Anil's Technical Blog

MacOSX Sed: extra characters at the end of

2016-01-06T15:05:00.001-08:00

if your sed is throwing something like extra characters at the end of p command

then do

sed -i '' 'regex' filename

Remember to add the '' before regex.

Tip: Elasticsearch OSX ConnectException

2015-08-19T13:36:00.002-07:00

If you downloaded the latest Elasticsearch installation and you are getting the following exception:

org.elasticsearch.common.netty.channel.ConnectTimeoutException: connection timed out:/xyz.def.zzzz:9300
at org.elasticsearch.common.netty.channel.socket.nio.NioClientBoss.processConnectTimeout(NioClientBoss.java:139)
at org.elasticsearch.common.netty.channel.socket.nio.NioClientBoss.process(NioClientBoss.java:83)
at org.elasticsearch.common.netty.channel.socket.nio.AbstractNioSelector.run(AbstractNioSelector.java:337)
at org.elasticsearch.common.netty.channel.socket.nio.NioClientBoss.run(NioClientBoss.java:42)
at org.elasticsearch.common.netty.util.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:108)
at org.elasticsearch.common.netty.util.internal.DeadLockProofWorker$1.run(DeadLockProofWorker.java:42)

Solution

go to config/elasticsearch.yml

Uncomment the following line
discovery.zen.ping.multicast.enabled: false

Restart Elasticsearch

Git Tip: Repository not found

2015-07-14T15:51:00.001-07:00

If you get any of the following errors:
GitLab: The project you were looking for could not be found.
Git The Repository not found
Please make sure you have the correct access rights

and the repository exists.

when you do operations such as git clone or git push,
it is possible that your ssh key has not been added with ssh-agent

$ ssh-add
Enter passphrase for /home/name/.ssh/id_rsa: [] Identity added: /home/name/.ssh/id_rsa

After this, it should hopefully work

JSONP: Escape JSON String

2014-09-16T22:55:00.003-07:00

Assume you have a JSON string that you are going to send as result value back to Javascript, then you need to do the following:

String dataString = stringWriter.toString();
dataString = dataString.replaceAll("\\u2028","\\\\u2028");
dataString = dataString.replaceAll("\\u2029","\\\\u2029");

Basically, you need to escape the unicode characters.

Tip: Apache Kafka

2014-07-21T14:06:00.002-07:00

If you get the following exception:
$ ./zookeeper-server-start.sh ../config/zookeeper.properties
Error: Could not find or load main class org.apache.zookeeper.server.quorum.QuorumPeerMain

then you will have to do the following:
$ ./gradlew jar

to build the Kafka distribution and get the dependencies.

Tip: Linux Determine File Sizes in your home directory

2014-05-02T12:31:00.003-07:00

anil@localhost:~$ du -sh * > largefiles

You can then look inside the file largefiles.

Tip: IntelliJ IDEA : Do not want unlimited whitespace at the end of each line

2014-04-30T21:02:00.002-07:00

File menu -> Settings -> Editor -> Virtual Space and uncheck 'Allow placement of caret after end of line'.

Also uncheck the other options in the Virtual Space panel.

If you want to remove trailing whitespaces, you can do
File menu-->Settings --> Editor --> Strip Whitespaces on Save to either "All" or "ModifiedLines".

Clean Up Root Partition on Fedora

2014-01-07T08:42:00.000-08:00

If you have the following problems:

Root partition / is using 100% of allocated disk space
Root partition / is close to using 100% of allocated disk space

Then,

$> sudo yum install bleachbit
$> su - -c "bleachbit"

Use bleachbit to clean up unwanted files.

Copy Video on iPhone without iTunes

2013-12-24T19:15:00.000-08:00

If you are in need of copying a home video on to your iPhone and you have lost the computer which has the original iTunes sync, do not despair.

VLC app on ios is there for the rescue.

Official Documentation: https://wiki.videolan.org/Documentation:IOS

Steps

Temporarily turn off the lock feature of your iPhone. You can bring it back after the video upload.
Download VLC player from the App Store. Ensure that the vendor is VideoLan.
Ensure your iphone and computer are connected to the same WIFI.
Open VLC app.
On the top left hand corner, is the hat symbol. Click on hat.
Go to Wiki Upload. Enable the server. Note down the IP address it provides.
Go to your browser and type in the IP address: something starting with http:
You will see Fig 1
Click upload files button and choose the video file.
Once the file is uploaded, enjoy the home video. Remember VLC can play many formats : mp3, mp4, m4u etc.
Remember to turn back the locking feature on your iphone.
Fig1: Browser Interface

Tips for FitBit

2013-10-16T12:18:00.005-07:00

Picked up from http://www.sparkpeople.com/mypage_public_journal_individual.asp?blog_id=2471667

Reset your FitBit:

Dock it, turn the dock over, and hit the button underneath with a pen or paperclip. The FitBit will reboot, displaying the current firmware version and the battery level, then will continue charging. This will not delete any of the tracker data.

Completely erase all information on your FitBit:

1. Put the fitbit on the base station
2. Look under base station and you'll see a tiny hole. That's the reset button that you can push with a small pen or paperclip.
3. Press and hold the button on the Fitbit itself and press the reset button
4. Keep the button on the Fitbit pressed for 6 seconds.
5. Take the Fitbit off the base station
6. Press the button on the Fitbit
7. It should say "Testing" and then "Pass"
8. Press and hold the button until it says "Erase"

Power Off Your FitBit:

Unplug the dock. Dock the FitBit on the unplugged dock, then press the reset button on the bottom.

Tip: Mac OSX: Start IntelliJ with sudo permissions

2013-08-30T20:07:00.001-07:00

There may be instances where the code you are developing is binding to a particular port that is lower than 1024. So you will not be able to bind to that port.

You will see something like a SocketException : permission denied.

If you are sure that this is temporary and you are developing on your Apple laptop, then do the following in a terminal window:

$>cd IntelliJ\ IDEA\ 12\ CE.app/Contents/MacOS/

$> sudo ./idea

Now IntelliJ is running with sudo permissions.

WARNING: This is a sensitive operation. Do not try it on Apple based servers or production environments.

Netty: UDP based Server Example

2013-08-30T20:02:00.002-07:00

An example is the Quote of the Moment Server.

Package is:
https://github.com/netty/netty/blob/master/example/src/main/java/io/netty/example/qotm/

Server is:
https://github.com/netty/netty/blob/master/example/src/main/java/io/netty/example/qotm/QuoteOfTheMomentServer.java

Server Handler is:
https://github.com/netty/netty/blob/master/example/src/main/java/io/netty/example/qotm/QuoteOfTheMomentServerHandler.java

Tip: Hibernate PersistenceException :

2013-02-07T11:21:00.001-08:00

If you are seeing the following error "No Persistence provider for EntityManager named" and scratching your brains, ensure that the hibernate-entitymanager.jar is on the classpath.

Also you should have a META-INF/persistence.xml in your jars someplace.

Tip: Eclipse:: getTextContent() is undefined for Node/Element

2013-02-04T08:24:00.003-08:00

In Eclipse, if you see the an error saying getTextContent() is undefined for Node/Element, then follow:
http://mergetag.com/the-method-gettextcontent-is-undefined-for-the-type-node/

Mockito return the value from the response

2012-09-11T12:56:00.002-07:00

An example:
private HttpServletRequest request = mock(HttpServletRequest.class);
    private HttpServletResponse response = mock(HttpServletResponse.class);

    @Test
    public void testAuthz() throws Exception {
        AuthorizationEndpoint endpoint = new AuthorizationEndpoint();
        when(request.getParameter("response_type")).thenReturn(ResponseType.CODE.toString());
        when(request.getParameter("client_id")).thenReturn("test_id");
        when(request.getParameter("redirect_uri")).thenReturn("http://localhost");

        final ArrayList values = new ArrayList();
        doAnswer(new Answer() {
            @Override
            public Object answer(InvocationOnMock invocation) throws Throwable {
                String temp = (String) invocation.getArguments()[0];
                values.add(temp);
                return null;
            }
        }).when(response).sendRedirect(anyString());

        httpRequest("GET", "/authorization");

        endpoint.service(request, response);

        String redirectURL = values.get(0);

        URL url = new URL(redirectURL);
        String fragment = url.toURI().getQuery();
        Map map = OAuthUtils.decodeForm(fragment);

        assertNotNull(map.get(OAuth.OAUTH_CODE));
    }

    private void httpRequest(String method, String pathInfo) {
        when(request.getMethod()).thenReturn(method);
        when(request.getPathInfo()).thenReturn(pathInfo);
    }

Fedora: Skype Issue: libXv.so.1: cannot open

2012-09-10T09:51:00.000-07:00

If you try to run skype and get the following error
skype: error while loading shared libraries: libXv.so.1: cannot open

$>sudo yum install alsa-lib.i686 libXv.i686 libXScrnSaver.i686 qt.i686 qt-x11.i686

Eclipse Heap Settings on Mac

2012-09-05T07:03:00.000-07:00

Locating the eclipse.ini is tricky on a mac.

To locate it, right-click on the Eclipse Application icon and select "Show Package Contents", then double-click on the "Contents" folder and then double-click on the "MacOS" folder, the home of eclipse.ini.

You can use Applications->Text Edit to change the eclipse.ini file. :)

Usually you want to adjust the heap settings.

Fedora: yum-complete-transaction taking forever?

2012-08-29T22:37:00.003-07:00

It is possible that it may be in an infinite loop or such. Cleanup your yum transaction as follows:

yum install yum-utils
yum clean all
/usr/sbin/yum-complete-transaction --cleanup-only

Fedora: Remove old kernels

2012-08-15T08:30:00.000-07:00

Update your system
$ sudo yum -y update --skip-broken

Now remove old kernels
$ sudo package-cleanup --oldkernels -y

Android Tip: android.view.WindowManager$BadTokenException

2012-03-26T21:40:00.002-07:00

If you are using an ActivityGroup to display a series of activities, then you may encounter the infamous BadTokenException.

The location where you are getting the exception, will have a "this" usage for the context.

To get over this error, use "this.getParent()".

Eg: final ProgressDialog pbarDialog = new ProgressDialog( this.getParent() );

Android Tip: Dealing with Droid Spinner Background

2012-03-26T20:05:00.002-07:00

Droid seems to have an issue where in the spinner background is white and none of the elements are displayed even though they are available in the spinner.

This error has a workaround at http://stackoverflow.com/questions/4361604/how-to-change-the-spinner-font-color

GitHub: Dealing with Multiple Accounts and SSH Keys

2012-03-16T18:12:00.002-07:00

http://net.tutsplus.com/tutorials/tools-and-tips/how-to-work-with-github-and-multiple-accounts/

TIP: Fedora: No packages marked for update

2012-03-02T07:47:00.002-08:00

Causes:
1) Your fedora distribution may have been EOL. No more packages are available. You need to upgrade your version. OR
2) Your yum cache is out of date and needs a refresh.

$ sudo yum clean expire-cache
$ sudo yum update

TIP:Lenovo Thinkpad W520 Fedora 16 Internal Mic Not Working

2012-02-09T15:42:00.000-08:00

Solution as mentioned in
https://bugzilla.redhat.com/show_bug.cgi?id=752610 is

$ sudo vi /etc/modprobe.d/dist-alsa.conf

Add as the first line.
options snd-hda-intel index=0 model=thinkpad

Then reboot and you should be good to go.

If you are keen on seeing what my file looks like:

# ALSA Sound Support
#
# We want to ensure that snd-seq is always loaded for those who want to use
# the sequencer interface, but we can't do this automatically through udev # at the moment...so we have this rule (just for the moment).
#
# Remove the following line if you don't want the sequencer.

options snd-hda-intel index=0 model=thinkpad

install snd-pcm /sbin/modprobe --ignore-install snd-pcm && /sbin/modprobe snd-seq

TIP: Passphraseless SSH on Fedora

2012-01-25T20:42:00.001-08:00

If you are trying to set up passphraseless SSH on Fedora, then remember that the permissions on the file authorized_keys should be 644 ====================================================== .ssh$ chmod 644 authorized_keys anil@sadbhav:~/.ssh$ ssh localhost Last login: Sun Jan 22 21:42:06 2012 from localhost anil@sadbhav:~$ exit logout Connection to localhost closed. anil@sadbhav:~/.ssh$ chmod 644 known_hosts ================