Tech Notes – Page 40 – Kev's Development Toolbox

May 31, 2015

Local javac path issues on older OpenShift WildFly8.2 based project

I have an app that I created a few months back on OpenShit based on the WildFly 8.2 cartridge. Locally in Eclipse the project builds and compiles fine, but executing mvn directly or in Netbeans (which also builds using your mvn pom.xml), it fails with an error regarding a path to javac:

-------------------------------------------------------------
COMPILATION ERROR : 
-------------------------------------------------------------
Failure executing javac, but could not parse the error:
/bin/sh: ${env.OPENSHIFT_WILDFLY_DIR}usr/lib/jvm/jdk1.8.0_05/bin/javac: bad substitution

1 error

This is obviously setup for building specifically in the OpenShift environment with this property defining the path to javac:

<maven.compiler.executable>${env.OPENSHIFT_WILDFLY_DIR}usr/lib/jvm/jdk1.8.0_05/bin/javac</maven.compiler.executable>

There’s a few posts and discussions about this (e.g. here and I suspect this is related), but I’m guessing the version of the pom.xml I have is older and been changed recently. I created a new OpenShift WildFly based project to compare the created pom.xml, and these two properties are no longer in the pom.xml file:

<maven.compiler.executable>${env.OPENSHIFT_WILDFLY_DIR}usr/lib/jvm/jdk1.8.0_05/bin/javac</maven.compiler.executable>
<maven.compiler.fork>true</maven.compiler.fork>

Removing them fixes my local builds, and pushing the code to OpenShift still seems to build ok too.

May 27, 2015

Mounting Linux ext partitions on OS X

I wanted to check some files on an SD Card formatted in ext that I had used on my Pi and wanted to check if I had left some files in the home dir before I reimaged it. OS X doesn’t support ext formatted drives by default, but you add support using OSXFuse.

Install Fuse for OS X
Install the ext plugin for Fuse
Find the partition you want to mount with: diskutil list
Make a mount point – not sure on Mac OS X where is the best place, but I added /mnt/sdcard
Mount with:

[code]sudo fuse-ext2 /dev/disk1s2 /mnt/sdcard[/code]
(replace with the /dev/ to your device)

I’m not sure if it’s best practice on the Mac to mount with sudo, but this worked for me for what I needed to do. Fuse mounts on ext are r/o by default, but there is experimental r/w support that can be enabled, check the docs.

Done!

May 17, 2015

node.js process.cwd() “no such file or directory” starting http-server

When starting the node.js http-server, I got this error:

[code]Error: ENOENT, no such file or directory
at Error (native)
at Function.startup.resolveArgv0 (node.js:720:23)
at startup (node.js:63:13)
at node.js:814:3[/code]

From the post here, it seems this error can occur if you attempt to start the server in a dir that’s already been deleted. In my case I had renamed a folder that contained the folder where I was attempting to start the server. cd’d up a couple and into the new/renamed folder, and problem solved.

May 11, 2015

JEP 222 – REPL proposed for Java SE9

A REPL (Read-Eval-Print-Loop) feature is becoming a common feature for many languages (Scala and Groovy both have a REPL commandline shell), and JEP-222 proposes adding this same feature to Java for SE9. This feature is useful for quickly trying out and evaluating an expression, and will be a valuable addition to Java SE.