Category: Programming

Quick-Start and Minimal Cheat Sheet for Chef and Test Kitchen

Posted on by rchapin

Following is a quick-start for getting a Chef and Test Kitchen environment set up to start writing and testing Chef cookbooks.  This is an work in progress, so please if you find something that is incorrect or does not work as expected, send me an e-mail.

Development Environment Set-up:

Unless you are a Ruby developer and already have a complete environmenet set-up the easiest thing to do is to install the Chef Development Kit, https://downloads.chef.io/chef-dk/.

After downloading and → Continue reading “Quick-Start and Minimal Cheat Sheet for Chef and Test Kitchen”

Perl One-Liner for Replacing Multiple Lines of a Text file With Multiple Lines of Text

Posted on by rchapin

When executing ‘search-and-replace’ commands on ASCII under Linux, Unix (or *nix) operating systems, sed works or most cases and makes for reasonably straightforward reading of the script.

If  you want to replace multiple lines of text with multiple lines of text, following is a perl one-liner that does the trick and is much easier to wrangle than trying to do it in sed.

perl -i -pe "BEGIN{undef $/;} s:${EXISTING_LINES}:${REPLACEMENT_TEXT}:smg" file.txt
→ Continue reading “Perl One-Liner for Replacing Multiple Lines of a Text file With Multiple Lines of Text”

Adding the Contents of a Source File to the Beginning of a Target File

Posted on by rchapin

Following is *nix a command that you can use to add the contents of a source text file to the start of another text file (the source file).

echo -e '0r <source_file_name\nw' | ed -s <target_file_name
→ Continue reading “Adding the Contents of a Source File to the Beginning of a Target File”

Updating all of the pom.xml Version Numbers in a Multi-Module Maven Project

Posted on by rchapin

To update the versions of all of the poms in a multiple module project use the versions-maven plugin.

To update

mvn versions:set -DnewVersion=1.4.0-SNAPSHOT

Will modify all of the versions of each of the poms to the version specified.  It will create a pom.xml.versionsBackup for each pom file that it modified.  You can then examine each to make sure that it is as you intended.

If you want, you can revert your change with

mvn versions:revert

If you are satisfied with → Continue reading “Updating all of the pom.xml Version Numbers in a Multi-Module Maven Project”

Use awk to Print from nth element to the End of the Line

Posted on by rchapin

If you want to extract from the nth token to the end of the line, following is how you can do that with awk:

Given a source file with the following:

line1 -- 01   0011 1
line2 -- 01   0011 2
line3 -- 01   0011 3
line4 -- 01   0011 4
line5 -- 01   0011 5
line6 -- 01   0011 6
line7 -- 01   0011 7
line8 -- 01   0011 8
line9 -- 01   0011 9
line10 -- 01   0011
→ Continue reading “Use awk to Print from nth element to the End of the Line”

JVM Option for Increasing the Default Number of Lines in the StackTrace

Posted on by rchapin

By default (Java 1.6 or greater), the JVM will output, at most, 1024 lines of the stack trace.

In the situation where you have some recursion problem or some infinite loop that results in a stack overflow error you will need to increase this value with a JVM option to see the origin of your crash.

To do so, add the following option to the java command

$ java -XX:MaxJavaStackTraceDepth=-1 -jar some.jar some.package.Class  etc, etc,

-1 indicates no limit.  Any → Continue reading “JVM Option for Increasing the Default Number of Lines in the StackTrace”

Debugging Maven Tests by Connecting an IDE to the Maven JVM

Posted on by rchapin

In some instances you cannot reproduce a failure or condition running a test in an IDE that manifests itself when you run it on your build server or via maven on the command line.

In that case, it is very helpful to be able to remotely attach your IDE to the running maven process and then step through the code.

To do so you will need to:

Execute maven on  the command line as follows (adding any additional -D args → Continue reading “Debugging Maven Tests by Connecting an IDE to the Maven JVM”

Error attaching to process: sun.jvm.hotspot.debugger.DebuggerException: Can’t attach to the process [SOLVED]

Posted on by rchapin

If you are attempting to use jmap or another Java memory analysis tool to connect to a running JVM to generate a heap dump, even when running jmap as the same user as that of the running process, and encounter the following error:

Attaching to process ID 2712, please wait...
Error attaching to process: sun.jvm.hotspot.debugger.DebuggerException: Can't attach to the process

Following is the (likely) solution to your problem.

It is likely that the ptrace_scope setting for your system is set → Continue reading “Error attaching to process: sun.jvm.hotspot.debugger.DebuggerException: Can’t attach to the process [SOLVED]”

Generate a Random String of a Specified Size with a Shell Script

Posted on by rchapin

The following is a one-liner for generating a random string of a fixed size in bash, where the possible characters to use in the string are any digit, letter, and a newline.

By adding the newline, you are fairly sure to prevent getting one long line of text.

< /dev/urandom tr -dc "[:digit:][:alpha:][\n]" | head -c1000 file.out
→ Continue reading “Generate a Random String of a Specified Size with a Shell Script”

Connecting To a Test Kitchen Instance Via SFTP, SSH, or SCP

Posted on by rchapin

If you are using Chef and Test Kitchen to test your cookbooks you may have need to connect to the Test Kitchen VM in some other fashion other than $ kitchen login instance-name.

To do so:

Do a $ kitchen list to see the running vms

kitchen list
Instance                      Driver   Provisioner  Verifier  Transport  Last Action
default-centos-66             Vagrant  ChefSolo     Busser    Ssh        Converged

Then look in the .kitchen directory from where you ran your $ kitchen command and look for the corresponding → Continue reading “Connecting To a Test Kitchen Instance Via SFTP, SSH, or SCP”

© 2005 Ryan Chapin