Reviving a 4‑Year‑Old Ubuntu PC: Network Fixes, SSH Setup, Java, Maven & More

Fix Ubuntu 14.04 NetworkManager incompatibility

When the system reports that the network services are incompatible with the installed NetworkManager, execute the following commands as root:

sudo -s
cd /etc/NetworkManager/
ls -la
mv system-connections /home/username/   # move the directory to the user’s home
mkdir /system-connections
reboot

Connect to RuiJie campus network (rjsupplicant)

Authenticate with the campus client and restart NetworkManager if the interface disappears:

cd rjsupplicant
sudo ./rjsupplicant.sh -d 0 -u username -p password
# if the network interface disappears
cd /etc/init.d/
sudo start network-manager

Install and enable OpenSSH server

sudo apt-get update
sudo apt-get install openssh-server

Configure Vim to use four‑space tabs

Add the following lines to ~/.vimrc:

set ts=4
set expandtab

Install Oracle JDK 8 and set environment variables

# Extract the archive
sudo tar -zxvf jdk-8u72-linux-x64.tar.gz
# Move to /opt
mv jdk1.8.0_72 /opt/
# Edit /etc/profile and append:
JAVA_HOME=/opt/jdk1.8.0_72
JRE_HOME=$JAVA_HOME/jre
PATH=$PATH:$JAVA_HOME/bin
CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export JAVA_HOME JRE_HOME PATH CLASSPATH
# Reload profile
. /etc/profile
# Verify installation
java -version

Install Apache Maven and add it to PATH

Edit ~/.zshrc (or ~/.bashrc) and add:

export M2_HOME=/opt/software/apache-maven-3.5.0
export M2=$M2_HOME/bin
export PATH=$M2:$PATH

Sublime Text Chinese input fix (InputHelper plugin)

Clone the plugin and install its dependency:

cd ~/.config/sublime-text-3/Packages
git clone https://github.com/xgenvn/InputHelper.git
sudo apt-get install python-gtk2-dev   # required if Ctrl+Shift+Z does not open the input box

GRUB boot entry for legacy machine

linux (hd0,1)/vmlinuz.efi root=/dev/sda3
initrd (hd0,1)/initrd.lz
boot

After editing the GRUB configuration, update the bootloader:

sudo update-grub
sudo grub-install /dev/sda

Install useful desktop utilities

sudo add-apt-repository ppa:nilarimogard/webupd8
sudo apt-get update
sudo apt-get install albert cairo-dock zeal indicator-sysmonitor

Upgrade Ubuntu 17.04 and switch to Tsinghua mirrors

Replace /etc/apt/sources.list with the following entries (Ubuntu Xenial repositories):

deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted universe multiverse

Then run the release upgrade:

sudo do-release-upgrade -d

Resolve missing sound after upgrade on NVIDIA GPU systems

Ensure the NVIDIA driver is not active and the GPU/audio chip are powered:

# Check current driver
prime-select query
# If it returns "nvidia", switch to Intel and reboot
sudo prime-select intel
reboot
# Verify GPU power state
lspci -H1 | grep 01:00
# If the first line ends with (rev ff), power the GPU
echo ON > /proc/acpi/bbswitch
# If the audio chip line is missing, suspend and resume the laptop, then re‑run the check
# Unload NVIDIA driver if still loaded
sudo rmmod nvidia   # or echo 1 > /sys/bus/pci/devices/0000:01:00.0/remove
# Rescan PCI bus
echo 1 > /sys/bus/pci/rescan
# Verify audio chip appears
lspci | grep 01:00.1
# Switch GPU mode back as needed
prime-select intel   # or prime-select nvidia
# Log out and back in, then list audio devices
aplay -l

Install Zsh and Oh‑My‑Zsh

sudo apt-get install curl git zsh
sh -c "$(curl -fsSL https://raw.github.com/robbyrussell/oh-my-zsh/master/tools/install.sh)"

The above commands provide a concise set of procedures to restore networking, install development tools, configure the desktop environment, and troubleshoot post‑upgrade issues on an older Ubuntu workstation.