GNU/Linux

Install Oracle Java JDK on Linux

java

In this post we will find out how to install the official Oracle Java JDK on Linux.

First, you need to download the correct package for your operating system.
Go here and download the Linux .tar.gz file for x86 or x64 platform.

At the time of writing this article, the current available version is Java SE Development Kit 8u74.

Now, copy the file you just downloaded to the folder /usr/local/java by doing

sudo cp -r FILE_NAME /usr/local/java/

Now unpack the archive using this command

sudo tar xvzf FILE_NAME

Wait for the extraction to be completed, then remove the .tar.gz archive.

Now, to let the JDK folder be system-wide available, we need to add it to the PATH. To do this, let’s run this command

sudo gedit /etc/profile

and at the end of the file past these lines

JAVA_HOME=/usr/local/java/DIR_NAME
PATH=$PATH:$JAVA_HOME/bin
export JAVA_HOME
export PATH

where DIR_NAME is the name of the directory which was created when you extracted the .tar.gz archive.

Now let’s reload our changes by running

source /etc/profile

and it’s done!

If everything went out correctly you should be able to run

java -version

and see your current installed Java version!

Happy development!

GNU/Linux

Assign static device name using udev rules

How can you assign static device name using udev rules to a USB device? Why do you need it?

Imagine you made a script which refers to a particular device you could plugin trough USB port: sometimes this device could be mounted as /dev/sdb1, sometimes as /dev/sdc1, and so on. You may need a static reference to it because you didn’t know which name it will use.

Another scenario could be a startup mount of a drive as discussed in http://www.w3ma.com/mount-ntfs-partition-startup/

To achieve this, let first discover some attributes of our device using the command

sudo lsusb

We will receive an output like this:

emanuele@ubuntu:~$ lsusb

Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Bus 008 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

Bus 001 Device 004: ID 1058:107c Western Digital Technologies, Inc.

Have a look at the Western Digital Technologies row, this is the device we are looking for: 1058 is the Vendor ID and 107c is the Product ID! We will use these information to uniquely identify our device.

Now, let’s create a new udev rule typing

sudo nano /etc/udev/rules.d/99-my_rules.rules

and writing the following into the file

ACTION==”add”, ATTRS{idVendor}==”1058″, ATTRS{idProduct}==”107c”, SYMLINK+=”my_wd_usb_hd”

where the ATTRS numbers are the ones we discovered before, while my_wd_usb_hd is the name we choose for our device.

Now let’s reboot our pc! Everytime it reboots this rule will be applied and we will always find our device under /dev/my_wd_usb_hd

GNU/Linux

Mount NTFS partition at startup

In this post we will learn how to mount NTFS partition at startup in a very simple way.

You can use the following command to retrieve a list of your partitions and their UUID.

ls -l /dev/disk/by-uuid

Pick the one you want to automatically mount and open the file /etc/fstab by using

sudo nano /etc/fstab

Add a new row like:

UUID=XXXXXXXXXXX  /hd_mount_point       ntfs-3g defaults        0       0

where XXXXXXXXXXX is your partition UUID and /hd_mount_point is a folder on your disk you will use to access that partition.

Simply reboot and you are done!

GNU/Linux

Force Ubuntu boot after power failure

Hello,

in this blog post I will show a little trick to avoid your Ubuntu installation got stuck on GRUB boot menu waiting for you to choose an option after a power failure.

To force Ubuntu boot you can edit your /etc/default/grub with your favourite text editor, e.g. running this command from your terminal:

nano /etc/default/grub

and then add this line in the file:

GRUB_RECORDFAIL_TIMEOUT=0

Afterwards, remember to run:

sudo update-grub

Next time your pc will have a power failure it will reboot without getting stuck on GRUB!