Snippets

Linux
SQL
Java
Scala
1. SBT - Eclipse Plugin
Apache Webserver
1. Deny all methods excepting POST and GET
2. Rewrite all aliases for a domain to a single domain
Maven
Javascript / jQuery
Cascading Stylesheets / CSS
1. Calculations
Firefox
1. Configure address bar to return search results
Eclipse
1. Favorites
2. Template to insert a static logger instance
Atlassian
Git
1. Show changes in a dedicated date range
2. Git setup a server using the git protocol
Misc
1. Data Normalizing
XML / XSLT / XPath / Schema
1. XSLT Strip Namespaces for Output

A collection of snippets I’m using often but sometimes my brain refuses to remember ..

Linux

Create *nix timestamp

date --utc --date "2011-11-11 11:11:11" +%s

Convert screencast video

mencoder -idx input.ogv -ovc lavc -oac mp3lame -o output

monitor udev events from usb port etc..

udevadm monitor

bash/zsh use cursor up/down keys for command history up/down

bindkey "^[[A" history-search-backward
bindkey "^[[B" history-search-forward

TrueCrypt GUIless/console mount encrypted volume

sudo truecrypt -t -k "" --protect-hidden=no /path/to/encfile /path/to/mountpoint

Enable MTP Support

sudo apt-get install mtp-tools mtpfs

-> connect the device and detect vendor- and product-id

mtp-detect | grep idVendor
mtp-detect | grep idProduct

Add to /etc/udev/rules.d/55-android.rules:

SUBSYSTEM=="usb", ATTR{idVendor}=="VENDORID", ATTR{idProduct}=="PRODUCTID", MODE="0666"

sudo service udev restart

Connect:

mtpfs -o allow_other /media/GalaxyNexus

Disconnect:

fusermount -u /media/GalaxyNexus

Convert all mp3′s in a directory to aac

for f in *.mp3; do ffmpeg -i "$f" -acodec aac -strict experimental -ab 128k "${f%.mp3}.aac"; done

Find out which application runs on a given port and protocol

sudo fuser -n tcp 8080

List your hardware

sudo lshw

Directory tree comparison

diff -r dir1 dir2

Recording audio from the command line to a mp3

arecord -f cd -t raw | lame -x -r – outfile.mp3

List files and dirs by size

du -cks * |sort -gr

Backup directory using rsync with progress bar

rsync -h --progress --stats -r -tgo -l -p -D --update --delete-after /path/to/dir-to-be-saved /path/to/targetdir/

Debian/Ubuntu save a list of all installed packages and how to reinstall using this list

dpkg --get-selections > installed-packages
 
dpkg --set-selections < installed-packages
 
dselect

Benchmarking the Network Speed between to Workstations

sudo apt-get install iperf

On the target workstation start iperf in server mode:

iperf -s

On the other workstation start the benchmark

iperf -c SERVER_IP_ADDRESS

Tell SVN not to store your password in .svn ..

svn command --no-auth-cache

Execute function on shell script exit

#!/bin/sh
# exit function
onExit() {
   # do something here .. cleanup etc ....
}
# bind exit function
trap onExit ERR EXIT
 
# here's the normal code to be executed

Curl send header

curl -H "headername:value" url
 
e.g. curl -H "REMOTE_USER:foo" http://developers.android.com

Curl send POST request

curl -X POST url
 
e.g. curl -X POST http://developers.android.com

Curl get all response headers

curl -i url
 
e.g. curl -i http://developers.android.com

Run Apache Benchmark Tool (10 Requests, 5 Concurrent)

ab -n 10 -c 5 http://site.com

Screen detach session/ list / reattach

Detach: Ctrl + A + D

List:

$ screen -ls
There is a screen on:
    2859.pts-0.host    (11/07/11 20:18:00)    (Detached)
1 Socket in /var/run/screen/S-user.

Reattach:

screen -r 2859.pts-0.host

Join multiple videos into a single one

mencoder -oac copy -ovc copy -o outfile infile1 infile2 ... infileN
 
# or if ls -l filename* matches the correct order ..
 
mencoder -oac copy -ovc copy -o outfile filename*

Mount SSH filesystem with user mapping and symlinks

sudo sshfs user@host.com:/path/to/directory /path/to/local-directory -o uid=1000,allow_other,follow_symlinks,transform_symlinks,workaround=rename

netcat emulate http server

sudo nc -l 80

Emulate a http server using python

python -m SimpleHTTPServer

Emulate a mail server using python

python -m smtpd -n -c DebuggingServer localhost:1025

Colored and comfortable alternative to top

if not installed: sudo apt-get install htop
 
htop

Colorize Logs

Three different tools to solve this: multitail, grc, ccze

Installation:

sudo apt-get install multitail grc ccze

multitail:

multitail logfile

grc:

grc tail -f logfile

ccze:

tail -f logfile | ccze -m ansi // or html or curses

SQL

Count unique / all values

SELECT COUNT(DISTINCT <FIELDNAME>), COUNT(ALL <FIELDNAME>) FROM <TABLE>;

Partially anonymize e-mail addresses

UPDATE <TABLE_NAME>
SET <EMAIL_FIELD>=
  INSERT(
    <EMAIL_FIELD>,
    POSITION('@' IN <EMAIL_FIELD>),
    100,
    CONCAT(FLOOR(1 + (RAND() * 100)),'@hascode.com'))
  WHERE
    POSITION('@' IN <EMAIL_FIELD>)>0;

Find duplicate entries

SELECT COUNT(*), <FIELDNAME> FROM <TABLENAME>
GROUP BY <FIELDNAME>
HAVING COUNT(*)>1;

Oracle Multiple Levels of Subtotals

SELECT <FIELD>, <otherfield..>
FROM <TABLE>
GROUP BY ROLLUP(<FIELD>);

Postgres create roles

CREATE ROLE name;
DROP ROLE name;
SELECT rolname FROM pg_roles;
\du
GRANT name TO username

Postgres set user password

ALTER USER
ALTER USER root WITH password 'xxx';

Postgres change database

\cDBNAME

Java

Show processes

jps

Create heap dump from running process

jmap -dump:format=b,file=/tmp/heap.bin 2381

Use SLF4J and Logback

Maven dependencies:

<project>
    <properties>
        <logback.version>1.0.3</logback.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.6.6</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>${logback.version}</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>${logback.version}</version>
        </dependency>
    </dependencies>
</project>

Example logback.xml:

<configuration>
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
        </encoder>
    </appender>
    <root level="debug">
        <appender-ref ref="STDOUT"/>
    </root>
</configuration>

Service Discovery using ServiceLoader

interface MyService {}
class MyServiceImpl {}
class AnotherMyServiceImpl {}
 
ServiceLoader<MyService> serviceLoader = ServiceLoader.load(MyService.class);
for (MyService s : serviceLoader) {
    System.out.println(s);
}

Dynamic Proxy

package com.hascode.sample;
 
public interface SampleService {
    String printInformation();
}
 
package com.hascode.sample;
 
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
 
public class SampleServiceInvocationHandler implements InvocationHandler {
    @Override
    public Object invoke(final Object proxy, final Method method, final Object[] args) throws Throwable {
        return "test";
    }
}
 
package com.hascode.sample;
 
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;
 
public class Main {
    public static void main(String[] args) {
        InvocationHandler handler = new SampleServiceInvocationHandler();
        SampleService service = (SampleService) Proxy.newProxyInstance(SampleService.class.getClassLoader(), new Class[]{SampleService.class}, handler);
        System.out.println(service.printInformation());
    }
}

JAX-RS return a generic list in a Response

List list = new ArrayList();
GenericEntity> entity = new GenericEntity>(list) {};
Response response = Response.ok(entity).build();

JAX-RS / Jersey – Return a JSON Array for a Collection with a single element

Lets say you’re mapping a collection of books e.g. List<Book> books using jaxb passed as a jaxrs Response .. you may encounter a situation where you receive the following JSON output if there are many books in the collection:

{
	books:[
		{id:1, title:"foo"},
		{id:2, title:"bar"}
	]
}

But if there is only one book in the collection your receive a single JSON object instead of an array .. e.g.:

{
	books:{
		id:1, title:"foo"
	}
}

The solution is to provide a custom JAXBContext ContextResolver and advise the context always to render arrays here:

import javax.ws.rs.ext.ContextResolver;
import javax.ws.rs.ext.Provider;
import javax.xml.bind.JAXBContext;
 
import com.sun.jersey.api.json.JSONConfiguration;
import com.sun.jersey.api.json.JSONJAXBContext;
 
import com.hascode.entity.Book;
 
@Provider
public class BookContextResolver implements ContextResolver<JAXBContext> {
        private final JAXBContext context;
        private final Class[] types = { Book.class };
 
        public PersonContextResolver() throws Exception {
                this.context = new JSONJAXBContext(JSONConfiguration.mapped().arrays("books").build(), Book.class);
        }
 
        @Override
        public JAXBContext getContext(final Class<?> objectType) {
                for (Class type : types) {
                        if (type == objectType) {
                                return context;
                        }
                }
                return null;
        }
}

Create heap dump on OutOfMemoryError

-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/path/to/save/dumps

Scala

SBT – Eclipse Plugin

Add to your ~/.sbt/plugins/plugins.sbt

addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "2.1.1")

Apache Webserver

Deny all methods excepting POST and GET

RewriteCond %{REQUEST_METHOD} ^(TRACE|TRACK|OPTIONS|HEAD)
RewriteRule .* - [F]

Rewrite all aliases for a domain to a single domain

RewriteEngine On
RewriteCond %{HTTP_HOST} ^(www\.)?mydomain1\.com [NC,OR]
RewriteCond %{HTTP_HOST} ^(www\.)?mydomain2\.com [NC,OR]
RewriteCond %{HTTP_HOST} ^(www\.)?mydomain3\.com [NC,OR]
RewriteRule (.*) http://mydomain.com/$1 [R=301,L]

Maven

Colourize output

export MAVEN_COLOR=true

Run build with 4 threads

mvn -T 4 clean install

Run build with 2 threads per core

mvn -T 2C clean install

Adjust java source/target version for compiler

<build>
    <plugins>
        <plugin>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>1.6</source>
                <target>1.6</target>
            </configuration>
        </plugin>
    </plugins>
</build>

Javascript / jQuery

Firebug XPath Testing Build in

$x("//div/span/em");

Create a custom jQuery selector

The following selector matches all elements with a width greater than 200px. Just run the example on a website like jQuery.com in the Firebug console.

$.extend($.expr[':'], {
    widthGT200Pixels: function(elem) {
        return $(elem).width() > 200;
    }
});
 
$('div:widthGT200Pixels').css('border','1px solid red').click(function() {
    alert('The width of this div exceeds 200px');
});

Afterscriptexecute Event

Allows to hook into the execution of every script tag in a page

<script type="text/javascript">
document.addEventListener('afterscriptexecute', function(e){
  console.log('exec script:', e.target);
}, false);
</script>

jQuery function to center an element

jQuery.fn.center = function () {
    return this.css('position','absolute')
               .css('top', ( $(window).height() - this.height() ) / 2+$(window).scrollTop() + 'px')
               .css('left', ( $(window).width() - this.width() ) / 2+$(window).scrollLeft() + 'px');
}
 
// centering an element
$('#jq-footerNavigation').center();

Cascading Stylesheets / CSS

Calculations

Firefox

Configure address bar to return search results

Enter about:config in the address bar
Search for the key keyword.url
Modify the value for your search engine of choice .. e.g. for the google search: http://www.google.com/search?q=

Eclipse

Favorites

Spare my time when using static imports ..

Window > Preferences > Java > Editor > Content Assist > Favorites:

com.google.common.collect.Lists
 
com.jayway.restassured.matcher.RestAssuredMatchers
 
com.jayway.restassured.RestAssured
 
org.hamcrest.MatcherAssert
 
org.hamcrest.Matchers
 
org.mockito.Mockito

Template to insert a static logger instance

Go Windows > Preferences > Java > Editor > Templates > New …

Enter logger as name and as template: private static final Logger log = LoggerFactory.getLogger(${enclosing_type}.class);

Afterwards you’re able to type logger in your code and ctrl+space gives the option to insert the logger

Atlassian

Disable YUI compressor

<plugin>
    <groupId>com.atlassian.maven.plugins</groupId>
    <artifactId>maven-jira-plugin</artifactId>
    <version>${amps.version}</version>
    <extensions>true</extensions>
    <configuration>
        <compressResources>false</compressResources>
        [..]
    </configuration>
</plugin>

Confluence – Get favourites by user

Using the label manager.

List getFavouriteSpaces(String username)

Confluence – Determine the base URL

Using the SettingsManager:

String baseUrl = settingsManager.getGlobalSettings().getBaseUrl();

Confluence – Get the context path

Using the BootstrapManager:

String contextPath = bootstrapManager.getWebAppContextPath();

Confluence – Using Velocity Template for a Macro

final VelocityContext contextMap = new VelocityContext(MacroUtils.defaultVelocityContext());
 
contextMap.put("key", obj); // references obj as variable named $key in the velocity template
 
VelocityUtils.getRenderedTemplate("path/to/template.vm", contextMap);

Confluence – Perform a content search with restrictions

final SearchManager searchManager // <- injected
final SearchQuery inSpacesQuery = new InSpaceQuery("DS");
final SearchQuery contentTypeQuery = new ContentTypeQuery(ContentTypeEnum.ATTACHMENT);
final SearchQuery query = BooleanQuery.andQuery(inSpacesQuery,contentTypeQuery);
final SearchSort searchSort = new CreatedSort(Order.DESCENDING);
final SearchFilter contentPermissionFilter = ContentPermissionsSearchFilter.getInstance();
final SearchFilter spacePermissionFilter = SpacePermissionsSearchFilter.getInstance();
final SearchFilter permissionsFilter = new ChainedSearchFilter(contentPermissionFilter, spacePermissionFilter);
final ResultFilter maxResultFilter = new SubsetResultFilter(20);
final ISearch search = new ContentSearch(query, searchSort,permissionsFilter, maxResultFilter);
final SearchResults results = searchManager.search(search);

Reference exported Web Resources like CSS/JS in a Velocity Template

Include this directive in the velocity template:

#requireResource("PLUGINKEY:WEBRESOURCEKEY")

Example declaration of a web resource in the atlassian-plugin.xml:

<web-resource name="Some Web Resources" i18n-name-key="some-web-resources.name" key="WEBRESOURCEKEY">
    <description key="some-web-resources.description">Some Web Resources</description>
    <resource name="some.css" type="download" location="somepath/some-min.css"/>
</web-resource>

Webworks/XWorks Action – Rendering a template without the page frame

Applying the parameter decorator=popup or decorator=none is one option.

Another option is to specify the decorator in the velocity template’s header section

<head>
	<meta name="decorator" content="atl.popup" />
</head>

Stash – Enable a Package Logger via REST

curl -u admin -v -X PUT -d "" -H "Content-Type: application/json" http://localhost:7990/stash/rest/api/latest/logs/logger/com.hascode/debug

JIRA – Find existing locations for web-items and web-sections

Their declarations can be found in <source-installation-directory>/jira-project/jira-components/jira-core/src/main/resources/webfragment/system-user-nav-bar-sections.xml

Confluence – Search for Spaces by Space Label

Label label ...
 
List spaces = labelManager.getSpacesWithLabel(label);
 
or
 
List spaces = labelManager.getSpacesWithLabel("labelString", Namespace.GLOBAL);

Confluence – Read User Details

for (String group : userDetailsManager.getProfileGroups()) {
 
System.err.println(“Group: ” + group + ” has keys:”);
 
for (String key : userDetailsManager.getProfileKeys(group)) {
 
System.err.println(“key: ” + key + ” / current user’s value: ” + userDetailsManager.getStringProperty(currentUser, key));
 
}
 
}
 
Group: personal has keys:
 
key: phone / current user’s value: 1234
 
key: im / current user’s value: -
 
key: website / current user’s value: www.hascode.com
 
Group: business has keys:
 
key: position / current user’s value: CTO
 
key: department / current user’s value: Technologies
 
key: location / current user’s value: Wiesbaden

ActiveObjects Create Entity with NotNull Constraint

The entity:

public interface Book extends Entity {
 
 [..]
 
 @NotNull
 
 String getTitle();
 
}

Create a new book entity:

ActiveObjects ao; // -> set via dependency injection
 
Book book = ao.create(Book.class, new DBParam("TITLE", "some title"));

Git

Show changes in a dedicated date range

git log --since=4.days --until=3.days

Git setup a server using the git protocol

cd projectdir
git daemon --reuseaddr --base-path=. --export-all --verbose
git clone git://ipaddress/ appname

Misc

Data Normalizing

newVal = (oldVal-min) / (max-min)

Ugly Scala Example

package com.hascode
import scala.collection.mutable.LinkedList
 
object NormalizerExample extends App {
  val dataSet = LinkedList(1., 6.5, 3., 6.2, 20., 31.2, 50.2, 12., 0.24, 1.224, 2.2, 3.)
  for ((num, index) <- dataSet.zipWithIndex) {
    dataSet(index) = (num - dataSet.min) / (dataSet.max - dataSet.min)
  }
  println("Normalized: " + dataSet)
}

Normalized: LinkedList(0.01521216973578863, 0.12921819759798853, 0.05947594797769014, 0.12324029048767723, 0.3982240175619966, 0.6213992163469515, 1.0, 1.0, 0.07531115879828326, 0.40498283261802576, 0.7319742489270387, 1.0)

XML / XSLT / XPath / Schema

XSLT Strip Namespaces for Output

<xsl:stylesheet version="1.0" 
       xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
       xmlns:foo="http://foo" 
       xmlns:bar="http://bar" 
       exclude-result-prefixes="foo bar">