GRUB INSTALLATION
Opensource platforms are of the best playground for computer enthusiasts. I would like to quote some of my experiments, the issues encountered when working with Linux systems. The most common problem happens to multiboot enthusiasts is the grub boot loader. Most of the cases after installing a Windows operating system on a Linux machine, the boot menu disappears. Earlier, because of ignorance most of the people will go for a fresh installation of Linux systems to recover the boot menu. I came to know about this when I tired of many attempts of reinstallation. If you have a dual boot system with Ubuntu OS, you can recover the boot menu by just installing the grub to master boot recorder. This is the following procedure for installing.
Boot the system with the help of bootable pen drive loaded with Ubuntu OS.
Select the option to try Ubuntu. Do not select the installation option.
In the search bar, type Terminal.
In the Terminal, prompt $sudo su
$fdisk -l
find out the partition where you installed Linux, it can be sda3 or sda4 etc.
$mount /dev/sda4 /mnt
$mount --bind /dev /mnt/dev
$mount --bind /proc /mnt/proc
$cp /etc/resolv.conf /mnt/etc/resolv.conf
$chroot /mnt
$grub-install --recheck /dev/sda (here do not give any numbers to 'sda'. It is to be 'sda' itself. This is the first device or master boot recorder)
$reboot
Enjoy!! you can view your old boot menu with boot options. In case of Debian. you need to make the bootable pendrive with Debian operating system.
Once I encountered a scenario on my laptop which connected with battery and booting. The laptop is HP Probook 440. The battery is inbuilt and you need to dismantle the laptop to replace the battery. After the replacement of battery, the laptop failed to boot up. It showed only a message at the bottom which says "PRESS ESCAPE KEY". I tried various key options to make it bootable. But every attempt went in vain. Finally, I headed for grub installation. I tried with Ubuntu Startup Disk Creator for making bootable Debian 9.5 iso. But it failed. Later I downloaded "rufus.exe" in windows and made a bootable Pendrive with Debian 9.5 iso. The bios entry to HP laptop can be done by pressing F10 key before booting. After plugging the pen drive, restart the system. Go to bios by pressing F10. Go to the advanced settings and uncheck the legacy boot order. At this time you can view the pen drive in the booting list. Press F10 and select yes to reboot. The system will boots into the OS in the pendrive. In the graphical menu, go to advanced settings and rescue mode. There are options in the rescue menu to install the grub to master boot recorder. Select that option. you need to select the drive where Linux is installed. Finally, you need to give the device where the grub needs to be installed. Usually, for a dual boot system, the device to install grub is master boot recorder which is otherwise labeled as '/dev/sda' only. Do not put any numbers after sda. After performing this step you can go for rebooting the system and you will be happy to see your old boot menu with the members.
For a fresh installation of Debian, you can follow the following link Debian Installation
ANACONDA JUPYTER PYTHON ERROR
One of the common error in Jupyter framework is the selection of python compiler. Sometimes we need to reinstall all the default packages in Debian or Ubuntu in Jupyter framework also. To avoid such scenario there is one excellent tip. Instead of reinstalling the packages, it is possible to give the path of default python installed in the system. For performing this, we need to locate the directory where anaconda is installed. Usually, it will be installed in /home. .local/share/anaconda etc. locate the folder named kernel specs. The kernel spec file will be different for different versions of python. Locate the kernel.json file and locate the path in JSON file. Change that path to the default python path. The default python path can be obtained with the help of command whereis python.