BASH IO Redirection

In bash, by default, only stdout gets redirected to a file when you use the ">" operator.

To redirect stderr to a file, use the "2>" operator.

To redirect both, use "&>"

Reference:http://www.cyberciti.biz/faq/redirecting-stderr-to-stdout/

Git Undo Staging a File for Commit

If a file has already been staged for commit i.e. via the "git add" command, use the following command to unstage the file:

git reset HEAD <filename>

Iterating Through All Loggers & Appenders in LogBack

Most people probably won't need it, but when you do, this will come in handy.

http://stackoverflow.com/questions/7064402/is-it-possible-to-find-logback-log-files-programmatically

The "spi" Package in Java Projects

It's quite common to find a package called "spi" in Java projects.

Here's an explanation of what it means and what it's for:

• http://stackoverflow.com/questions/2954372/difference-between-spi-and-api

C# Iterate Dictionary

Using "foreach" and "KeyValuePair" as the element. Refer to this: http://stackoverflow.com/questions/141088/what-is-the-best-way-to-iterate-over-a-dictionary-in-c

C# Start New Process

This is how it's done:http://stackoverflow.com/questions/258416/shellexecute-equivalent-in-net

If you need to start multiple processes asynchronously, you'd need to first start multiple threads and then within each thread, each process is started.

Reference for this: http://www.codeproject.com/Articles/25983/How-to-Execute-a-Command-in-C

How to add arguments: http://msdn.microsoft.com/en-sg/library/system.diagnostics.processstartinfo.arguments.aspx

C# Getting Time Since Epoch

Many things are simpler in C# than e.g. in Java, but getting the Epoch time is an exception, and this is how it's done.

TimeSpan timeSpan = DateTime.UtcNow - new DateTime(1970, 1, 1); double currentTime = timeSpan.TotalSeconds;

Ubuntu: Configuring Tomcat

Instead of hacking the startup scripts, some of the common configuration variables can be set in Ubuntu in the file "/etc/default/tomcat7"

Git Log Show File List

To list the files that were involved in each commit:

git log --name-status

References:

• http://stackoverflow.com/questions/1230084/how-to-have-git-log-show-filenames-like-svn-log-v

Git Checkout File From Branch

To checkout a file from a specific branch:

git checkout <branchname> <filepath>

References:

• http://stackoverflow.com/questions/8423136/netbeans-git-copy-individual-files-between-branches
• http://stackoverflow.com/questions/307579/how-do-i-copy-a-version-of-a-single-file-from-one-git-branch-to-another

iOS How to Close an App

With multi-tasking, apps no longer really close when you press the home button. It stays in the background and the OS automatically closes them when the device is low on memory and when it thinks the app is unlikely to be used in the near future. To force it to close for e.g. development testing purpose, follow the instructions on this page: http://support.apple.com/kb/ht5137

AWS DynamoDB Java API Gotcha

If you don't set the end-point, it will default to the US East Virginia region, resulting in an error saying the table can't be found.

The error message you'll get varies. If you have IAM setup to limit access for the user account to this specific DynamoDB table, then you'll get an "AccessDeniedException". Otherwise, you'll get a "ResourceNotFoundException".

If your DynamoDB is configured in the other regions, you'll have to set the End Point after creating the client e.g:

client = new AmazonDynamoDBClient(awsCredentials); client.setEndpoint("https://dynamodb.ap-southeast-1.amazonaws.com");

AWS DynamoDB ARN for IAM

To give access via IAM to a specific DynamoDB resource, define the ARN as follows:

arn:aws:dynamodb:<region>:<accountID>:table/<tablename>

AWS IAM Account ID

The account ID is needed to construct the ARN for IAM entries. AWS isn't being very clear about how to retrieve the account ID. It's actually the Account Number (with the hypens removed) that you see under your name in the "Manage Your Account" page (accessed via the "My Account" link in a drop down menu under your name on the top-right of the console).

Mac Show Hidden Files in Finder

I usually don't need this feature, as I can use the Terminal to work with hidden files, but when I needed to restore some hidden files from Time Machine, I needed to get Finder to show hidden files.

Here's a couple of links showing how it's done:

• http://howto.cnet.com/8301-11310_39-20062357-285/how-to-access-hidden-files-to-restore-in-time-machine/
• http://meinit.nl/restore-hidden-files-apple-mac-os-x-time-machine

iOS Simulator: View Files

If you ever need to look into the filesystem of an iOS Simulator to e.g. test file download features, here are some information as to how it's done:

• http://stackoverflow.com/questions/6480607/is-there-any-way-to-see-the-file-system-on-the-ios-simulator
• http://idevhub.com/where-is-the-iphone-simulator-filesystem-stored/

Jersey Server Binary File

To serve a binary file such as a ZIP file with a REST service in Jersey, use the following:

@GET @Produces("application/zip") @Path("{itemId}") public Response downloadItem(@PathParam("itemId") int itemId){    String fileName = "item" + itemId + ".zip";    StreamingOutput streamingOutput = new StreamingOutput(){        public void write(OutputStream output) throws IOException, WebApplicationException {            // write data to output stream here        }            };        return Response.ok(streamingOutput, "application/zip").header("content-disposition","attachment; filename = "+fileName).build(); }

Uploading Files to S3 With Ant

This is becoming more and more relevant as S3 is increasingly being used for deployment of software in the cloud.

This is the one I'm currently using.
https://github.com/corley/aws-ant-task
Apparently it's still being actively maintained.

Question on StackOverflow about this: http://stackoverflow.com/questions/3782157/ant-tasks-for-amazon-ec2-s3

Using Hibernate Query Cache in Spring

The steps for configuring the EHCache query cache is the same as when not using Spring. The main difference is how queries is being indicated as cacheable. In Spring, queries are made via the a subclass DAO of the HibernateDaoSupport class, which provides a method to indicate whether all queries in the DAO should use the query cache.

This should be called in the initDao method.

@Override    protected void initDao() throws Exception {        super.initDao();        // this enables the usage of query cache for all queries in this DAO        this.getHibernateTemplate().setCacheQueries(true);        // the cache region name that should be used for this entity        this.getHibernateTemplate().setQueryCacheRegion(“XXXXXXX”);        // optional, for enabling statistics collection for profiling        this.getHibernateTemplate().getSessionFactory().getStatistics().setStatisticsEnabled(true);    }

Note that this is for the query cache, not the second-level cache, the latter which is used for "get" operations.

Cocos2D: Z Order

The higher the number, the closer the object is to the viewer.

The lower the number, the further the object is to the viewer.