GRUB

https://www.gnu.org/software/grub/manual/grub/
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GRUB (Grand Unified Bootloader) is a bootloader package from the GNU Project that allows users to...
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### fwsetup

Source: https://www.gnu.org/software/grub/manual/grub/grub

Reboots the computer into the firmware setup menu or checks if the firmware supports a setup menu.

```APIDOC
## fwsetup

### Description
Reboots the computer into the firmware setup menu. If the '--is-supported' option is specified, it checks whether the firmware supports a setup menu and exits successfully if it does.

### Method
POST (Implicit - command execution)

### Endpoint
N/A (Command-line utility)

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Command Usage
`fwsetup [--is-supported]`

### Response
#### Success Response
- If `fwsetup` is run without `--is-supported`: The system reboots into the firmware setup.
- If `fwsetup --is-supported` is run: The command exits successfully (exit code 0) if the firmware supports a setup menu.

#### Error Response
- If `fwsetup --is-supported` is run and the firmware does not support a setup menu: The command exits with a non-zero exit code.
```

--------------------------------

### Start Software TPM (swtpm) Instance

Source: https://www.gnu.org/software/grub/manual/grub/grub

Initializes and starts a software TPM (swtpm) instance for testing TPM2 functionality. Creates a state directory and logs control messages.

```bash
# mkdir swtpm-state
# swtpm chardev --vtpm-proxy --tpmstate dir=swtpm-state \
             --tpm2 --ctrl type=unixio,path="swtpm-state/ctrl" \
             --flags startup-clear --daemon > swtpm.log
```

--------------------------------

### Example BLS Config File (GRUB)

Source: https://www.gnu.org/software/grub/manual/grub/grub

An example configuration file for a Boot Loader Specification (BLS) entry used by GRUB. This file defines parameters such as title, kernel path, and boot options.

```ini
# /boot/loader/entries/6a9857a393724b7a981ebb5b8495b9ea-3.8.0-2.fc19.x86_64.conf
title        Fedora 19 (Rawhide)
sort-key     fedora
machine-id   6a9857a393724b7a981ebb5b8495b9ea
version      3.8.0-2.fc19.x86_64
options      root=UUID=6d3376e4-fc93-4509-95ec-a21d68011da2 quiet
architecture x64
linux        /6a9857a393724b7a981ebb5b8495b9ea/3.8.0-2.fc19.x86_64/linux
initrd       /6a9857a393724b7a981ebb5b8495b9ea/3.8.0-2.fc19.x86_64/initrd
```

--------------------------------

### Install GRUB to Floppy Disk

Source: https://www.gnu.org/software/grub/manual/grub/grub

Installs the GRUB bootloader to a floppy disk. This involves mounting the floppy, creating a boot directory, installing GRUB, and then unmounting.

```shell
# mount -t ext2 /dev/fd0 /mnt
# mkdir /mnt/boot
# grub-install --boot-directory=/mnt/boot /dev/fd0
# umount /mnt
```

--------------------------------

### GRUB Block List Syntax Example

Source: https://www.gnu.org/software/grub/manual/grub/html_node/Block-list-syntax

This example demonstrates the syntax for specifying a block list in GRUB. It shows how to define multiple block ranges using offsets and lengths. Omitted offsets default to zero, and omitted lengths extend to the end of the device.

```text
0+100,200+1,300+300,800+
```

--------------------------------

### Start GRUB Emulator with TPM2 Device

Source: https://www.gnu.org/software/grub/manual/grub/grub

Launches the GRUB emulator, connecting it to the specified TPM2 software device for testing.

```bash
# grub-emu --tpm-device $tpm2dev
```

--------------------------------

### Example BLS Configuration File for GRUB

Source: https://www.gnu.org/software/grub/manual/grub/html_node/blscfg

An example of a Boot Loader Specification (BLS) configuration file used by GRUB. This file defines boot entry parameters such as title, sort-key, machine-id, kernel version, boot options, architecture, and paths to the kernel and initrd images.

```shell
# /boot/loader/entries/6a9857a393724b7a981ebb5b8495b9ea-3.8.0-2.fc19.x86_64.conf
title        Fedora 19 (Rawhide)
sort-key     fedora
machine-id   6a9857a393724b7a981ebb5b8495b9ea
version      3.8.0-2.fc19.x86_64
options      root=UUID=6d3376e4-fc93-4509-95ec-a21d68011da2 quiet
architecture x64
linux        /6a9857a393724b7a981ebb5b8495b9ea/3.8.0-2.fc19.x86_64/linux
initrd       /6a9857a393724b7a981ebb5b8495b9ea/3.8.0-2.fc19.x86_64/initrd

```

--------------------------------

### GRUB Configuration: Timeout Style Example

Source: https://www.gnu.org/software/grub/manual/grub/grub

Demonstrates setting the GRUB timeout style to 'countdown'. In this mode, GRUB displays a countdown before showing the menu, offering an alternative to the standard menu display or immediate boot.

```shell
GRUB_TIMEOUT_STYLE=countdown
```

--------------------------------

### Define GRUB Menu Entry with ID

Source: https://www.gnu.org/software/grub/manual/grub/html_node/Simple-configuration

This example shows how to define a GRUB menu entry for a GNU/Linux distribution. It includes a class and a unique identifier, 'example-gnu-linux', which can be used to set this entry as the default.

```grub
menuentry 'Example GNU/Linux distribution' --class gnu-linux --id example-gnu-linux {
	...
}
```

--------------------------------

### Get Help for grub-script-check

Source: https://www.gnu.org/software/grub/manual/grub/html_node/Invoking-grub_002dscript_002dcheck

Displays a summary of available command-line options for grub-script-check. This is useful for understanding the program's capabilities and usage.

```bash
grub-script-check --help

```

--------------------------------

### GRUB Configuration for Multi-booting

Source: https://www.gnu.org/software/grub/manual/grub/html_node/Multi_002dboot-manual-config

This snippet defines GRUB menu entries for various operating systems and installers. It demonstrates how to load different OS configurations, including legacy GRUB, Windows, FreeBSD, and live installers for Fedora and Debian. It utilizes GRUB's search command to locate partitions by label and specifies kernel and initrd images for installers.

```grub
menuentry "OS using grub2" {
   insmod xfs
   search --set=root --label OS1 --hint hd0,msdos8
   configfile /boot/grub/grub.cfg
}

menuentry "OS using grub2-legacy" {
   insmod ext2
   search --set=root --label OS2 --hint hd0,msdos6
   legacy_configfile /boot/grub/menu.lst
}

menuentry "Windows XP" {
   insmod ntfs
   search --set=root --label WINDOWS_XP --hint hd0,msdos1
   ntldr /ntldr
}

menuentry "Windows 7" {
   insmod ntfs
   search --set=root --label WINDOWS_7 --hint hd0,msdos2
   ntldr /bootmgr
}

menuentry "FreeBSD" {
          insmod zfs
          search --set=root --label freepool --hint hd0,msdos7
          kfreebsd /freebsd@/boot/kernel/kernel
          kfreebsd_module_elf /freebsd@/boot/kernel/opensolaris.ko
          kfreebsd_module_elf /freebsd@/boot/kernel/zfs.ko
          kfreebsd_module /freebsd@/boot/zfs/zpool.cache type=/boot/zfs/zpool.cache
          set kFreeBSD.vfs.root.mountfrom=zfs:freepool/freebsd
          set kFreeBSD.hw.psm.synaptics_support=1
}

menuentry "experimental GRUB" {
          search --set=root --label GRUB --hint hd0,msdos5
          multiboot /experimental/grub/i386-pc/core.img
}

menuentry "Fedora 16 installer" {
          search --set=root --label GRUB --hint hd0,msdos5
          linux /fedora/vmlinuz lang=en_US keymap=sg resolution=1280x800
          initrd /fedora/initrd.img
}

menuentry "Fedora rawhide installer" {
          search --set=root --label GRUB --hint hd0,msdos5
          linux /fedora/vmlinuz repo=ftp://mirror.switch.ch/mirror/fedora/linux/development/rawhide/x86_64 lang=en_US keymap=sg resolution=1280x800
          initrd /fedora/initrd.img
}

menuentry "Debian sid installer" {
          search --set=root --label GRUB --hint hd0,msdos5
          linux /debian/dists/sid/main/installer-amd64/current/images/hd-media/vmlinuz
          initrd /debian/dists/sid/main/installer-amd64/current/images/hd-media/initrd.gz
}
```

--------------------------------

### List Configured Network Interfaces (GRUB)

Source: https://www.gnu.org/software/grub/manual/grub/grub

The `net_ls_addr` command lists all currently configured network interfaces, displaying their MAC addresses and assigned IP addresses. This is useful for verifying network setup.

```grub
-- Command: net_ls_addr
     List all configured interfaces with their MAC and IP addresses.
```

--------------------------------

### Generate Netbootable Directory with grub-mknetdir

Source: https://www.gnu.org/software/grub/manual/grub/grub

This command generates a netbootable directory structure required for network booting GRUB. It takes the target network directory, a subdirectory for GRUB files, and a platform-specific directory as input. The example shows its usage for the i386-pc platform.

```bash
grub-mknetdir --net-directory=/srv/tftp --subdir=/boot/grub -d /usr/lib/grub/<platform>
```

```bash
grub-mknetdir --net-directory=/srv/tftp --subdir=/boot/grub -d /usr/lib/grub/i386-pc
```

--------------------------------

### Booting GNU/Linux with GRUB

Source: https://www.gnu.org/software/grub/manual/grub/grub

This snippet demonstrates booting GNU/Linux using GRUB. It includes commands for setting the root device, loading the kernel with optional parameters, and loading an initrd if necessary. It also shows the difference between 'linux' and 'linux16' commands.

```grub
grub> search --set=root --file /vmlinuz
grub> linux /vmlinuz root=/dev/sda1
grub> linux /vmlinuz root=/dev/sda1 acpi=off
grub> linux16 /vmlinuz root=/dev/sda1 acpi=off
grub> initrd /initrd
grub> initrd16 /initrd
grub> boot
```

--------------------------------

### Get Version Information for grub-script-check

Source: https://www.gnu.org/software/grub/manual/grub/html_node/Invoking-grub_002dscript_002dcheck

Prints the version number of the GRUB software. This option is helpful for verifying the installed GRUB version.

```bash
grub-script-check --version

```

--------------------------------

### Set GRUB root device for NetBSD (GPT)

Source: https://www.gnu.org/software/grub/manual/grub/html_node/NetBSD

Sets the GRUB root device for a NetBSD installation using a GUID Partition Table (GPT). It first loads the 'part_gpt' module and then sets the root to the third GPT partition on the first hard disk (hd0,gpt3).

```grub
insmod part_gpt
set root=(hd0,gpt3)
```

--------------------------------

### Booting NetBSD with GRUB

Source: https://www.gnu.org/software/grub/manual/grub/grub

This snippet illustrates booting NetBSD from GRUB. It covers setting the root device for both BSD disk labels and GPT, loading the kernel with 'knetbsd', and optionally loading kernel modules using 'knetbsd_module_elf'.

```grub
grub> insmod part_bsd
grub> set root=(hd0,netbsd1)
grub> insmod part_gpt
grub> set root=(hd0,gpt3)
grub> knetbsd /netbsd
grub> knetbsd /netbsd -s -v
grub> knetbsd_module_elf /stand/amd64/6.0/modules/ffs/ffs.kmod
grub> boot
```

--------------------------------

### Install GRUB Manually

Source: https://www.gnu.org/software/grub/manual/grub/html_node/Multi_002dboot-manual-config

This command installs a self-compiled GRUB bootloader to a specified boot directory. It's used when manually configuring GRUB for multi-booting, ensuring GRUB is installed to a dedicated partition mounted at /mnt/boot. The command requires root privileges and the target device path.

```bash
grub-install --boot-directory=/mnt/boot /dev/sda
```

--------------------------------

### Install GRUB to EFI Removable Media

Source: https://www.gnu.org/software/grub/manual/grub/grub

Installs GRUB to removable media on an EFI system. Requires the '--removable' flag along with specifying both '--efi-directory' and '--boot-directory'.

```shell
# grub-install --efi-directory=/mnt/usb --boot-directory=/mnt/usb/boot --removable
```

--------------------------------

### Install GRUB to USB with BIOS Bug (USB-FDD)

Source: https://www.gnu.org/software/grub/manual/grub/grub

Installs GRUB to a USB drive when the BIOS incorrectly identifies it as a floppy. This method uses a loop device and a specific boot directory for compatibility.

```shell
# losetup /dev/loop0 /dev/sdb1
# mount /dev/loop0 /mnt/usb
# grub-install --boot-directory=/mnt/usb/bugbios --force --allow-floppy /dev/loop0
```

--------------------------------

### Booting GNU/Hurd with GRUB

Source: https://www.gnu.org/software/grub/manual/grub/grub

This snippet shows how to boot the GNU/Hurd operating system using GRUB. It involves setting the root device, loading the kernel and necessary modules, and finally initiating the boot process.

```grub
grub> search --set=root --file /boot/gnumach.gz
grub> multiboot /boot/gnumach.gz root=device:hd0s1
grub> module  /hurd/ext2fs.static ext2fs --readonly \
                           --multiboot-command-line='${kernel-command-line}' \
                           --host-priv-port='${host-port}' \
                           --device-master-port='${device-port}' \
                           --exec-server-task='${exec-task}' -T typed '${root}' \
                           '$(task-create)' '$(task-resume)'
grub> module /lib/ld.so.1 exec /hurd/exec '$(exec-task=task-create)'
grub> boot
```

--------------------------------

### Install GRUB to EFI Fixed Disk

Source: https://www.gnu.org/software/grub/manual/grub/grub

Installs GRUB to a fixed disk on an EFI system. If the EFI System Partition is mounted at '/boot/efi', no special arguments are needed. Otherwise, '--efi-directory' must be specified.

```shell
# grub-install
# grub-install --efi-directory=/mnt/efi
```

--------------------------------

### Xen VM Configuration and GRUB Boot Entry Example

Source: https://www.gnu.org/software/grub/manual/grub/html_node/Passing-environment-variables-through-Xen

Demonstrates how to configure a Xen virtual machine's configuration file to pass environment variables to GRUB and how to use these variables within the guest's GRUB configuration file to modify boot parameters.

```xenconfig
# In the Xen configuration file for the guest
name = "linux_vm"
type = "pvh"
kernel = "/path/to/grub-i386-xen_pvh.bin"
extra = "xen_grub_env_linux_append='loglevel=3'"
memory = 1024
disk = [ "file:/srv/vms/linux_vm.img,sda,w" ]

```

```grub
# In the guest's GRUB configuration file
menuentry "Linux VM with dom0-specified kernel parameters" {
    search --set=root --label linux_vm --hint hd0,msdos1
    linux /boot/vmlinuz root=LABEL=linux_vm ${xen_grub_env_linux_append}
    initrd /boot/initrd.img
}

```

--------------------------------

### GRUB Configuration File Search Order for Network Booting

Source: https://www.gnu.org/software/grub/manual/grub/grub

GRUB searches for its configuration file in a specific order when booting from the network. The search prioritizes files named after the client's UUID, MAC address, and IP address, falling back to a generic grub.cfg. This order ensures specific configurations are applied when available.

```grub.cfg
(FWPATH)/grub.cfg-(UUID OF MACHINE)
(FWPATH)/grub.cfg-01-(MAC ADDRESS OF NIC)
(FWPATH)/grub.cfg-(IPv4 OR IPv6 ADDRESS)
(FWPATH)/grub.cfg
```

--------------------------------

### Start GRUB Emulator with Software TPM Device

Source: https://www.gnu.org/software/grub/manual/grub/html_node/TPM2-key-protector

This command starts the GRUB emulator ('grub-emu') and configures it to use the software TPM instance by specifying the character device path obtained from the swtpm log.

```bash
# `grub-emu --tpm-device $tpm2dev`
```

--------------------------------

### Configure BIOS Boot Partition with parted

Source: https://www.gnu.org/software/grub/manual/grub/html_node/BIOS-installation

This command demonstrates how to set a partition as a BIOS boot partition using the 'parted' utility. It's crucial for GPT installations where GRUB is placed in a dedicated partition. Ensure the correct partition number is specified.

```bash
# `parted /dev/disk set partition-number bios_grub on`
```

--------------------------------

### Install Signed GRUB Image on PReP Partition

Source: https://www.gnu.org/software/grub/manual/grub/html_node/Signing-GRUB-itself

This command installs a signed GRUB image to the PReP partition, specifically for the powerpc-ieee1275 architecture. It uses the `dd` command to copy the signed image file to the specified partition. Ensure the target partition is correctly identified.

```bash
# Install signed GRUB image to the PReP partition on powerpc-ieee1275

dd if=core.elf.signed of=/dev/sda1
```

--------------------------------

### Load Stock Early Initrd Images for Linux

Source: https://www.gnu.org/software/grub/manual/grub/grub

A space-separated list of distribution-provided early initrd images to load from /boot. Should not be modified without understanding consequences.

```shell
# GRUB_EARLY_INITRD_LINUX_STOCK="intel-uc.img amd-uc.img"

```

--------------------------------

### GRUB Configuration Entries for Various OS

Source: https://www.gnu.org/software/grub/manual/grub/grub

Defines menu entries in grub.cfg for booting different operating systems, including Linux distributions, Windows, and FreeBSD. It demonstrates the use of modules, search commands, and specific bootloaders.

```grub
menuentry "OS using grub2" {
        insmod xfs
        search --set=root --label OS1 --hint hd0,msdos8
        configfile /boot/grub/grub.cfg
     }

     menuentry "OS using grub2-legacy" {
        insmod ext2
        search --set=root --label OS2 --hint hd0,msdos6
        legacy_configfile /boot/grub/menu.lst
     }

     menuentry "Windows XP" {
        insmod ntfs
        search --set=root --label WINDOWS_XP --hint hd0,msdos1
        ntldr /ntldr
     }

     menuentry "Windows 7" {
        insmod ntfs
        search --set=root --label WINDOWS_7 --hint hd0,msdos2
        ntldr /bootmgr
     }

     menuentry "FreeBSD" {
               insmod zfs
               search --set=root --label freepool --hint hd0,msdos7
               kfreebsd /freebsd@/boot/kernel/kernel
               kfreebsd_module_elf /freebsd@/boot/kernel/opensolaris.ko
               kfreebsd_module_elf /freebsd@/boot/kernel/zfs.ko
               kfreebsd_module /freebsd@/boot/zfs/zpool.cache type=/boot/zfs/zpool.cache
               set kFreeBSD.vfs.root.mountfrom=zfs:freepool/freebsd
               set kFreeBSD.hw.psm.synaptics_support=1
     }

     menuentry "experimental GRUB" {
               search --set=root --label GRUB --hint hd0,msdos5
               multiboot /experimental/grub/i386-pc/core.img
     }

     menuentry "Fedora 16 installer" {
               search --set=root --label GRUB --hint hd0,msdos5
               linux /fedora/vmlinuz lang=en_US keymap=sg resolution=1280x800
               initrd /fedora/initrd.img
     }

     menuentry "Fedora rawhide installer" {
               search --set=root --label GRUB --hint hd0,msdos5
               linux /fedora/vmlinuz repo=ftp://mirror.switch.ch/mirror/fedora/linux/development/rawhide/x86_64 lang=en_US keymap=sg resolution=1280x800
               initrd /fedora/initrd.img
     }

     menuentry "Debian sid installer" {
               search --set=root --label GRUB --hint hd0,msdos5
               linux /debian/dists/sid/main/installer-amd64/current/images/hd-media/vmlinuz
               initrd /debian/dists/sid/main/installer-amd64/current/images/hd-media/initrd.gz
     }
```
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