Category Archives: Technology

How do I send email from the linux command line?

10/15/2013 Mark Jacobsen Leave a comment

Need to email from your linux command line? Assuming the underlying pieces are configured correctly (run the 1st example to see) here are the basics…

Send a test email

mail -s "Hi there" someone@somewhere.com

Include some body text…

echo "This is some body text" | mail -s "Hi there" someone@somewhere.com

Email the contents of a file to someone…

mail -s "My Subject" someone@somewhere.com < /path/to/your/file.txt

You can find more here

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Disclaimer: Thoughts and opinions are my own, and do not reflect the views of any employer, family member, friend, or anyone else. Some links may be affiliate links, but I don't link to anything I don't use myself.

DB2

How can I be getting a deadlock trying to create a stored proc?

09/23/2013 Mark Jacobsen Leave a comment

If you’re getting an error similar to the following…

SQL0911N The current transaction has been rolled back because of a deadlock 
or timeout. Reason code "68". LINE NUMBER=171. SQLSTATE=40001

… and you know your tables are all just fine, it may be that someone (likely a DBA) has the SYSCAT.ROUTINES table locked up. Try running this…

SELECT RTRIM(R.ROUTINESCHEMA),RTRIM(R.SPECIFICNAME),RTRIM(R.ROUTINENAME) 
FROM SYSCAT.ROUTINES R 
WHERE R.ROUTINETYPE='P'  
ORDER BY RTRIM(R.ROUTINESCHEMA), RTRIM(R.SPECIFICNAME), RTRIM(R.ROUTINENAME)

…and if that errors, try running “WITH UR”. Assuming the 1st fails and the 2nd does not, have your neighborhood DBA kill any connections that may be causing the lock.

Linux

What timezone is my linux server configured for?

09/19/2013 Mark Jacobsen Leave a comment

To find out, just run the following command from the shell…

date +%Z

Linux

How do I run a script in the background?

09/17/2013 Mark Jacobsen Leave a comment

Use nohup! Here’s an example…

nohup /some/script.ksh

And even better, to redirect all output to a specific location…

nohup /home/user/script.ksh > /home/user/script.log 2>&1 &

Yes, the ” 2>&1 &” at the end is important.

DB2

DB2 Incremental Delete

07/15/2013 Mark Jacobsen Leave a comment

Ever have to delete a lot of records from a table in DB2 and can’t truncate, but you keep filling the transaction log? One way of solving the problem without having to manually update ranges of values in a where clause is to do an incremental delete in a stored proc. Here’s an example/template to get you started…


WHILE EXISTS (  SELECT  ITEM_ID 
		FROM    XX.TABLE
		WHERE   SOMETHING_NB = 1
		FETCH FIRST 1 ROWS ONLY )
DO
	DELETE FROM 
		(SELECT ROW_NUMBER() OVER() AS ROW_NB
		FROM    XX.TABLE
		WHERE   SOMETHING_NB = 1
		FETCH FIRST 20000 ROWS ONLY)
	WHERE ROW_NB <= 20000;
	
	IF ((L_SQLCODE_NB <> 0) AND (L_SQLCODE_NB <> 100)) THEN
		SIGNAL SQLSTATE '20003' SET MESSAGE_TEXT = 'Error deleting records';
	END IF; 
	
	COMMIT;
END WHILE;

Java

Resolving Ant javac “class file has wrong version” issues

07/03/2013 Mark Jacobsen Leave a comment

Ever run an ANT build in eclipse and it works just fine, but as soon as you run it outside of eclipse you get something like…

class file has wrong version 51.0, should be 49.0

The issue is likely that you need to “fork” in your javac task…

Before (with error)

javac srcdir="${build.path}" 
   verbose="true" 
   includeantruntime="false" 
   includejavaruntime="false"

After (no error)

javac srcdir="${build.path}" 
   verbose="true" 
   includeantruntime="false" 
   includejavaruntime="false" 
   fork="yes"

Hopefully this can save you about 2 hours some day!

Java

New cffreedom-utils repo on github

05/07/2013 Mark Jacobsen Leave a comment

For the last 10 years or so I’ve built up a number of Java utility functions and classes to help me write code easier. Over time I’ve probably had to re-write many of the functions as I’ve moved teams, lost the code, or just wanted to make it better. I’ve also had to jar up and help other developers use the code one too many times. Since I’m finally sick of that I’ve switch over to Maven for dependency and build management, moved the library to github, and am open sourcing the development so that others can take advantage of my work, and contribute to it to make it better.

You can find the project at https://github.com/communicationfreedom/cffreedom-utils. Please take a look, and consider helping make it even better.

Note: Since I’ve been using the project more and more the pace of change is pretty steep and the package structure has been changing frequently, but I believe that is starting to settle down a bit.

Java

XPath Query Not Returning any Results in Java

03/25/2013 Mark Jacobsen Leave a comment

In looking over documentation on XPath queries it seemed easy enough to be able to pull out values from XML, but try as I might I kept getting no results back. Even searching on the root element “/elementName” didn’t return any results. Of course, as with all things Java there’s a trick and that trick is to call setNamespaceAware(). Here’s a quick and dirty example…


DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(false); // NEVER FORGET THIS
DocumentBuilder builder = domFactory.newDocumentBuilder();
XPathFactory factory = XPathFactory.newInstance();
XPath xpath = factory.newXPath();
XPathExpression expr = xpath.compile("/items/item[@id='2']");
return (NodeList)expr.evaluate(domDocument, XPathConstants.NODESET);

Java

Output a DOM Document as XML using Java

03/23/2013 Mark Jacobsen Leave a comment

Ok, here’s another nerdy post for all the java developers out there. Hopefully it saves you some time.

Let’s say you have a XML DOM Document that you’ve been modifying in your code, and now want to write it back out as XML. One would think there would be a nice toXml() method or something on the Document, but there isn’t. Instead, make sure you have the xalan.jar file on your class path and use this function…


public static String getDomDocumentAsXml(org.w3c.dom.Document domDocument)
{
	try
	{
		TransformerFactory tf = TransformerFactory.newInstance();
		Transformer transformer = tf.newTransformer();
		transformer.setOutputProperty(OutputKeys.INDENT, "yes");
		StreamResult xmlOutput = new StreamResult(new StringWriter());
		transformer.transform(new DOMSource(domDocument), xmlOutput);
		return xmlOutput.getWriter().toString();
	}
	catch (Exception e) { e.printStackTrace(); return null; }
}

Linux, Productivity, Windows

Setting up the ultimate console

02/15/2013 Mark Jacobsen Leave a comment

If you’ve been coding for any time, chances are you’ve become acquainted with the command line. While some love it and some hate it I think it’s wonderful for getting things done quickly. Unfortunately, the windows command line is crap. With that said I finally got fed up and asked that most important programmer question of “How do I get a better command line”?

That search led me to an open source application called appropriately enough: Console. When I first opened it up and started playing around I have to admit my first reaction was “meh”. Then I asked that import question again, “How can this be made better”? A little Googling and experimentation later I got things working to my satisfaction.

So, here for your one-stop quick-reference is how to setup the ultimate console for Windows…

Assumptions

You access the console for all different platforms (not just Windows)
You already have putty and its utilities downloaded – and are familiar with their use
You already have installed cygwin – and are familiar with its use

Installation

Download Console and extract the contents to the folder of your choice
Download ANSICON and extract the following files to the same directory you extracted Console to.
- ANSI32.dll
- ANSI64.dll
- ansicon.exe

Great, now you have Console installed, but this is the configuration I use to make it really rock.

Configuration

These can all be found under “Edit -> Settings”

Appearance
- Custom color: Change it to an awsome green
Appearance -> More…
- Uncheck “Show toolbar”
- Select “Alpha” under “Window transparency” and set “Active window” to 25 and “Inactive window” to 40
Behavior
- Check “Copy on select”
- Uncheck “Clear selection on copy”
Hotkeys
- Set “New Tab 1” to “Ctrl+T”
- Set “Copy selection” to “Ctrl+C”
- Set “Paste” to “Ctrl+V”
Hotkeys -> Mouse
- Set “Copy/clear selection” to “None”
- Set “Select text” to “Left”
- Set “Paste text” to “Right”
- Set “Context menu” to “Middle”

Tab Configuration

Now that you have your console looking pretty and being functional, lets hook it into putty and cygwin. You can do this configuration under “Edit -> Settings -> Tabs”. Obviously, the directories you’ve chosen for things will be different (change to your values).

Cygwin: Add a tab and set the shell to:

C:\cygwin\bin\bash.exe --login -i

Putty: Add a tab and set the shell to:

C:\apps\Console2\ansicon.exe "C:\apps\Putty\plink.exe" -load "aSavedSessionName"

Reference