Tag Archives: Linux

When you hit GRUB console on boot in an ASUS VivoMini UN45 with Ubuntu 18.04

Posted by on January 10, 2021 No comments

I have an ASUS VivoMini that I run Ubuntu 18.04 on as a place for databases, Docker containers, and other stuff. Every now and then it boots me into GRUB console on reboots.

I’m here going to show how I use to solve is:

grub> set root=(hd0,2)
grub> linux /boot/vmlinuz-4.15.0-112-generic root=/dev/nvme0n1p2
grub> initrd /boot/initrd.img-4.15.0-112-generic
grub> boot

Explanation:
set root=(hd0,2) sets the disk an partition where the Linux installation is. Here is the first drive (hd0) and the second partition (2)
linux /boot/vmlinuz-4.15.0-112-generic root=/dev/nvme0n1p2 here I set the Linux kernel and the root path. It’s where I usually mess up. Most guides tell you to use /dev/sdaX (or sdbX or similar). The problem is that I use an internal Intel SSD witch identifies as nvme0 and not sda2, so when I try to use sda2 I get: “Gave up waiting for root file system /dev/sda2 does not exist. Dropping to shell”, but when I use nvme0n1p2 it works (nvme0n1p2 means first disk (n1) and second partition (p2))
initrd /boot/initrd.img-4.15.0-112-generic sets the initrd file. This has to be the same version as the vmlinux version
boot simply boots the system with the settings above. If all goes well we should reach the Ubuntu login screen (or console)

To make the changes permanent (until the next power outage or other misfortune) 

sudo update-grub

This will collect all data from the settings above and create a grub.cfg file. I needed sudo on my system, maybe you don’t. After we have created a new grub.cfg file we need to install it on the disk boot sector (not on a partition so no number for disk or partition here). For me, this was done by:

sudo grub-install /dev/nvme0

The system should now behave again 🙂

Tested on Ubuntu 18.04, GRUB 3.0, and Linux kernel 4.15.0-112

Run multiple Linux commands, one after the other

Posted by on October 19, 2020 No comments

Run commands after another
Ex. 

mkdir temp & cd temp & ls

Run commands after another if the previous command SUCCEEDS
Ex. 

mkdir temp && cd temp && ls

Run commands after another if the previous command FAILS
Ex. 

mkdir temp || echo 'mkdir failed'

My Play Framework Systemd script

Posted by on December 27, 2018 No comments

Ubuntu deprecated Upstart so I had to turn to Systemd for my app controls in Ubuntu 18.04. In this script I set 2 environment variables (HOME and LANG), change directory to the app directory and starts the Play Framework application

# Myapp systemd script
#
# Location:/lib/systemd/system/myapp.service
#
# Useful commands:
#
# Start Myapp: 		systemctl start myapp.service
# Stop Myapp:		systemctl stop myapp.service
# Restart Myapp:	systemctl restart myapp.service
# Show status:		systemctl status myapp.service
# Enable start on boot:	systemctl enable myapp.service
# Disable start on boot:systemctl disable myapp.service
#
# List all services running: systemctl
# Check config: systemd-analyze verify myapp.service
#
####################################################################################

[Unit]
Description=Job that runs my app daemon

[Service]
Type=forking
Environment=HOME=/opt/myapp/app
Environment=LANG=en_US.UTF-8
ExecStartPre=/bin/bash -c 'cd /opt/myapp/app'
ExecStart=/bin/bash -c 'bin/myapp -J-Xms256M -J-Xmx768m -J-server -Dhttp.port=80 -Dconfig.file=conf/application.conf -Dlogger.file=conf/application-logger.xml'

[Install]
WantedBy=multi-user.target

The arguments for the Play service are what I normally use for AWS. You might need other settings

Tested on Ubuntu 18.04 and Play Framework 2.3