i can add remote trust to me servers in the enterprise infrastructure.

foreach (var strServer in listServer)
        RegistryKey regCurrentUser = Registry.CurrentUser.OpenSubKey($"Software\\Classes\\Local Settings\\Software\\Microsoft\\MSIPC\\{strServer}", false);
        if (regCurrentUser == null)
            throw new ApplicationException("Not found registry SubKey ...");
        if (regCurrentUser.GetValueNames().Contains("UserConsent") == false)
            throw new ApplicationException("Not found value in SubKey ...");
    catch (ApplicationException appEx)
            RegistryKey regCurrentUser = Registry.CurrentUser.OpenSubKey($"Software\\Classes\\Local Settings\\Software\\Microsoft\\MSIPC", true);
            RegistryKey newKey = regCurrentUser.CreateSubKey(strServer, true);
            newKey.SetValue("UserConsent", 1, RegistryValueKind.DWord);
        catch(Exception ex)
            Console.WriteLine($"{ex} Pipec kakoito ...");

Why is python saying invalid command 'bdist_wheel' on Travis CI?

Not related to Travis CI but I ran into similar problem trying to install jupyter on my Mac OSX 10.8.5, and none of the other answers was of help. The problem was caused by building the "wheel" for the package called pyzmq, with error messages filling hundreds of pages.

The solution I found was to directly install an older version of that package:

python -m pip install pyzmq==17 --user

After that, the installation of jupyter succeded without errors.

check android application is in foreground or not?

I don't understand what you want, but You can detect currently foreground/background application with ActivityManager.getRunningAppProcesses() call.

Something like,

class ForegroundCheckTask extends AsyncTask<Context, Void, Boolean> {

  protected Boolean doInBackground(Context... params) {
    final Context context = params[0].getApplicationContext();
    return isAppOnForeground(context);

  private boolean isAppOnForeground(Context context) {
    ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
    List<RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();
    if (appProcesses == null) {
      return false;
    final String packageName = context.getPackageName();
    for (RunningAppProcessInfo appProcess : appProcesses) {
      if (appProcess.importance == RunningAppProcessInfo.IMPORTANCE_FOREGROUND && appProcess.processName.equals(packageName)) {
        return true;
    return false;

// Use like this:
boolean foregroud = new ForegroundCheckTask().execute(context).get();

Also let me know if I misunderstand..

UPDATE: Look at this SO question Determining the current foreground application from a background task or service fore more information..


Disable and later enable all table indexes in Oracle

If you're on Oracle 11g, you may also want to check out dbms_index_utl.

Best way to do Version Control for MS Excel

I have been looking into this too. It apears that the latest Team Foundation Server 2010 may have an Excel Add-In.

Here is a clue:

How to list the files inside a JAR file?

I would like to expand on acheron55's answer, since it is a very non-safe solution, for several reasons:

  1. It doesn't close the FileSystem object.
  2. It doesn't check if the FileSystem object already exists.
  3. It isn't thread-safe.

This is somewhat a safer solution:

private static ConcurrentMap<String, Object> locks = new ConcurrentHashMap<>();

public void walk(String path) throws Exception {

    URI uri = getClass().getResource(path).toURI();
    if ("jar".equals(uri.getScheme()) {
        safeWalkJar(path, uri);
    } else {

private void safeWalkJar(String path, URI uri) throws Exception {

    synchronized (getLock(uri)) {    
        // this'll close the FileSystem object at the end
        try (FileSystem fs = getFileSystem(uri)) {

private Object getLock(URI uri) {

    String fileName = parseFileName(uri);  
    locks.computeIfAbsent(fileName, s -> new Object());
    return locks.get(fileName);

private String parseFileName(URI uri) {

    String schemeSpecificPart = uri.getSchemeSpecificPart();
    return schemeSpecificPart.substring(0, schemeSpecificPart.indexOf("!"));

private FileSystem getFileSystem(URI uri) throws IOException {

    try {
        return FileSystems.getFileSystem(uri);
    } catch (FileSystemNotFoundException e) {
        return FileSystems.newFileSystem(uri, Collections.<String, String>emptyMap());

There's no real need to synchronize over the file name; one could simply synchronize on the same object every time (or make the method synchronized), it's purely an optimization.

I would say that this is still a problematic solution, since there might be other parts in the code that use the FileSystem interface over the same files, and it could interfere with them (even in a single threaded application).
Also, it doesn't check for nulls (for instance, on getClass().getResource().

This particular Java NIO interface is kind of horrible, since it introduces a global/singleton non thread-safe resource, and its documentation is extremely vague (a lot of unknowns due to provider specific implementations). Results may vary for other FileSystem providers (not JAR). Maybe there's a good reason for it being that way; I don't know, I haven't researched the implementations.

Extracting specific columns in numpy array

I assume you wanted columns 1 and 9?

To select multiple columns at once, use

X = data[:, [1, 9]]

To select one at a time, use

x, y = data[:, 1], data[:, 9]

With names:

data[:, ['Column Name1','Column Name2']]

You can get the names from data.dtype.names

Unable to cast object of type 'System.DBNull' to type 'System.String`

You can use C#'s null coalescing operator

return accountNumber ?? string.Empty;

What are libtool's .la file for?

It is a textual file that includes a description of the library.

It allows libtool to create platform-independent names.

For example, libfoo goes to:

Under Linux:

/lib/       # Symlink to shared object
/lib/     # Symlink to shared object
/lib/ # Shared object
/lib/libfoo.a        # Static library
/lib/       # 'libtool' library

Under Cygwin:

/lib/libfoo.dll.a    # Import library
/lib/libfoo.a        # Static library
/lib/       # libtool library
/bin/cygfoo_1.dll    # DLL

Under Windows MinGW:

/lib/libfoo.dll.a    # Import library
/lib/libfoo.a        # Static library
/lib/       # 'libtool' library
/bin/foo_1.dll       # DLL

So is the only file that is preserved between platforms by libtool allowing to understand what happens with:

  • Library dependencies
  • Actual file names
  • Library version and revision

Without depending on a specific platform implementation of libraries.

When to use Hadoop, HBase, Hive and Pig?

Pig: it is better to handle files and cleaning data example: removing null values,string handling,unnecessary values Hive: for querying on cleaned data

Read all worksheets in an Excel workbook into an R list with data.frames

You can load the work book and then use lapply, getSheets and readWorksheet and do something like this.

wb.mtcars <- loadWorkbook(system.file("demoFiles/mtcars.xlsx", 
                          package = "XLConnect"))
sheet_names <- getSheets(wb.mtcars)
names(sheet_names) <- sheet_names

sheet_list <- lapply(sheet_names, function(.sheet){
    readWorksheet(object=wb.mtcars, .sheet)})

Where are include files stored - Ubuntu Linux, GCC

Karl answered your search-path question, but as far as the "source of the files" goes, one thing to be aware of is that if you install the libfoo package and want to do some development with it (i.e., use its headers), you will also need to install libfoo-dev. The standard library header files are already in /usr/include, as you saw.

Note that some libraries with a lot of headers will install them to a subdirectory, e.g., /usr/include/openssl. To include one of those, just provide the path without the /usr/include part, for example:

#include <openssl/aes.h>

Combine multiple Collections into a single logical Collection?

You could create a new List and addAll() of your other Lists to it. Then return an unmodifiable list with Collections.unmodifiableList().

No resource found - Theme.AppCompat.Light.DarkActionBar

Using Visual Studio 2015 (Windows7) + Xamarin had this error and after trying multiple things (installing packages, download ended removing the full Xamarin folder inside

C:\Users\<my user>\AppData\Local

After that, Rebuild the application in VS and errors disappeared.

How do I find the current machine's full hostname in C (hostname and domain information)?

gethostname() is POSIX way to get local host name. Check out man.

BSD function getdomainname() can give you domain name so you can build fully qualified hostname. There is no POSIX way to get a domain I'm afraid.

Setting public class variables

class Testclass
  public $testvar;

  function dosomething()
    echo $this->testvar;

$Testclass = new Testclass();
$Testclass->testvar = "another value";    
$Testclass->dosomething(); ////It will print "another value"

Creating PHP class instance with a string

You can simply use the following syntax to create a new class (this is handy if you're creating a factory):

$className = $whatever;
$object = new $className;

As an (exceptionally crude) example factory method:

public function &factory($className) {

    require_once($className . '.php');
    if(class_exists($className)) return new $className;

    die('Cannot create new "' . $className . '" class - includes not found or class unavailable.');

Express.js - app.listen vs server.listen

I came with same question but after google, I found there is no big difference :)

From Github

If you wish to create both an HTTP and HTTPS server you may do so with the "http" and "https" modules as shown here.

 * Listen for connections.
 * A node `http.Server` is returned, with this
 * application (which is a `Function`) as its
 * callback. If you wish to create both an HTTP
 * and HTTPS server you may do so with the "http"
 * and "https" modules as shown here:
 *    var http = require('http')
 *      , https = require('https')
 *      , express = require('express')
 *      , app = express();
 *    http.createServer(app).listen(80);
 *    https.createServer({ ... }, app).listen(443);
 * @return {http.Server}
 * @api public

app.listen = function(){
  var server = http.createServer(this);
  return server.listen.apply(server, arguments);

Also if you want to work with see their example

See this

I prefer app.listen() :)

Android. Fragment getActivity() sometimes returns null

Ok, I know that this question is actually solved but I decided to share my solution for this. I've created abstract parent class for my Fragment:

public abstract class ABaseFragment extends Fragment{

    protected IActivityEnabledListener aeListener;

    protected interface IActivityEnabledListener{
        void onActivityEnabled(FragmentActivity activity);

    protected void getAvailableActivity(IActivityEnabledListener listener){
        if (getActivity() == null){
            aeListener = listener;

        } else {

    public void onAttach(Activity activity) {

        if (aeListener != null){
            aeListener.onActivityEnabled((FragmentActivity) activity);
            aeListener = null;

    public void onAttach(Context context) {

        if (aeListener != null){
            aeListener.onActivityEnabled((FragmentActivity) context);
            aeListener = null;

As you can see, I've added a listener so, whenever I'll need to get Fragments Activity instead of standard getActivity(), I'll need to call

 getAvailableActivity(new IActivityEnabledListener() {
        public void onActivityEnabled(FragmentActivity activity) {
            // Do manipulations with your activity

Error You must specify a region when running command aws ecs list-container-instances

#1- Run this to configure the region once and for all:

aws configure set region us-east-1 --profile admin
  • Change admin next to the profile if it's different.

  • Change us-east-1 if your region is different.

#2- Run your command again:

aws ecs list-container-instances --cluster default

What's the most concise way to read query parameters in AngularJS?

To give a partial answer my own question, here is a working sample for HTML5 browsers:

<!DOCTYPE html>
<html ng-app="myApp">
  <script src=""></script>
    angular.module('myApp', [], function($locationProvider) {
    function QueryCntl($scope, $location) {
      $ = $['target'];
<body ng-controller="QueryCntl">

Target: {{target}}<br/>


The key was to call $locationProvider.html5Mode(true); as done above. It now works when opening I'm not happy about the fact that it won't work in older browsers, but I might use this approach anyway.

An alternative that would work with older browsers would be to drop the html5mode(true) call and use the following address with hash+slash instead:

The relevant documentation is at Developer Guide: Angular Services: Using $location (strange that my google search didn't find this...).

Consider defining a bean of type 'package' in your configuration [Spring-Boot]

You'll also get this error if you accidentally define the same bean in two different classes. That happened to me. The error message was misleading. When I removed the extra bean, the issue was resolved.

Maximum size for a SQL Server Query? IN clause? Is there a Better Approach

Per batch, 65536 * Network Packet Size which is 4k so 256 MB

However, IN will stop way before that but it's not precise.

You end up with memory errors but I can't recall the exact error. A huge IN will be inefficient anyway.

Edit: Remus reminded me: the error is about "stack size"

Process to convert simple Python script into Windows executable

You can create executable from python script using NSIS (Nullsoft scriptable install system). Follow the below steps to convert your python files to executable.

  • Download and install NSIS in your system.

  • Compress the folder in the .zip file that you want to export into the executable.

  • Start NSIS and select Installer based on ZIP file. Find and provide a path to your compressed file.

  • Provide your Installer Name and Default Folder path and click on Generate to generate your exe file.

  • Once its done you can click on Test to test executable or Close to complete the process.

  • The executable generated can be installed on the system and can be distributed to use this application without even worrying about installing the required python and its packages.

For a video tutorial follow: How to Convert any Python File to .EXE

How can I give the Intellij compiler more heap space?

GWT in Intellij 12

FWIW, I was getting a similar error with my GWT application during 'Build | Rebuild Project'.

This was caused by Intellij doing a full GWT compile which I didn't like because it is also a very lengthy process.

I disabled GWT compile by turning off the module check boxes under 'Project Structure | Facets | GWT'.

Alternatively there is a 'Compiler maximum heap size' setting in that location as well.

Git Bash is extremely slow on Windows 7 x64

While your problem might be network-based, I've personally sped up my local git status calls tenfold (7+ seconds down to 700 ms) by doing two modifications. This is on a 700 MB repository with 21,000 files and excessive numbers of large binary files.

One is enabling parallel index preloads. From a command prompt:

git config core.preloadindex true
This changed time git status from 7 seconds to 2.5 seconds.


The following is no longer necessary. A patch has fixed this as of mysysgit 1.9.4
However, you must enable the fix by typing
git config core.fscache true

I also disabled the UAC and the "luafv" driver (reboot required). This disables a driver in Windows Vista, 7 and 8 that redirects programs trying to write to system locations and instead redirects those accesses to a user directory.

To see a discussion on how this affects Git performance, read here:

To disable this driver, in regedit, change the "start" key at HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/luafv to 4 to disable the driver. Then, put UAC to its lowest setting, "never notify".

If the disabling of this driver makes you wary (it should), an alternative is running on a drive (or partition) different than your system partition. Apparently the driver only runs on file access on the system partition. I have a second hard drive and see identical results when run with this registry modification on my C drive as I do without it on the D drive.

This change takes time git status from 2.5 seconds down to 0.7 seconds.

You also might want to follow and to check out what additional work is underway for speed issues in Windows.

How to format dateTime in django template?

{{ wpis.entry.lastChangeDate|date:"SHORT_DATETIME_FORMAT" }}

Getting "unixtime" in Java

Java 8 added a new API for working with dates and times. With Java 8 you can use

import java.time.Instant
long unixTimestamp =; returns an Instant that represents the current system time. With getEpochSecond() you get the epoch seconds (unix time) from the Instant.

How can I select the record with the 2nd highest salary in database Oracle?

This query works in SQL*PLUS to find out the 2nd Highest Salary -


This is double sub-query.

I hope this helps you..

How to save username and password with Mercurial?

If you are using TortoiseHg you have to perform these three steps shown in the attached screen shot, this would add your credentials for the specific repository you are working with.

enter image description here

To add global settings you can access the file C:\users\\mercurial.ini and add the section

bb.username = $username
bb.password = $password

Hope this helps.

How to make a node.js application run permanently?

Although the other answers solve the OP's problem, they are all overkill and do not explain why he or she is experiencing this issue.

The key is this line, "I close putty, then I cannot reach the address"

When you are logged into your remote host on Putty you have started an SSH linux process and all commands typed from that SSH session will be executed as children of said process.

Your problem is that when you close Putty you are exiting the SSH session which kills that process and any active child processes. When you close putty you inadvertently kill your server because you ran it in the foreground. To avoid this behavior run the server in the background by appending & to your command:

node /srv/www/MyUserAccount/server/server.js &

The problem here is a lack of linux knowledge and not a question about node. For some more info check out:


As others have mentioned, the node server may still die when exiting the terminal. A common gotcha I have come across is that even though the node process is running in bg, it's stdout and stderr is still pointed at the terminal. This means that if the node server writes to console.log or console.error it will receive a broken pipe error and crash. This can be avoided by piping the output of your process:

node /srv/www/MyUserAccount/server/server.js > stdout.txt 2> stderr.txt &

If the problem persists then you should look into things like tmux or nohup, which are still more robust than node specific solutions, because they can be used to run all types of processes (databases, logging services, other languages).

A common mistake that could cause the server to exit is that after running the nohup node your_path/server.js & you simply close the Putty terminal by a simple click. You should use exit command instead, then your node server will be up and running.

How to check if a string contains text from an array of substrings in JavaScript?

You can check like this:

<!DOCTYPE html>
      <script src=""></script>
         var list = ["bad", "words", "include"] 
         var sentence = $("#comments_text").val()

         $.each(list, function( index, value ) {
           if (sentence.indexOf(value) > -1) {
      <input id="comments_text" value="This is a bad, with include test"> 

Parse date without timezone javascript

The date is parsed correctly, it's just toString that converts it to your local timezone:

let s = "2005-07-08T11:22:33+0000";_x000D_
let d = new Date(Date.parse(s));_x000D_
// this logs for me _x000D_
// "Fri Jul 08 2005 13:22:33 GMT+0200 (Central European Summer Time)" _x000D_
// and something else for you_x000D_
console.log(d.toString()) _x000D_
// this logs_x000D_
// Fri, 08 Jul 2005 11:22:33 GMT_x000D_
// for everyone_x000D_

Javascript Date object are timestamps - they merely contain a number of milliseconds since the epoch. There is no timezone info in a Date object. Which calendar date (day, minutes, seconds) this timestamp represents is a matter of the interpretation (one of to...String methods).

The above example shows that the date is being parsed correctly - that is, it actually contains an amount of milliseconds corresponding to "2005-07-08T11:22:33" in GMT.

How to iterate over associative arrays in Bash

You can access the keys with ${!array[@]}:

bash-4.0$ echo "${!array[@]}"
foo bar

Then, iterating over the key/value pairs is easy:

for i in "${!array[@]}"
  echo "key :" $i
  echo "value:" ${array[$i]}

Arrays.fill with multidimensional array in Java

Using Java 8, you can declare and initialize a two-dimensional array without using a (explicit) loop as follows:

int x = 20; // first dimension
int y = 4; // second dimension

double[][] a = IntStream.range(0, x)
                        .mapToObj(i -> new double[y])
                        .toArray(i -> new double[x][]);

This will initialize the arrays with default values (0.0 in the case of double).

In case you want to explicitly define the fill value to be used, You can add in a DoubleStream:

int x = 20; // first dimension
int y = 4; // second dimension
double v = 5.0; // fill value

double[][] a = IntStream
        .range(0, x)
        .mapToObj(i -> DoubleStream.generate(() -> v).limit(y).toArray())
        .toArray(i -> new double[x][]);

Check if number is decimal

Maybe try looking into this as well


Modify table: How to change 'Allow Nulls' attribute from not null to allow null

-- replace NVARCHAR(42) with the actual type of your column
ALTER TABLE your_table

How to delete the last row of data of a pandas dataframe

drop returns a new array so that is why it choked in the og post; I had a similar requirement to rename some column headers and deleted some rows due to an ill formed csv file converted to Dataframe, so after reading this post I used:

newList = pd.DataFrame(newList)
newList.columns = ['Area', 'Price']
# newList = newList.drop(0)
# newList = newList.drop(len(newList))
newList = newList[1:-1]

and it worked great, as you can see with the two commented out lines above I tried the drop.() method and it work but not as kool and readable as using [n:-n], hope that helps someone, thanks.

Trying Gradle build - "Task 'build' not found in root project"

You didn't do what you're being asked to do.

What is asked:

I have to execute ../gradlew build

What you do

cd ..
gradlew build

That's not the same thing.

The first one will use the gradlew command found in the .. directory (mdeinum...), and look for the build file to execute in the current directory, which is (for example) chapter1-bookstore.

The second one will execute the gradlew command found in the current directory (mdeinum...), and look for the build file to execute in the current directory, which is mdeinum....

So the build file executed is not the same.

Creating a ZIP archive in memory using System.IO.Compression

Just another version of zipping without writing any file.

string fileName = "export_" + DateTime.Now.ToString("yyyyMMddhhmmss") + ".xlsx";
byte[] fileBytes = here is your file in bytes
byte[] compressedBytes;
string fileNameZip = "Export_" + DateTime.Now.ToString("yyyyMMddhhmmss") + ".zip";

using (var outStream = new MemoryStream())
    using (var archive = new ZipArchive(outStream, ZipArchiveMode.Create, true))
        var fileInArchive = archive.CreateEntry(fileName, CompressionLevel.Optimal);
        using (var entryStream = fileInArchive.Open())
        using (var fileToCompressStream = new MemoryStream(fileBytes))
    compressedBytes = outStream.ToArray();

Converting any string into camel case

My ES6 approach:

const camelCase = str => {
  let string = str.toLowerCase().replace(/[^A-Za-z0-9]/g, ' ').split(' ')
                  .reduce((result, word) => result + capitalize(word.toLowerCase()))
  return string.charAt(0).toLowerCase() + string.slice(1)

const capitalize = str => str.charAt(0).toUpperCase() + str.toLowerCase().slice(1)

let baz = 'foo bar'
let camel = camelCase(baz)
console.log(camel)  // "fooBar"
camelCase('foo bar')  // "fooBar"
camelCase('FOO BAR')  // "fooBar"
camelCase('x nN foo bar')  // "xNnFooBar"
camelCase('!--foo-¿?-bar--121-**%')  // "fooBar121"

What is the difference between Google App Engine and Google Compute Engine?

Google Compute Engine (GCE)

Virtual Machines (VMs) hosted in the cloud. Before the cloud, these were often called Virtual Private Servers (VPS). You'd use these the same way you'd use a physical server, where you install and configure the operating system, install your application, install the database, keep the OS up-to-date, etc. This is known as Infrastructure-as-a-Service (IaaS).

VMs are most useful when you have an existing application running on a VM or server in your datacenter, and want to easily migrate it to GCP.

Google App Engine

App Engine hosts and runs your code, without requiring you to deal with the operating system, networking, and many of the other things you'd have to manage with a physical server or VM. Think of it as a runtime, which can automatically deploy, version, and scale your application. This is called Platform-as-a-Service (PaaS).

App Engine is most useful when you want automated deployment and automated scaling of your application. Unless your application requires custom OS configuration, App Engine is often advantageous over configuring and managing VMs by hand.

Why do I need to override the equals and hashCode methods in Java?

It is useful when using Value Objects. The following is an excerpt from the Portland Pattern Repository:

Examples of value objects are things like numbers, dates, monies and strings. Usually, they are small objects which are used quite widely. Their identity is based on their state rather than on their object identity. This way, you can have multiple copies of the same conceptual value object.

So I can have multiple copies of an object that represents the date 16 Jan 1998. Any of these copies will be equal to each other. For a small object such as this, it is often easier to create new ones and move them around rather than rely on a single object to represent the date.

A value object should always override .equals() in Java (or = in Smalltalk). (Remember to override .hashCode() as well.)

Convert XML to JSON (and back) using Javascript

You can also use txml. It can parse into a DOM made of simple objects and stringify. In the result, the content will be trimmed. So formating of the original with whitespaces will be lost. But this could be used very good to minify HTML.

const xml = require('txml');
const data = `
<tag>tag content</tag>
<tag2>another content</tag2>
  <insideTag>inside content</insideTag>
  <emptyTag />

const dom = xml(data); // the dom can be JSON.stringified

xml.stringify(dom); // this will return the dom into an xml-string

Disclaimer: I am the author of txml, the fastest xml parser in javascript.

nginx: connect() failed (111: Connection refused) while connecting to upstream

I don't think that solution would work anyways because you will see some error message in your error log file.

The solution was a lot easier than what I thought.

simply, open the following path to your php5-fpm

sudo nano /etc/php5/fpm/pool.d/www.conf

or if you're the admin 'root'

nano /etc/php5/fpm/pool.d/www.conf

Then find this line and uncomment it:

listen.allowed_clients =

This solution will make you be able to use listen = in your vhost blocks

like this: fastcgi_pass;

after you make the modifications, all you need is to restart or reload both Nginx and Php5-fpm


sudo service php5-fpm restart


sudo service php5-fpm reload


sudo service nginx restart


sudo service nginx reload

From the comments:

Also comment

;listen = /var/run/php5-fpm.sock 

and add

listen = 9000

Cycles in family tree software

Duplicate the father (or use symlink/reference).

For example, if you are using hierarchical database:

$ #each person node has two nodes representing its parents.
$ mkdir Family
$ mkdir Family/Son
$ mkdir Family/Son/Daughter
$ mkdir Family/Son/Father
$ mkdir Family/Son/Daughter/Father
$ ln -s Family/Son/Daughter/Father Family/Son/Father
$ mkdir Family/Son/Daughter/Wife
$ tree Family
+-- Son
    +-- Daughter
    ¦   +-- Father
    ¦   +-- Wife
    +-- Father -> Family/Son/Daughter/Father

4 directories, 1 file

OpenCV C++/Obj-C: Detecting a sheet of paper / Square Detection

Once you have detected the bounding box of the document, you can perform a four-point perspective transform to obtain a top-down birds eye view of the image. This will fix the skew and isolate only the desired object.

Input image:

Detected text object

Top-down view of text document


from imutils.perspective import four_point_transform
import cv2
import numpy

# Load image, grayscale, Gaussian blur, Otsu's threshold
image = cv2.imread("1.png")
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray, (7,7), 0)
thresh = cv2.threshold(blur, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)[1]

# Find contours and sort for largest contour
cnts = cv2.findContours(thresh, cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)
cnts = cnts[0] if len(cnts) == 2 else cnts[1]
cnts = sorted(cnts, key=cv2.contourArea, reverse=True)
displayCnt = None

for c in cnts:
    # Perform contour approximation
    peri = cv2.arcLength(c, True)
    approx = cv2.approxPolyDP(c, 0.02 * peri, True)
    if len(approx) == 4:
        displayCnt = approx

# Obtain birds' eye view of image
warped = four_point_transform(image, displayCnt.reshape(4, 2))

cv2.imshow("thresh", thresh)
cv2.imshow("warped", warped)
cv2.imshow("image", image)

How do I check/uncheck all checkboxes with a button using jQuery?

You can try this


Class .checkAll is a checkbox which controls the bulk action

How can I get Docker Linux container information from within the container itself?

Docker sets the hostname to the container ID by default, but users can override this with --hostname. Instead, inspect /proc:

$ more /proc/self/cgroup

Here's a handy one-liner to extract the container ID:

$ grep "memory:/" < /proc/self/cgroup | sed 's|.*/||'

Cannot invoke an expression whose type lacks a call signature

Perhaps create a shared Fruit interface that provides isDecayed. fruits is now of type Fruit[] so the type can be explicit. Like this:

interface Fruit {
    isDecayed: boolean;

interface Apple extends Fruit {
    color: string;

interface Pear extends Fruit {
    weight: number;

interface FruitBasket {
    apples: Apple[];
    pears: Pear[];

const fruitBasket: FruitBasket = { apples: [], pears: [] };
const key: keyof FruitBasket = Math.random() > 0.5 ? 'apples': 'pears'; 
const fruits: Fruit[] = fruitBasket[key];

const freshFruits = fruits.filter((fruit) => !fruit.isDecayed);

What does 'URI has an authority component' mean?

An authority is a portion of a URI. Your error suggests that it was not expecting one. The authority section is shown below, it is what is known as the website part of the url.

From RFC3986 on URIs:

The following is an example URI and its component parts:

     \_/   \______________/\_________/ \_________/ \__/
      |           |            |            |        |
   scheme     authority       path        query   fragment
      |   _____________________|__
     / \ /                        \

So there are two formats, one with an authority and one not. Regarding slashes:

"When authority is not present, the path cannot begin with two slash
characters ("//")."

Source: (search for text 'authority is not present, the path cannot begin with two slash')

Replace None with NaN in pandas dataframe

The following line replaces None with NaN:

df['column'].replace('None', np.nan, inplace=True)

Make one div visible and another invisible

I don't think that you really want an iframe, do you?

Unless you're doing something weird, you should be getting your results back as JSON or (in the worst case) XML, right?

For your white box / extra space issue, try

style="display: none;"

instead of

style="visibility: hidden;"

How to copy and paste worksheets between Excel workbooks?

I am just going to post the answer for python so people will have a reference.

from win32com.client import Dispatch
from win32com.client import constants
import win32com.client

xlApp = Dispatch("Excel.Application")
xlWb = xlApp.Workbooks.Open(filename_xls)
ws = xlWb.Worksheets(1)
xlWbTemplate = xlApp.Workbooks.Open('otherfile.xls')
ws_sub = xlWbTemplate.Worksheets(1)
ws_sub = xlWbTemplate.Worksheets(2)


Do I need to convert .CER to .CRT for Apache SSL certificates? If so, how?

According to documentation mod_ssl:

   Name: SSLCertificateFile
   Description: Server PEM-encoded X.509 certificate file

Certificate file should be PEM-encoded X.509 Certificate file:

openssl x509 -inform DER -in certificate.cer -out certificate.pem

HTML -- two tables side by side

With CSS: table {float:left;}? ?

Pass variables by reference in JavaScript

Yet another approach to pass any (local, primitive) variables by reference is by wrapping variable with closure "on the fly" by eval. This also works with "use strict". (Note: be aware that eval is not friendly to JavaScript optimizers, and also missing quotes around variable name may cause unpredictive results)

"use strict"

// Return text that will reference variable by name (by capturing that variable to closure)
function byRef(varName){
    return "({get value(){return "+varName+";}, set value(v){"+varName+"=v;}})";

// Demo

// Assign argument by reference
function modifyArgument(argRef, multiplier){
    argRef.value = argRef.value * multiplier;

    var x = 10;

    alert("x before: " + x);
    modifyArgument(eval(byRef("x")), 42);
    alert("x after: " + x);

Live sample: Button OnClick event not firing

Try to go into Design mode in Visual Studio, locate the button and double click the button that should setup the event. Otherwise once the button is selected in Design more, go to the properties and try setting it from there.

warning: assignment makes integer from pointer without a cast

The expression *src refers to the first character in the string, not the whole string. To reassign src to point to a different string tgt, use src = tgt;.

Better way to get type of a Javascript variable?

You may find the following function useful:

function typeOf(obj) {
  return {}' ')[1].slice(0, -1).toLowerCase();

Or in ES7 (comment if further improvements)

const { toString } = Object.prototype;

function typeOf(obj) {
  const stringified = obj::toString();
  const type = stringified.split(' ')[1].slice(0, -1);
  return type.toLowerCase();


typeOf(); //undefined
typeOf(null); //null
typeOf(NaN); //number
typeOf(5); //number
typeOf({}); //object
typeOf([]); //array
typeOf(''); //string
typeOf(function () {}); //function
typeOf(/a/) //regexp
typeOf(new Date()) //date
typeOf(new Error) //error
typeOf(Promise.resolve()) //promise
typeOf(function *() {}) //generatorfunction
typeOf(new WeakMap()) //weakmap
typeOf(new Map()) //map
typeOf(async function() {}) //asyncfunction

Thanks @johnrees for notifying me of: error, promise, generatorfunction

JSON formatter in C#?

Here's a compact version of a JSON beautifier.

private const string INDENT_STRING = "    ";

static string FormatJson(string json) {

    int indentation = 0;
    int quoteCount = 0;
    var result = 
        from ch in json
        let quotes = ch == '"' ? quoteCount++ : quoteCount
        let lineBreak = ch == ',' && quotes % 2 == 0 ? ch + Environment.NewLine +  String.Concat(Enumerable.Repeat(INDENT_STRING, indentation)) : null
        let openChar = ch == '{' || ch == '[' ? ch + Environment.NewLine + String.Concat(Enumerable.Repeat(INDENT_STRING, ++indentation)) : ch.ToString()
        let closeChar = ch == '}' || ch == ']' ? Environment.NewLine + String.Concat(Enumerable.Repeat(INDENT_STRING, --indentation)) + ch : ch.ToString()
        select lineBreak == null    
                    ? openChar.Length > 1 
                        ? openChar 
                        : closeChar
                    : lineBreak;

    return String.Concat(result);


             "formatted_address":"New York, NY, USA",
                    "long_name":"New York",
                     "short_name":"New York",
                    "long_name":"New York",
                     "short_name":"New York",
                    "long_name":"New York",
                    "long_name":"United States",

Visual Studio 2017 - Could not load file or assembly 'System.Runtime, Version=' or one of its dependencies

I had the same problem and no suggested solutions that I found worked. My solution for this issue was: Check App.config and packages.config to see if the versions match.

Originally my app.config contained:

  <assemblyIdentity name="System.Runtime" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
  <bindingRedirect oldVersion="" newVersion="" />

But the packages.config contained:

<package id="System.Runtime" version="4.3.0" targetFramework="net461" requireReinstallation="true" />

I modified the app.config entry to match packages.config for the newVersion:

  <assemblyIdentity name="System.Runtime" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
  <bindingRedirect oldVersion="" newVersion="4.3.0" />

After the change, the issue was resolved.

How to use the addr2line command in Linux?

Try adding the -f option to show the function names :

addr2line -f -e a.out 0x4005BDC

variable or field declared void

It for example happens in this case here:

void initializeJSP(unknownType Experiment);

Try using std::string instead of just string (and include the <string> header). C++ Standard library classes are within the namespace std::.

How do I make case-insensitive queries on Mongodb?

To find case Insensitive string use this,

var thename = "Andrew";

Where do I find old versions of Android NDK?

I successfully opened gstreamer SDK tutorials in Eclipse.

All I needed is to use an older version of ndk. specificly 9d.

(10c and 10d does not work, 10b - works just for tutorial-1 )

9d does work for all tutorials ! and you can:

  1. Download it from:

  2. Extract it.

  3. set it in eclipse->window->preferences->Android->NDK->NDK location.

  4. build - (ctrl+b).

How do you clear a stringstream variable?

I am always scoping it:

    std::stringstream ss;
    ss << "what";

    std::stringstream ss;
    ss << "the";

    std::stringstream ss;
    ss << "heck";

jQuery: load txt file and insert into div

The .load("file.txt") is much easier. Which works but even if testing, you won't get results from a localdrive, you'll need an actual http server. The invisible error is an XMLHttpRequest error.

Create JSON object dynamically via JavaScript (Without concate strings)

Perhaps this information will help you.

var sitePersonel = {};_x000D_
var employees = []_x000D_
sitePersonel.employees = employees;_x000D_
var firstName = "John";_x000D_
var lastName = "Smith";_x000D_
var employee = {_x000D_
  "firstName": firstName,_x000D_
  "lastName": lastName_x000D_
var manager = "Jane Doe";_x000D_
sitePersonel.employees[0].manager = manager;_x000D_

Angularjs dynamic ng-pattern validation

This is an interesting problem, complex Angular validation. The following fiddle implements what you want:


I created a new directive, rpattern, that is a mix of Angular's ng-required and the ng-pattern code from input[type=text]. What it does is watch the required attribute of the field and take that into account when validating with regexp, i.e. if not required mark field as valid-pattern.


  • Most of the code is from Angular, tailored to the needs of this.
  • When the checkbox is checked, the field is required.
  • The field is not hidden when the required checkbox is false.
  • The regular expression is simplified for the demo (valid is 3 digits).

A dirty (but smaller) solution, if you do not want a new directive, would be something like:

$scope.phoneNumberPattern = (function() {
    var regexp = /^\(?(\d{3})\)?[ .-]?(\d{3})[ .-]?(\d{4})$/;
    return {
        test: function(value) {
            if( $scope.requireTel === false ) {
                return true;
            return regexp.test(value);

And in HTML no changes would be required:

<input type="text" ng-model="..." ng-required="requireTel"
    ng-pattern="phoneNumberPattern" />

This actually tricks angular into calling our test() method, instead of RegExp.test(), that takes the required into account.

Retrieving the first digit of a number

Almost certainly more efficient than using Strings:

int firstDigit(int x) {
    while (x > 9) {
        x /= 10;
    return x;

(Works only for nonnegative integers.)

Make the first character Uppercase in CSS

Make it lowercase first:

.m_title {text-transform: lowercase}

Then make it the first letter uppercase:

.m_title:first-letter {text-transform: uppercase}

"text-transform: capitalize" works for a word; but if you want to use for sentences this solution is perfect.

Access to ES6 array element index inside for-of loop

Use Array.prototype.keys:

for (const index of [1, 2, 3, 4, 5].keys()) {_x000D_

If you want to access both the key and the value, you can use Array.prototype.entries() with destructuring:

for (const [index, value] of [1, 2, 3, 4, 5].entries()) {_x000D_
  console.log(index, value);_x000D_

Excel VBA function to print an array to the workbook

Create a variant array (easiest by reading equivalent range in to a variant variable).

Then fill the array, and assign the array directly to the range.

Dim myArray As Variant

myArray = Range("blahblah")

Range("bingbing") = myArray

The variant array will end up as a 2-D matrix.

Cannot overwrite model once compiled Mongoose

just export like this exports.User = mongoose.models.User || mongoose.model('User', userSchema);

How do I remove carriage returns with Ruby?

I think your regex is almost complete - here's what I would do:

lines2 = lines.gsub(/[\r\n]+/m, "\n")

In the above, I've put \r and \n into a class (that way it doesn't matter in which order they might appear) and added the "+" qualifier (so that "\r\n\r\n\r\n" would also match once, and the whole thing replaced with "\n")

How to add RSA key to authorized_keys file?

Make sure when executing Michael Krelin's solution you do the following

cat <your_public_key_file> >> ~/.ssh/authorized_keys

Note the double > without the double > the existing contents of authorized_keys will be over-written (nuked!) and that may not be desirable

How to properly validate input values with React.JS?

First, here is an example of what I'll mention below:

How to properly validate input values with React.JS?

However you want. React is for rendering a data model. The data model should know what is valid or not. You can use Backbone models, JSON data, or anything you want to represent the data and it's error state.

More specifically:

React is generally agnostic towards your data. It's for rendering and dealing with events.

The rules to follow are:

  1. elements can change their state.
  2. they cannot change props.
  3. they can invoke a callback that will change top level props.

How to decide if something should be a prop or a state? Consider this: would ANY part of your app other than the text field want to know that the value entered is bad? If no, make it a state. If yes, it should be a prop.

For example, if you wanted a separate view to render "You have 2 errors on this page." then your error would have to be known to a toplevel data model.

Where should that error live?
If your app was rendering Backbone models (for example), the model itself would have a validate() method and validateError property you could use. You could render other smart objects that could do the same. React also says try to keep props to a minimum and generate the rest of the data. so if you had a validator (e.g. then your validations could trickle down and any component could check props with it's matching validation to see if it's valid.

It's largely up to you.

(I am personally using Backbone models and rendering them in React. I have a toplevel error alert that I show if there is an error anywhere, describing the error.)

How to implement reCaptcha for ASP.NET MVC?

An async version for MVC 5 (i.e. avoiding ActionFilterAttribute, which is not async until MVC 6) and reCAPTCHA 2


public class HomeController : Controller
    public async Task<ActionResult> ContactSubmit(
        [Bind(Include = "FromName, FromEmail, FromPhone, Message, ContactId")]
        ContactViewModel model)
        if (!await RecaptchaServices.Validate(Request))
            ModelState.AddModelError(string.Empty, "You have not confirmed that you are not a robot");
        if (ModelState.IsValid)


@model MyMvcApp.Models.ContactViewModel

@*This is assuming the master layout places the styles section within the head tags*@
@section Styles {
    <script src=''></script>

@using (Html.BeginForm("ContactSubmit", "Home",FormMethod.Post, new { id = "contact-form" }))
    <div class="form-group">
      @Html.LabelFor(m => m.Message) 
      @Html.TextAreaFor(m => m.Message, new { @class = "form-control", @cols = "40", @rows = "3" })
      @Html.ValidationMessageFor(m => m.Message)

    <div class="row">
      <div class="g-recaptcha" data-sitekey='@System.Configuration.ConfigurationManager.AppSettings["RecaptchaClientKey"]'></div>

    <div class="row">
      <input type="submit" id="submit-button" class="btn btn-default" value="Send Your Message" />


using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using System.Web;
using System.Configuration;
using System.Net.Http;
using System.Net.Http.Headers;
using Newtonsoft.Json;
using System.Runtime.Serialization;

namespace MyMvcApp.Services
    public class RecaptchaServices
        //ActionFilterAttribute has no async for MVC 5 therefore not using as an actionfilter attribute - needs revisiting in MVC 6
        internal static async Task<bool> Validate(HttpRequestBase request)
            string recaptchaResponse = request.Form["g-recaptcha-response"];
            if (string.IsNullOrEmpty(recaptchaResponse))
                return false;
            using (var client = new HttpClient { BaseAddress = new Uri("") })
                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                var content = new FormUrlEncodedContent(new[]
                    new KeyValuePair<string, string>("secret", ConfigurationManager.AppSettings["RecaptchaSecret"]),
                    new KeyValuePair<string, string>("response", recaptchaResponse),
                    new KeyValuePair<string, string>("remoteip", request.UserHostAddress)
                var result = await client.PostAsync("/recaptcha/api/siteverify", content);
                string jsonString = await result.Content.ReadAsStringAsync();
                var response = JsonConvert.DeserializeObject<RecaptchaResponse>(jsonString);
                return response.Success;

        internal class RecaptchaResponse
            [DataMember(Name = "success")]
            public bool Success { get; set; }
            [DataMember(Name = "challenge_ts")]
            public DateTime ChallengeTimeStamp { get; set; }
            [DataMember(Name = "hostname")]
            public string Hostname { get; set; }
            [DataMember(Name = "error-codes")]
            public IEnumerable<string> ErrorCodes { get; set; }



    <add key="RecaptchaSecret" value="***secret key from***" />
    <add key="RecaptchaClientKey" value="***client key from***" />

How can I get all a form's values that would be submitted without submitting

You can use this simple loop to get all the element names and their values.

var params = '';
for( var i=0; i<document.FormName.elements.length; i++ )
   var fieldName = document.FormName.elements[i].name;
   var fieldValue = document.FormName.elements[i].value;

   // use the fields, put them in a array, etc.

   // or, add them to a key-value pair strings, 
   // as in regular POST

   params += fieldName + '=' + fieldValue + '&';

// send the 'params' variable to web service, GET request, ...

How to print to console when using Qt

If you are printing to stderr using the stdio library, a call to fflush(stderr) should flush the buffer and get you real-time logging.

How to download python from command-line?

wget --no-check-certificate
tar -xzf Python-2.7.11.tgz  
cd Python-2.7.11

Now read the README file to figure out how to install, or do the following with no guarantees from me that it will be exactly what you need.

sudo make install  

For Python 3.5 use the following download address:

For other versions and the most up to date download links: