- Choose the manager who will control the Boot (GRUB or BCD) and install the systems in the proper order to minimize problems.
- Set the default and timeout from Windows (Boot and Recovery), editing GRUB or with tools like EasyBCD/EasyUEFI.
- If something goes wrong, rebuild the menu (update-grub) or repair the BCD; always have a recovery medium.
The bootloader is the menu that appears just after the POST and before any operating system is loaded., allowing you to choose between the different installed OSes. In Windows, these entries are stored in the Boot Configuration Database (BCD), while in most distros Linux The manager is GRUB, very flexible and compatible.
When there is only one system, you will usually not see any menus.; the manager directly starts the single OS. When another system is detected (another Windows, Linux, etc.) an entry is added and the selector is displayed. Ideally, you'd be able to define a default and a timeout in case you don't touch anything.
To work comfortably in dual boot, it is advisable that the chosen manager detects all the systems well and allows you to customize the order and ThereOn Linux, GRUB stands out for its compatibility and options. On Windows, its own manager is adequate, although it sometimes requires tweaking after major updates.
Recommended order when installing multiple systems
The easiest way is to install each system on a separate disk.. So each one places its manager on its own drive, and you can choose from the disk order in the UEFI/BIOS or the motherboard's boot menu.
If everything is on the same disk, install the systems one by one, leaving the one you want to control the boot for last.For example, if you plan to use GRUB, install Windows first and then your Linux distro (Ubuntu, Debian, etc.) so that GRUB detects the rest and becomes active.
If you prefer Windows Manager, end up with the latest version of Windows (for example, after setting up a coexistence with older versions or with Linux in between). You can then adjust its BCD and the default.
After each installation, it is good practice to “refresh” the bootloader to detect new things: on Linux with update-grub/update-grub2, and on Windows by checking BCD or using a utility like EasyBCD.
Editing the command in Linux with GRUB (by hand)
If you use GRUB as the boot manager (as usual in Linux), you have full control over the boot order and time.. User configuration is done in / Etc / default / grub and then the final menu is “compiled”.
You can open and edit the file with your favorite editor. (graphical interface or terminal). For example:
Recommended command (graphical editor): sudo gedit /etc/default/grub
Alternative command (terminal): sudo nano /etc/default/grub
Some older guides cite paths like “/etc/default/grub.cfg” or use “gksu gedit /etc/default/grub.cfg”; note that The file you need to edit is /etc/default/grub, and the generated menu file is /boot/grub/grub.cfg (not directly editable). If you see examples with lines like these, they'll help you understand what to change:
# Si cambias este archivo, ejecuta update-grub para actualizar /boot/grub/grub.cfg
GRUB_DEFAULT=0
GRUB_TIMEOUT=10
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""
The key is GRUB_DEFAULT: indicates which input starts by default. Entries are numbered from 0, so if you want the “third” in the list to start you must put 2 (0, 1, 2). GRUB_TIMEOUT marks the number of seconds to wait before launching the default.
object lesson (fictional list):
- 0: Debian 11
- 1: Debian Recovery
- 2: Windows 10
To boot Windows 10 by default, set GRUB_DEFAULT=2. When you're done making your changes, save and run:
GRUB Update: sudo update-grub
In some distros you will also see: sudo update-grub2. Both regenerate the menu and apply the new order and timeout.
Grub Customizer: Change the order with a graphical interface
If you prefer not to edit files, Grub Customizer gives you a clear interface to move, rename or delete entries, and even edit advanced content.. Works with GRUB, GRUB2 and BURG.
Most distributions offer it in repositoriesTypical installation on Debian/Ubuntu and derivatives:
Install Grub Customizer: sudo apt install grub-customizer
After applying changes with Grub Customizer, remember that the necessary files are also regenerated.. If something goes wrong, You can rebuild the list with update-grub/update-grub2 to make everything coherent.
Troubleshooting common problems
I deleted an entry by mistake
On windows, recreate it with BCD tools (native or with EasyBCD). On Linux, if the problem is that an OS no longer appears in GRUB, rebuild the menu sudo update-grub o sudo update-grub2.
I see a duplicate operating system
On windows, check in msconfig > Boot y eliminates redundant input. In GRUB, remove or disable one of the entries from Grub Customizer or adjusting the scripts that generate the menu, and regenerate with update-grub.
After updating Windows, GRUB disappeared and I can't enter Linux.
It is relatively common that after a major update, Windows replaces the loader and GRUB does not appear.. Boot into a Live media of your distro, enter recovery mode, and reinstall GRUB.:
Reinstall GRUB (example): sudo grub-install /dev/sdX (replace X with the correct disk) and then sudo update-grub.
Upon reboot you should get back the menu with Linux and Windows. If you keep Windows as manager and prefer that path, re-inject the Linux entry into the BCD (for example, with EasyBCD) and check that it starts properly.
Passionate writer about the world of bytes and technology in general. I love sharing my knowledge through writing, and that's what I'll do on this blog, show you all the most interesting things about gadgets, software, hardware, tech trends, and more. My goal is to help you navigate the digital world in a simple and entertaining way.