Grub2 where is grub.conf

Files with a leading numeral are executed first, beginning with the lowest number. If files with alphabetic names are present, they are executed after the numerically-named files. Only executable files generate output to grub. Sets environmental variables such as system file locations, display settings, themes, and previously saved entries. Normally you do not need to make changes to this file. Identifies Linux kernels on the root device and creates relevant menu entries.

This includes the associated recovery mode option if enabled. Only the latest kernel is displayed on the main menu page, with additional kernels included in a submenu. There are sections to identify specific other operating systems, such as Windows or macOS. This file provides a simple way to include custom boot entries into grub. The processing sequence is set by the preceding numbers with the lowest number being executed first. If scripts are preceded by the same number the alphabetical order of the complete name decides the order.

GRUB 2 utilities create a temporary device map on the fly, which is usually sufficient, particularly in the case of single-disk systems. The following example changes the mapping to make DISK 3 the boot disk. Being able to directly edit menu entries is useful when the system does not boot anymore because of a faulty configuration.

It can also be used to test new settings without altering the system configuration. Add space-separated parameters to the end of the line starting with linux or linuxefi to edit the kernel parameters.

Or edit the general options to change for example the kernel version. Press F10 to boot the system with the changes you made or press Esc to discard your edits and return to the GRUB 2 menu. Changes made this way only apply to the current boot process and are not saved permanently.

The US keyboard layout is the only one available when booting. See Figure To add boot options, select an entry and start typing. Additions you make to the installation boot entry will be permanently saved in the installed system.

Even before the operating system is booted, GRUB 2 enables access to file systems. Users without root permissions can access files in your Linux system to which they have no access after the system is booted. To block this kind of access or to prevent users from booting certain menu entries, set a boot password. If set, the boot password is required on every boot, which means the system does not boot automatically.

Proceed as follows to set a boot password. After you reboot, you will be prompted for a user name and a password when trying to boot a menu entry.

Enter root and the password you typed during the grub2-mkpasswd-pbkdf2 command. If the credentials are correct, the system will boot the selected boot entry. It can also limit access to specific entries for specific users, and can encrypt plain-text passwords for increased security. Custom Menu Entries GRUB 2 allows users to create customized menu selections which will be automatically added to the main menu when sudo update-grub is executed.

Any other plaintext editor Vim, Emacs, Kate, Leafpad is fine too. After that, reboots and shutdowns should start working properly. Its menu can be customized by the user to present a more visually-appealing menu by changing font colors, backgrounds and resolutions. Theme elements will include colors, fonts, progress indicators, menus, and labels.

Both of these hold great promise but are not ready for release with Ubuntu 9. Check the Links section at the bottom of this page for references. Information concerning upgrades from GRUB 0. Security Preventing booting via Grub command-line The ability to manually boot using the Grub command-line constitutes the biggest security risk in Linux. Placing passwords or locking menu items in the Grub configuration files does not prevent a user from booting manually using commands entered at the grub command-line.

Once a foreign OS is booted, of course, it can be used to access any part of an unencrypted hard drive. There are currently no options to prevent the command-line usage of Grub. Partners Support Community Ubuntu. On BIOS-based machines, issue the following command as root :. On UEFI-based machines, issue the following command as root :.

Menu entries are also automatically added to the boot menu when updating the kernel. This file can be edited or copied.

Note that as a minimum, a valid menu entry must include at least the following:. If you do not want menu entries to be updated automatically, you can create a custom menu. Rebuild the grub. Run the grub2-setpassword command as root:. With this change, modifying a boot entry during booting requires you to specify the root user name and your password.

Setting a password using the grub2-setpassword prevents menu entries from unauthorized modification but not from unauthorized booting. To also require password for booting an entry, follow these steps after setting the password with grub2-setpassword :. If you forget your GRUB 2 password, you will not be able to boot the entries you reconfigure in the following procedure. Delete the --unrestricted parameter from the menu entry block, for example:.

Now even booting the entry requires entering the root user name and password. Therefore, to retain password protection, use the above procedure after every use of grub2-mkconfig. The grub2-setpassword tool was added in Red Hat Enterprise Linux 7. Booting entries without the --unrestricted parameter requires the root password.

However, GRUB 2 also enables creating additional non-root users that can boot such entries without providing a password. Modifying the entries still requires the root password.

Reinstalling GRUB 2 is a convenient way to fix certain problems usually caused by an incorrect installation of GRUB 2, missing files, or a broken system. Other reasons to reinstall GRUB 2 include the following:. When using the grub2-install command, the boot information is updated and missing files are restored. Note that the files are restored only if they are not corrupted.

Use the grub2-install device command to reinstall GRUB 2 if the system is operating normally. For example, if sda is your device :. When using the yum reinstall grub2-efi shim command, the boot information is updated and missing files are restored.

Use the yum reinstall grub2-efi shim command to reinstall GRUB 2 if the system is operating normally. This method completely removes all GRUB 2 configuration files and system settings. Apply this method to reset all configuration settings to their default values. Removing of the configuration files and subsequent reinstalling of GRUB 2 fixes failures caused by corrupted files and incorrect configuration.

To do so, as root , follow these steps:. For EFI systems only , run the following command:. Perform the GRUB upgrade for these reasons:. Make sure that the grub2 package has been installed. If grub2 is not on the system after the upgrade to RHEL 7, you can install it manually by running:.

If the system boots using EFI, install the following packages if they are missing:. Do not overwrite the old GRUB configuration file by mistake in the next step. This section applies only to the legacy BIOS booting. Remove the identified boot entry. The following command removes the boot entry from the example above:. If you have more than one such boot entry, remove all identified old boot entries.

This is due to the fact that installation of packages across major releases is not supported. This section describes how to configure GRUB 2 for serial communications on machines with no display or keyboard. To access the GRUB 2 terminal over a serial connection, an additional option must be added to a kernel definition to make that particular kernel monitor a serial connection.

A much higher baud rate, for example , is preferable for tasks such as following log files. To set the system to use a serial terminal only during a single boot process, when the GRUB 2 boot menu appears, move the cursor to the kernel you want to start, and press the e key to edit the kernel parameters. Remove the rhgb and quiet parameters and add console parameters at the end of the linux16 line as follows:.

For example, to update the entry for the default kernel, enter a command as follows:. The --update-kernel parameter also accepts the keyword ALL or a comma separated list of kernel index numbers. The first line disables the graphical terminal. On the second line, adjust the baud rate, parity, and other values to fit your environment and hardware.

The screen tool serves as a capable serial terminal. To install it, run as root :. By default, if no option is specified, screen uses the standard baud rate. Verizon Selling PS5. Windows 11 SE Explained.

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