Swap & Fall v1.0 serial key or number

You can move your license to a new computer by completing the process described below. However, you’ll need the serial number and product key listed in the license certificate, which was sent to you from registration@bluebeamops.com.

If you’ve lost this information, you can contact License & Registration to request that the license certificate be resent to you. When doing so, be sure to include the serial number, version number, your name, company name, email address and phone number where you can be reached.

Revu 2015 and Microsoft^® ACS retirement

Microsoft^® retired their Access Control Service (ACS), a cloud authentication service that authorized users to access certain web applications and services. The 2015.5 and 2015.6 versions of Revu use ACS when users attempt to register or activate a computer to a license of Revu online. As a result, the online registration process will no longer work with those versions. If you’re on Revu 2015.5 or 2015.6, see Microsoft ACS retirement and Revu authentication for more information, and instructions on transferring your license.

Backing up your Revu Settings

If you would like to keep your settings and stamps from your current computer, please read Backing Up and Restoring Your Bluebeam Revu Settings, Tools Sets, Profiles and Stamps.

Moving the License on Windows^® 10, 8.1 and 7 SP1

1. Go to the Bluebeam Revu Compatibility Chart and confirm that your version of Revu is compatible with the operating system and associated software on your new machine.
2. While the computer is connected to the internet, use the Bluebeam Administrator to unregister the software.
   1. In Windows 10: Click Start > Bluebeam Software > Bluebeam Administrator.
      In Windows 8.1: Click or press Start and type Bluebeam Administrator.
      In Windows 7 SP1: Click Start > All Programs > Bluebeam Software > Bluebeam Administrator.
   2. From the Tools menu, click Unregister.
   3. Click OK.
3. Uninstall Revu from the original computer.
   1. In Windows 10: Right-click Start, then click Apps and Features or Programs and Features at the top.
      In Windows 8.1: Right-click Start, then click Programs and Features at the top.
      In Windows 7 SP1: Click Start > Control Panel, then click Uninstall a program or Programs and Features.
   2. Select Bluebeam Revu and click Uninstall.
   3. Follow the on-screen prompts to continue uninstalling the software.
4. Download and install the software on the new computer. A download link for the software is included in the license certificate, and you can also download the software from our Downloads & Updates page.
   Make sure you download the edition and version of the software listed on your license certificate.
5. During the installation, you’ll be prompted to enter the same serial number and product key you received from Bluebeam.
   Follow the directions to complete the online or manual authorization process to authorize the software on the new computer.

If Revu has already been installed on the new computer, follow the steps listed below to complete the registration process:

1. Open Revu.
2. Click Help > Register.
3. If needed, copy and paste the serial number and product key from the license certificate email, into their corresponding boxes on the Registration dialog box.
4. Click Register and then click Finish.
   If an error message displays during the registration, click here for details about the error and how to resolve it.

Moving the License on Windows XP

Although we’ve provided the instructions listed below, it’s important to know that Microsoft no longer supports Windows XP. With this in mind, we’re unable to provide support for Revu versions that are incompatible with currently supported versions of Windows. Please refer to our compatibility information for further details.

If you’d like to run Bluebeam Revu on a supported version of Windows, you can purchase the current version online from the Bluebeam Store.

1. Go to the Bluebeam Revu Compatibility Chart and confirm that your version of Bluebeam Revu is compatible with the operating system and associated software on your new machine.
2. While the computer is connected to the internet, unregister the software.
   1. Click Start > All Programs > Bluebeam Software > Bluebeam Administrator.
   2. On the Tools menu, click Unregister.
   3. Click OK.
3. Uninstall the Bluebeam software from the original computer.
   1. Click Start and then Control Panel.
   2. Click Add or Remove Programs.
   3. Select Bluebeam Revu in the list.
   4. Click Change/Remove and complete the uninstall.
4. Download and install the software on the new computer.
   1. A download link for the software is included in the license certificate, and you can also download the software from our Downloads & Updates page.
      Make sure you only download and install the edition and version of the software listed on your license certificate.
   2. During the installation, you’ll be prompted to enter the same serial number and product key you received from Bluebeam.
   3. Complete the online or manual authorization process to authorize the software on the new computer.

If Revu has already been installed on the new computer, follow the steps listed below to complete the registration process:

1. Open Revu.
2. Click Help > Register.
3. If needed, copy and paste the serial number and product key from the license certificate email, into their corresponding boxes on the Registration dialog.
4. Click Register and then click Finish.
   If an error message displays during the registration, click here for details about the error and how to resolve it.

GNU GRUB manual

This is the documentation of GNU GRUB, the GRand Unified Bootloader, a flexible and powerful boot loader program for pcs.

This edition documents version 0.97.

This manual is for GNU GRUB (version 0.97, 8 May 2005).

Copyright © 1999,2000,2001,2002,2004,2006 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover Texts being “A GNU Manual,” and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled “GNU Free Documentation License.”

(a) The FSF's Back-Cover Text is: “You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development.”

1 Introduction to GRUB

1.1 Overview

Briefly, a is the first software program that runs when a computer starts. It is responsible for loading and transferring control to an operating system software (such as Linux or GNU Mach). The kernel, in turn, initializes the rest of the operating system (e.g. a GNU system).

GNU GRUB is a very powerful boot loader, which can load a wide variety of free operating systems, as well as proprietary operating systems with chain-loading¹. GRUB is designed to address the complexity of booting a personal computer; both the program and this manual are tightly bound to that computer platform, although porting to other platforms may be addressed in the future.

One of the important features in GRUB is flexibility; GRUB understands filesystems and kernel executable formats, so you can load an arbitrary operating system the way you like, without recording the physical position of your kernel on the disk. Thus you can load the kernel just by specifying its file name and the drive and partition where the kernel resides.

When booting with GRUB, you can use either a command-line interface (see Command-line interface), or a menu interface (see Menu interface). Using the command-line interface, you type the drive specification and file name of the kernel manually. In the menu interface, you just select an OS using the arrow keys. The menu is based on a configuration file which you prepare beforehand (see Configuration). While in the menu, you can switch to the command-line mode, and vice-versa. You can even edit menu entries before using them.

In the following chapters, you will learn how to specify a drive, a partition, and a file name (see Naming convention) to GRUB, how to install GRUB on your drive (see Installation), and how to boot your OSes (see Booting), step by step.

Besides the GRUB boot loader itself, there is a (see Invoking the grub shell) which can be run when you are in your operating system. It emulates the boot loader and can be used for installing the boot loader.

1.2 History of GRUB

GRUB originated in 1995 when Erich Boleyn was trying to boot the GNU Hurd with the University of Utah's Mach 4 microkernel (now known as GNU Mach). Erich and Brian Ford designed the Multiboot Specification (see Multiboot Specification), because they were determined not to add to the large number of mutually-incompatible PC boot methods.

Erich then began modifying the FreeBSD boot loader so that it would understand Multiboot. He soon realized that it would be a lot easier to write his own boot loader from scratch than to keep working on the FreeBSD boot loader, and so GRUB was born.

Erich added many features to GRUB, but other priorities prevented him from keeping up with the demands of its quickly-expanding user base. In 1999, Gordon Matzigkeit and Yoshinori K. Okuji adopted GRUB as an official GNU package, and opened its development by making the latest sources available via anonymous CVS. See Obtaining and Building GRUB, for more information.

1.3 GRUB features

The primary requirement for GRUB is that it be compliant with the , which is described in Multiboot Specification.

The other goals, listed in approximate order of importance, are:

• Basic functions must be straightforward for end-users.
• Rich functionality to support kernel experts and designers.
• Backward compatibility for booting FreeBSD, NetBSD, OpenBSD, and Linux. Proprietary kernels (such as DOS, Windows NT, and OS/2) are supported via a chain-loading function.

Except for specific compatibility modes (chain-loading and the Linux format), all kernels will be started in much the same state as in the Multiboot Specification. Only kernels loaded at 1 megabyte or above are presently supported. Any attempt to load below that boundary will simply result in immediate failure and an error message reporting the problem.

In addition to the requirements above, GRUB has the following features (note that the Multiboot Specification doesn't require all the features that GRUB supports):

Recognize multiple executable formats

Support many of the variants plus . Symbol tables are also loaded.

Support non-Multiboot kernels

Support many of the various free 32-bit kernels that lack Multiboot compliance (primarily FreeBSD, NetBSD, OpenBSD, and Linux). Chain-loading of other boot loaders is also supported.

Load multiples modules

Fully support the Multiboot feature of loading multiple modules.

Load a configuration file

Support a human-readable text configuration file with preset boot commands. You can also load another configuration file dynamically and embed a preset configuration file in a GRUB image file. The list of commands (see Commands) are a superset of those supported on the command-line. An example configuration file is provided in Configuration.

Provide a menu interface

A menu interface listing preset boot commands, with a programmable timeout, is available. There is no fixed limit on the number of boot entries, and the current implementation has space for several hundred.

Have a flexible command-line interface

A fairly flexible command-line interface, accessible from the menu, is available to edit any preset commands, or write a new boot command set from scratch. If no configuration file is present, GRUB drops to the command-line.

The list of commands (see Commands) are a subset of those supported for configuration files. Editing commands closely resembles the Bash command-line (see Bash), with <TAB>-completion of commands, devices, partitions, and files in a directory depending on context.

Support multiple filesystem types

Support multiple filesystem types transparently, plus a useful explicit blocklist notation. The currently supported filesystem types are , , , , , , , and . See Filesystem, for more information.

Support automatic decompression

Can decompress files which were compressed by . This function is both automatic and transparent to the user (i.e. all functions operate upon the uncompressed contents of the specified files). This greatly reduces a file size and loading time, a particularly great benefit for floppies.²

It is conceivable that some kernel modules should be loaded in a compressed state, so a different module-loading command can be specified to avoid uncompressing the modules.

Access data on any installed device

Support reading data from any or all floppies or hard disk(s) recognized by the BIOS, independent of the setting of the root device.

Be independent of drive geometry translations

Unlike many other boot loaders, GRUB makes the particular drive translation irrelevant. A drive installed and running with one translation may be converted to another translation without any adverse effects or changes in GRUB's configuration.

Detect all installed ram

GRUB can generally find all the installed ram on a PC-compatible machine. It uses an advanced BIOS query technique for finding all memory regions. As described on the Multiboot Specification (see Multiboot Specification), not all kernels make use of this information, but GRUB provides it for those who do.

Support Logical Block Address mode

In traditional disk calls (called ), there is a geometry translation problem, that is, the BIOS cannot access over 1024 cylinders, so the accessible space is limited to at least 508 MB and to at most 8GB. GRUB can't universally solve this problem, as there is no standard interface used in all machines. However, several newer machines have the new interface, Logical Block Address () mode. GRUB automatically detects if LBA mode is available and uses it if available. In LBA mode, GRUB can access the entire disk.

Support network booting

GRUB is basically a disk-based boot loader but also has network support. You can load OS images from a network by using the protocol.

Support remote terminals

To support computers with no console, GRUB provides remote terminal support, so that you can control GRUB from a remote host. Only serial terminal support is implemented at the moment.

1.4 The role of a boot loader

The following is a quotation from Gordon Matzigkeit, a GRUB fanatic:

Some people like to acknowledge both the operating system and kernel when they talk about their computers, so they might say they use “GNU/Linux” or “GNU/Hurd”. Other people seem to think that the kernel is the most important part of the system, so they like to call their GNU operating systems “Linux systems.”

I, personally, believe that this is a grave injustice, because the boot loader is the most important software of all. I used to refer to the above systems as either “LILO”³ or “GRUB” systems.

Unfortunately, nobody ever understood what I was talking about; now I just use the word “GNU” as a pseudonym for GRUB.

So, if you ever hear people talking about their alleged “GNU” systems, remember that they are actually paying homage to the best boot loader around... GRUB!

We, the GRUB maintainers, do not (usually) encourage Gordon's level of fanaticism, but it helps to remember that boot loaders deserve recognition. We hope that you enjoy using GNU GRUB as much as we did writing it.

2 Naming convention

The device syntax used in GRUB is a wee bit different from what you may have seen before in your operating system(s), and you need to know it so that you can specify a drive/partition.

Look at the following examples and explanations:

First of all, GRUB requires that the device name be enclosed with `' and `'. The `' part means that it is a floppy disk. The number `' is the drive number, which is counted from zero. This expression means that GRUB will use the whole floppy disk.

Here, `' means it is a hard disk drive. The first integer `' indicates the drive number, that is, the first hard disk, while the second integer, `', indicates the partition number (or the pc slice number in the BSD terminology). Once again, please note that the partition numbers are counted from zero, not from one. This expression means the second partition of the first hard disk drive. In this case, GRUB uses one partition of the disk, instead of the whole disk.

This specifies the first of the first hard disk drive. Note that the partition numbers for extended partitions are counted from `', regardless of the actual number of primary partitions on your hard disk.

This means the BSD `' partition of the second hard disk. If you need to specify which pc slice number should be used, use something like this: `'. If the pc slice number is omitted, GRUB searches for the first pc slice which has a BSD `' partition.

Of course, to actually access the disks or partitions with GRUB, you need to use the device specification in a command, like `' or `'. To help you find out which number specifies a partition you want, the GRUB command-line (see Command-line interface) options have argument completion. This means that, for example, you only need to type

followed by a <TAB>, and GRUB will display the list of drives, partitions, or file names. So it should be quite easy to determine the name of your target partition, even with minimal knowledge of the syntax.

Note that GRUB does not distinguish IDE from SCSI - it simply counts the drive numbers from zero, regardless of their type. Normally, any IDE drive number is less than any SCSI drive number, although that is not true if you change the boot sequence by swapping IDE and SCSI drives in your BIOS.

Now the question is, how to specify a file? Again, consider an example:

This specifies the file named `', found on the first partition of the first hard disk drive. Note that the argument completion works with file names, too.

That was easy, admit it. Now read the next chapter, to find out how to actually install GRUB on your drive.

3 Installation

In order to install GRUB as your boot loader, you need to first install the GRUB system and utilities under your UNIX-like operating system (see Obtaining and Building GRUB). You can do this either from the source tarball, or as a package for your OS.

After you have done that, you need to install the boot loader on a drive (floppy or hard disk). There are two ways of doing that - either using the utility (see Invoking grub-install) on a UNIX-like OS, or by running GRUB itself from a floppy. These are quite similar, however the utility might probe a wrong BIOS drive, so you should be careful.

Also, if you install GRUB on a UNIX-like OS, please make sure that you have an emergency boot disk ready, so that you can rescue your computer if, by any chance, your hard drive becomes unusable (unbootable).

GRUB comes with boot images, which are normally put in the directory . If you do not use grub-install, then you need to copy the files , , and to the directory , and run the (see Invoking grub-set-default) if you intend to use `' (see default) in your configuration file. Hereafter, the directory where GRUB images are initially placed (normally ) will be called the , and the directory where the boot loader needs to find them (usually ) will be called the .

3.1 Creating a GRUB boot floppy

To create a GRUB boot floppy, you need to take the files and from the image directory, and write them to the first and the second block of the floppy disk, respectively.

Caution: This procedure will destroy any data currently stored on the floppy.

On a UNIX-like operating system, that is done with the following commands:

The device file name may be different. Consult the manual for your OS.

3.2 Installing GRUB natively

Caution: Installing GRUB's stage1 in this manner will erase the normal boot-sector used by an OS.

GRUB can currently boot GNU Mach, Linux, FreeBSD, NetBSD, and OpenBSD directly, so using it on a boot sector (the first sector of a partition) should be okay. But generally, it would be a good idea to back up the first sector of the partition on which you are installing GRUB's stage1. This isn't as important if you are installing GRUB on the first sector of a hard disk, since it's easy to reinitialize it (e.g. by running `' from DOS).

If you decide to install GRUB in the native environment, which is definitely desirable, you'll need to create a GRUB boot disk, and reboot your computer with it. Otherwise, see Installing GRUB using grub-install.

Once started, GRUB will show the command-line interface (see Command-line interface). First, set the GRUB's ⁴ to the partition containing the boot directory, like this:

If you are not sure which partition actually holds this directory, use the command (see find), like this:

This will search for the file name and show the devices which contain the file.

Once you've set the root device correctly, run the command (see setup):

This command will install the GRUB boot loader on the Master Boot Record (MBR) of the first drive. If you want to put GRUB into the boot sector of a partition instead of putting it in the MBR, specify the partition into which you want to install GRUB:

If you install GRUB into a partition or a drive other than the first one, you must chain-load GRUB from another boot loader. Refer to the manual for the boot loader to know how to chain-load GRUB.

After using the setup command, you will boot into GRUB without the GRUB floppy. See the chapter Booting to find out how to boot your operating systems from GRUB.

3.3 Installing GRUB using grub-install

Caution: This procedure is definitely less safe, because there are several ways in which your computer can become unbootable. For example, most operating systems don't tell GRUB how to map BIOS drives to OS devices correctly—GRUB merely the mapping. This will succeed in most cases, but not always. Therefore, GRUB provides you with a map file called the , which you must fix if it is wrong. See Device map, for more details.

If you still do want to install GRUB under a UNIX-like OS (such as gnu), invoke the program (see Invoking grub-install) as the superuser ().

The usage is basically very simple. You only need to specify one argument to the program, namely, where to install the boot loader. The argument can be either a device file (like `') or a partition specified in GRUB's notation. For example, under Linux the following will install GRUB into the MBR of the first IDE disk:

Likewise, under GNU/Hurd, this has the same effect:

If it is the first BIOS drive, this is the same as well:

Or you can omit the parentheses:

But all the above examples assume that GRUB should use images under the root directory. If you want GRUB to use images under a directory other than the root directory, you need to specify the option . The typical usage is that you create a GRUB boot floppy with a filesystem. Here is an example:

Another example is when you have a separate boot partition which is mounted at . Since GRUB is a boot loader, it doesn't know anything about mountpoints at all. Thus, you need to run like this:

By the way, as noted above, it is quite difficult to guess BIOS drives correctly under a UNIX-like OS. Thus, will prompt you to check if it could really guess the correct mappings, after the installation. The format is defined in Device map. Please be quite careful. If the output is wrong, it is unlikely that your computer will be able to boot with no problem.

Note that is actually just a shell script and the real task is done by the grub shell (see Invoking the grub shell). Therefore, you may run directly to install GRUB, without using . Don't do that, however, unless you are very familiar with the internals of GRUB. Installing a boot loader on a running OS may be extremely dangerous.

3.4 Making a GRUB bootable CD-ROM

GRUB supports the in the El Torito specification⁵. This means that you can use the whole CD-ROM from GRUB and you don't have to make a floppy or hard disk image file, which can cause compatibility problems.

For booting from a CD-ROM, GRUB uses a special Stage 2 called . The only GRUB files you need to have in your bootable CD-ROM are this and optionally a config file . You don't need to use or , because El Torito is quite different from the standard boot process.

Here is an example of procedures to make a bootable CD-ROM image. First, make a top directory for the bootable image, say, `':

Make a directory for GRUB:

Copy the file :

If desired, make the config file under (see Configuration), and copy any files and directories for the disc to the directory .

Finally, make a ISO9660 image file like this:

This produces a file named , which then can be burned into a CD (or a DVD). has already set up the disc to boot from the file, so there is no need to setup GRUB on the disc. (Note that the bit is required for compatibility with the BIOS on many older machines.)

You can use the device `' to access a CD-ROM in your config file. This is not required; GRUB automatically sets the root device to `' when booted from a CD-ROM. It is only necessary to refer to `' if you want to access other drives as well.

4 Booting

GRUB can load Multiboot-compliant kernels in a consistent way, but for some free operating systems you need to use some OS-specific magic.

4.1 How to boot operating systems

GRUB has two distinct boot methods. One of the two is to load an operating system directly, and the other is to chain-load another boot loader which then will load an operating system actually. Generally speaking, the former is more desirable, because you don't need to install or maintain other boot loaders and GRUB is flexible enough to load an operating system from an arbitrary disk/partition. However, the latter is sometimes required, since GRUB doesn't support all the existing operating systems natively.

4.1.1 How to boot an OS directly with GRUB

Multiboot (see Multiboot Specification) is the native format supported by GRUB. For the sake of convenience, there is also support for Linux, FreeBSD, NetBSD and OpenBSD. If you want to boot other operating systems, you will have to chain-load them (see Chain-loading).

Generally, GRUB can boot any Multiboot-compliant OS in the following steps:

1. Set GRUB's root device to the drive where the OS images are stored with the command (see root).
2. Load the kernel image with the command (see kernel).
3. If you need modules, load them with the command (see module) or (see modulenounzip).
4. Run the command (see boot).

Linux, FreeBSD, NetBSD and OpenBSD can be booted in a similar manner. You load a kernel image with the command and then run the command . If the kernel requires some parameters, just append the parameters to , after the file name of the kernel. Also, please refer to OS-specific notes, for information on your OS-specific issues.

4.1.2 Load another boot loader to boot unsupported operating systems

If you want to boot an unsupported operating system (e.g. Windows 95), chain-load a boot loader for the operating system. Normally, the boot loader is embedded in the of the partition on which the operating system is installed.

1. Set GRUB's root device to the partition by the command (see rootnoverify): grub>
2. Set the flag in the partition using the command ⁶ (see makeactive): grub>
3. Load the boot loader with the command (see chainloader): grub>

   `' indicates that GRUB should read one sector from the start of the partition. The complete description about this syntax can be found in Block list syntax.

4. Run the command (see boot).

However, DOS and Windows have some deficiencies, so you might have to use more complicated instructions. See DOS/Windows, for more information.

4.2 Some caveats on OS-specific issues

Here, we describe some caveats on several operating systems.

4.2.1 GNU/Hurd

Since GNU/Hurd is Multiboot-compliant, it is easy to boot it; there is nothing special about it. But do not forget that you have to specify a root partition to the kernel.

1. Set GRUB's root device to the same drive as GNU/Hurd's. Probably the command or similar can help you (see find).
2. Load the kernel and the module, like this: grub> grub>
3. Run the command (see boot).

4.2.2 GNU/Linux

It is relatively easy to boot GNU/Linux from GRUB, because it somewhat resembles to boot a Multiboot-compliant OS.

1. Set GRUB's root device to the same drive as GNU/Linux's. Probably the command or similar can help you (see find).
2. Load the kernel: grub>

   If you need to specify some kernel parameters, just append them to the command. For example, to set to `', do this:

   grub>

   See the documentation in the Linux source tree for complete information on the available options.

3. If you use an initrd, execute the command (see initrd) after : grub>
4. Finally, run the command (see boot).

Caution: If you use an initrd and specify the `' option to the kernel to let it use less than actual memory size, you will also have to specify the same memory size to GRUB. To let GRUB know the size, run the command before loading the kernel. See uppermem, for more information.

4.2.3 FreeBSD

GRUB can load the kernel directly, either in ELF or a.out format. But this is not recommended, since FreeBSD's bootstrap interface sometimes changes heavily, so GRUB can't guarantee to pass kernel parameters correctly.

Thus, we'd recommend loading the very flexible loader instead. See this example:

4.2.4 NetBSD

GRUB can load NetBSD a.out and ELF directly, follow these steps:

1. Set GRUB's root device with (see root).
2. Load the kernel with (see kernel). You should append the ugly option , if you want to load an ELF kernel, like this: grub>
3. Run (see boot).

For now, however, GRUB doesn't allow you to pass kernel parameters, so it may be better to chain-load it instead. For more information, please see Chain-loading.

4.2.5 OpenBSD

The booting instruction is exactly the same as for NetBSD (see NetBSD).

4.2.6 DOS/Windows

GRUB cannot boot DOS or Windows directly, so you must chain-load them (see Chain-loading). However, their boot loaders have some critical deficiencies, so it may not work to just chain-load them. To overcome the problems, GRUB provides you with two helper functions.

If you have installed DOS (or Windows) on a non-first hard disk, you have to use the disk swapping technique, because that OS cannot boot from any disks but the first one. The workaround used in GRUB is the command (see map), like this:

This performs a swap between your first and second hard drive.

Caution: This is effective only if DOS (or Windows) uses BIOS to access the swapped disks. If that OS uses a special driver for the disks, this probably won't work.

Another problem arises if you installed more than one set of DOS/Windows onto one disk, because they could be confused if there are more than one primary partitions for DOS/Windows. Certainly you should avoid doing this, but there is a solution if you do want to do so. Use the partition hiding/unhiding technique.

If GRUB s a DOS (or Windows) partition (see hide), DOS (or Windows) will ignore the partition. If GRUB s a DOS (or Windows) partition (see unhide), DOS (or Windows) will detect the partition. Thus, if you have installed DOS (or Windows) on the first and the second partition of the first hard disk, and you want to boot the copy on the first partition, do the following:

4.2.7 SCO UnixWare

It is known that the signature in the boot loader for SCO UnixWare is wrong, so you will have to specify the option to (see chainloader), like this:

4.2.8 QNX

QNX seems to use a bigger boot loader, so you need to boot it up, like this:

4.3 How to make your system robust

When you test a new kernel or a new OS, it is important to make sure that your computer can boot even if the new system is unbootable. This is crucial especially if you maintain servers or remote systems. To accomplish this goal, you need to set up two things:

1. You must maintain a system which is always bootable. For instance, if you test a new kernel, you need to keep a working kernel in a different place. And, it would sometimes be very nice to even have a complete copy of a working system in a different partition or disk.
2. You must direct GRUB to boot a working system when the new system fails. This is possible with the system in GRUB.

The former requirement is very specific to each OS, so this documentation does not cover that topic. It is better to consult some backup tools.

So let's see the GRUB part. There are two possibilities: one of them is quite simple but not very robust, and the other is a bit complex to set up but probably the best solution to make sure that your system can start as long as GRUB itself is bootable.

4.3.1 Booting once-only

You can teach GRUB to boot an entry only at next boot time. Suppose that your have an old kernel and a new kernel . You know that can boot your system correctly, and you want to test .

To ensure that your system will go back to the old kernel even if the new kernel fails (e.g. it panics), you can specify that GRUB should try the new kernel only once and boot the old kernel after that.

First, modify your configuration file. Here is an example:

Note that this configuration file uses `' (see default) at the head and `' (see savedefault) in the entry for the new kernel. This means that GRUB boots a saved entry by default, and booting the entry for the new kernel saves `' as the saved entry.

With this configuration file, after all, GRUB always tries to boot the old kernel after it booted the new one, because `' is the entry of .

The next step is to tell GRUB to boot the new kernel at next boot time. For this, execute (see Invoking grub-set-default):

This command sets the saved entry to `', that is, to the new kernel.

This method is useful, but still not very robust, because GRUB stops booting, if there is any error in the boot entry, such that the new kernel has an invalid executable format. Thus, it it even better to use the mechanism of GRUB. Look at next subsection for this feature.

4.3.2 Booting fallback systems

GRUB supports a fallback mechanism of booting one or more other entries if a default boot entry fails. You can specify multiple fallback entries if you wish.

Suppose that you have three systems, `', `' and `'. `' is a system which you want to boot by default. `' is a backup system which is supposed to boot safely. `' is another backup system which is used in case where `' is broken.

Then you may want GRUB to boot the first system which is bootable among `', `' and `'. A configuration file can be written in this way:

Note that `' (see default), `' and `' are used. GRUB will boot a saved entry by default and save a fallback entry as next boot entry with this configuration.

When GRUB tries to boot `', GRUB saves `' as next boot entry, because the command specifies that `' is the first fallback entry. The entry `' is `', so GRUB will try to boot `' at next boot time.

Likewise, when GRUB tries to boot `', GRUB saves `' as next boot entry, because specifies `' as next fallback entry. This makes sure that GRUB will boot `' after booting `'.

It is noteworthy that GRUB uses fallback entries both when GRUB itself fails in booting an entry and when `' or `' fails in starting up your system. So this solution ensures that your system is started even if GRUB cannot find your kernel or if your kernel panics.

However, you need to run (see Invoking grub-set-default) when `' starts correctly or you fix `' after it crashes, since GRUB always sets next boot entry to a fallback entry. You should run this command in a startup script such as to boot `' by default:

where `' is the number of the boot entry for the system `'.

If you want to see what is current default entry, you can look at the file (or in some systems). Because this file is plain-text, you can just this file. But it is strongly recommended not to modify this file directly, because GRUB may fail in saving a default entry in this file, if you change this file in an unintended manner. Therefore, you should use when you need to change the default entry.

5 Configuration

You've probably noticed that you need to type several commands to boot your OS. There's a solution to that - GRUB provides a menu interface (see Menu interface) from which you can select an item (using arrow keys) that will do everything to boot an OS.

To enable the menu, you need a configuration file, under the boot directory. We'll analyze an example file.

The file first contains some general settings, the menu interface related options. You can put these commands (see Menu-specific commands) before any of the items (starting with (see title)).

As you may have guessed, these lines are comments. Lines starting with a hash character (`'), and blank lines, are ignored by GRUB.

The first entry (here, counting starts with number zero, not one!) will be the default choice.

As the comment says, GRUB will boot automatically in 30 seconds, unless interrupted with a keypress.

If, for any reason, the default entry doesn't work, fall back to the second one (this is rarely used, for obvious reasons).

Note that the complete descriptions of these commands, which are menu interface specific, can be found in Menu-specific commands. Other descriptions can be found in Commands.

Now, on to the actual OS definitions. You will see that each entry begins with a special command, (see title), and the action is described after it. Note that there is no command (see boot) at the end of each item. That is because GRUB automatically executes if it loads other commands successfully.

The argument for the command is used to display a short title/description of the entry in the menu. Since displays the argument as is, you can write basically anything there.

This boots GNU/Hurd from the first hard disk.

This boots GNU/Linux, but from the second hard disk.

This boots Mach with a kernel on a floppy, but the root filesystem at hd0s3. It also contains a line (see pause), which will cause GRUB to display a prompt and delay, before actually executing the rest of the commands and booting.

This item will boot FreeBSD kernel loaded from the `' partition of the third pc slice of the first hard disk.

This will boot OS/2, using a chain-loader (see Chain-loading).

The same as the above, but for Windows.

This will just (re)install GRUB onto the hard disk.

In the last entry, the command is used (see color), to change the menu colors (try it!). This command is somewhat special, because it can be used both in the command-line and in the menu. GRUB has several such commands, see General commands.

We hope that you now understand how to use the basic features of GRUB. To learn more about GRUB, see the following chapters.

6 Downloading OS images from a network

Although GRUB is a disk-based boot loader, it does provide network support. To use the network support, you need to enable at least one network driver in the GRUB build process. For more information please see in the source distribution.

6.1 How to set up your network

GRUB requires a file server and optionally a server that will assign an IP address to the machine on which GRUB is running. For the former, only TFTP is supported at the moment. The latter is either BOOTP, DHCP or a RARP server⁷. It is not necessary to run both the servers on one computer. How to configure these servers is beyond the scope of this document, so please refer to the manuals specific to those protocols/servers.

If you decided to use a server to assign an IP address, set up the server and run (see bootp), (see dhcp) or (see rarp) for BOOTP, DHCP or RARP, respectively. Each command will show an assigned IP address, a netmask, an IP address for your TFTP server and a gateway. If any of the addresses is wrong or it causes an error, probably the configuration of your servers isn't set up properly.

Otherwise, run , like this:

You can also use in conjuction with , or (e.g. to reassign the server address manually). See ifconfig, for more details.

Finally, download your OS images from your network. The network can be accessed using the network drive `'. Everything else is very similar to the normal instructions (see Booting).

Here is an example:

6.2 Booting from a network

It is sometimes very useful to boot from a network, especially when you use a machine which has no local disk. In this case, you need to obtain a kind of Net Boot rom, such as a PXE rom or a free software package like Etherboot. Such a Boot rom first boots the machine, sets up the network card installed into the machine, and downloads a second stage boot image from the network. Then, the second image will try to boot an operating system actually from the network.

GRUB provides two second stage images, and (see Images). These images are the same as the normal Stage 2, except that they set up a network automatically, and try to load a configuration file from the network, if specified. The usage is very simple: If the machine has a PXE rom, use . If the machine has an NBI loader such as Etherboot, use . There is no difference between them except their formats. Since the way to load a second stage image you want to use should be described in the manual on your Net Boot rom, please refer to the manual, for more information.

However, there is one thing specific to GRUB. Namely, how to specify a configuration file in a BOOTP/DHCP server. For now, GRUB uses the tag `', to get the name of a configuration file. The following is an example with a BOOTP configuration:

Note that you should specify the drive name in the name of the configuration file. This is because you might change the root drive before downloading the configuration from the TFTP server when the preset menu feature is used (see Preset Menu).

See the manual of your BOOTP/DHCP server for more information. The exact syntax should differ a little from the example.

7 Using GRUB via a serial line

This chapter describes how to use the serial terminal support in GRUB.

If you have many computers or computers with no display/keyboard, it could be very useful to control the computers through serial communications. To connect one computer with another via a serial line, you need to prepare a null-modem (cross) serial cable, and you may need to have multiport serial boards, if your computer doesn't have extra serial ports. In addition, a terminal emulator is also required, such as minicom. Refer to a manual of your operating system, for more information.

As for GRUB, the instruction to set up a serial terminal is quite simple. First of all, make sure that you haven't specified the option to the configure script when you built your GRUB images. If you get them in binary form, probably they have serial terminal support already.

Then, initialize your serial terminal after GRUB starts up. Here is an example:

The command initializes the serial unit 0 with the speed 9600bps. The serial unit 0 is usually called `', so, if you want to use COM2, you must specify `' instead. This command accepts many other options, so please refer to serial, for more details.

The command (see terminal) chooses which type of terminal you want to use. In the case above, the terminal will be a serial terminal, but you can also pass to the command, as `'. In this case, a terminal in which you press any key will be selected as a GRUB terminal.

However, note that GRUB assumes that your terminal emulator is compatible with VT100 by default. This is true for most terminal emulators nowadays, but you should pass the option to the command if your terminal emulator is not VT100-compatible or implements few VT100 escape sequences. If you specify this option then GRUB provides you with an alternative menu interface, because the normal menu requires several fancy features of your terminal.

8 Embedding a configuration file into GRUB

GRUB supports a which is to be always loaded before starting. The preset menu feature is useful, for example, when your computer has no console but a serial cable. In this case, it is critical to set up the serial terminal as soon as possible, since you cannot see any message until the serial terminal begins to work. So it is good to run the commands (see serial) and (see terminal) before anything else at the start-up time.

How the preset menu works is slightly complicated:

1. GRUB checks if the preset menu feature is used, and loads the preset menu, if available. This includes running commands and reading boot entries, like an ordinary configuration file.
2. GRUB checks if the configuration file is available. Note that this check is performed regardless of the existence of the preset menu. The configuration file is loaded even if the preset menu was loaded.
3. If the preset menu includes any boot entries, they are cleared when the configuration file is loaded. It doesn't matter whether the configuration file has any entries or no entry. The boot entries in the preset menu are used only when GRUB fails in loading the configuration file.

To enable the preset menu feature, you must rebuild GRUB specifying a file to the configure script with the option . The file has the same semantics as normal configuration files (see Configuration).

Another point you should take care is that the diskless support (see Diskless) diverts the preset menu. Diskless images embed a preset menu to execute the command (see bootp) automatically, unless you specify your own preset menu to the configure script. This means that you must put commands to initialize a network in the preset menu yourself, because diskless images don't set it up implicitly, when you use the preset menu explicitly.

Therefore, a typical preset menu used with diskless support would be like this:

9 Protecting your computer from cracking

You may be interested in how to prevent ordinary users from doing whatever they like, if you share your computer with other people. So this chapter describes how to improve the security of GRUB.

One thing which could be a security hole is that the user can do too many things with GRUB, because GRUB allows one to modify its configuration and run arbitrary commands at run-time. For example, the user can even read in the command-line interface by the command (see cat). So it is necessary to disable all the interactive operations.

Thus, GRUB provides a feature, so that only administrators can start the interactive operations (i.e. editing menu entries and entering the command-line interface). To use this feature, you need to run the command in your configuration file (see password), like this:

If this is specified, GRUB disallows any interactive control, until you press the key <p> and enter a correct password. The option tells GRUB that `' is in MD5 format. If it is omitted, GRUB assumes the `' is in clear text.

You can encrypt your password with the command (see md5crypt). For example, run the grub shell (see Invoking the grub shell), and enter your password:

Then, cut and paste the encrypted password to your configuration file.

Also, you can specify an optional argument to . See this example:

In this case, GRUB will load as a configuration file when you enter the valid password.

Another thing which may be dangerous is that any user can choose any menu entry. Usually, this wouldn't be problematic, but you might want to permit only administrators to run some of your menu entries, such as an entry for booting an insecure OS like DOS.

GRUB provides the command (see lock). This command always fails until you enter the valid password, so you can use it, like this:

You should insert right after , because any user can execute commands in an entry until GRUB encounters .

You can also use the command instead of . In this case the boot process will ask for the password and stop if it was entered incorrectly. Since the takes its own argument this is useful if you want different passwords for different entries.

10 GRUB image files

GRUB consists of several images: two essential stages, optional stages called , one image for bootable CD-ROM, and two network boot images. Here is a short overview of them. See Internals, for more details.

This is an essential image used for booting up GRUB. Usually, this is embedded in an MBR or the boot sector of a partition. Because a PC boot sector is 512 bytes, the size of this image is exactly 512 bytes.

All must do is to load Stage 2 or Stage 1.5 from a local disk. Because of the size restriction, encodes the location of Stage 2 (or Stage 1.5) in a block list format, so it never understand any filesystem structure.

This is the core image of GRUB. It does everything but booting up itself. Usually, this is put in a filesystem, but that is not required.

These are called , because they serve as a bridge between and , that is to say, Stage 1.5 is loaded by Stage 1 and Stage 1.5 loads Stage 2. The difference between and is that the former doesn't understand any filesystem while the latter understands one filesystem (e.g. understands ext2fs). So you can move the Stage 2 image to another location safely, even after GRUB has been installed.

While Stage 2 cannot generally be embedded in a fixed area as the size is so large, Stage 1.5 can be installed into the area right after an MBR, or the boot loader area of a ReiserFS or a FFS.

This is a boot image for CD-ROMs using the in El Torito specification. This is identical to Stage 2, except that this boots up without Stage 1 and sets up a special drive `'.

This is a network boot image for the Network Image Proposal used by some network boot loaders, such as Etherboot. This is mostly the same as Stage 2, but it also sets up a network and loads a configuration file from the network.

This is another network boot image for the Preboot Execution Environment used by several Netboot ROMs. This is identical to , except for the format.

11 Filesystem syntax and semantics

GRUB uses a special syntax for specifying disk drives which can be accessed by BIOS. Because of BIOS limitations, GRUB cannot distinguish between IDE, ESDI, SCSI, or others. You must know yourself which BIOS device is equivalent to which OS device. Normally, that will be clear if you see the files in a device or use the command (see find).

11.1 How to specify devices

The device syntax is like this:

`' means the parameter is optional. should be either `' or `' followed by a digit, like `'. But you can also set to a hexadecimal or a decimal number which is a BIOS drive number, so the following are equivalent:

represents the partition number of , starting from zero for primary partitions and from four for extended partitions, and represents the BSD disklabel subpartition, such as `' or `'.

A shortcut for specifying BSD subpartitions is , in this case, GRUB searches for the first PC partition containing a BSD disklabel, then finds the subpartition . Here is an example:

The syntax `' represents using the entire disk (or the MBR when installing GRUB), while the syntax `' represents using the first partition of the disk (or the boot sector of the partition when installing GRUB).

If you enabled the network support, the special drive, `', is also available. Before using the network drive, you must initialize the network. See Network, for more information.

If you boot GRUB from a CD-ROM, `' is available. See Making a GRUB bootable CD-ROM, for details.

11.2 How to specify files

There are two ways to specify files, by and by .

An absolute file name resembles a Unix absolute file name, using `' for the directory separator (not `' as in DOS). One example is `'. This means the file in the first partition of the first hard disk. If you omit the device name in an absolute file name, GRUB uses GRUB's implicitly. So if you set the root device to, say, `' by the command (see root), then is the same as .

11.3 How to specify block lists

A block list is used for specifying a file that doesn't appear in the filesystem, like a chainloader. The syntax is . Here is an example:

This represents that GRUB should read blocks 0 through 99, block 200, and blocks 300 through 599. If you omit an offset, then GRUB assumes the offset is zero.

Like the file name syntax (see File name syntax), if a blocklist does not contain a device name, then GRUB uses GRUB's . So is the same as when the root device is `'.

12 GRUB's user interface

GRUB has both a simple menu interface for choosing preset entries from a configuration file, and a highly flexible command-line for performing any desired combination of boot commands.

GRUB looks for its configuration file as soon as it is loaded. If one is found, then the full menu interface is activated using whatever entries were found in the file. If you choose the menu option, or if the configuration file was not found, then GRUB drops to the command-line interface.

12.1 The flexible command-line interface

The command-line interface provides a prompt and after it an editable text area much like a command-line in Unix or DOS. Each command is immediately executed after it is entered⁸. The commands (see Command-line and menu entry commands) are a subset of those available in the configuration file, used with exactly the same syntax.

Cursor movement and editing of the text on the line can be done via a subset of the functions available in the Bash shell:

<C-f>

<PC right key>

Move forward one character.

<C-b>

<PC left key>

Move back one character.

<C-a>

<HOME>

Move to the start of the line.

<C-e>

<END>

Move the the end of the line.

<C-d>

<DEL>

Delete the character underneath the cursor.

<C-h>

The deployment manifest is a YAML file that defines the components and properties of the deployment. When an operator initiates a new deployment using the CLI, the Director receives a manifest and creates or updates a deployment with matching name.

Assuming that you are using cloud config, your deployment manifest is expected to have:

Deployment Identification¶

name [String, required]: The name of the deployment. A single Director can manage multiple deployments and distinguishes them by name.

director_uuid [String, required]: Not required by CLI v2. This string must match the UUID of the currently targeted Director for the CLI to allow any operations on the deployment. Use to display the UUID of the currently targeted Director.

Example:

Features Block¶

features [Hash, options]: Specifies Director features that should be used within this deployment.

• converge_variables [Boolean, optional]: Enable variables to be regenerated by the backend config server (e.g. CredHub) when the variable change. Default . Available in bosh-release 267+.
• randomize_az_placement [Boolean, optional]: Randomizes AZs for left over instances that cannot be distributed equally between AZs. For example, given an instance group with 5 instances and only 3 AZs, 1 remaining instance will be placed in randomly chosen AZ out of specified 3 AZs. Available in bosh-release 264+.
• use_dns_addresses [Boolean, optional]: Enables or disables returning of DNS addresses in links. Defaults to global Director configuration.
• use_tmpfs_config [Boolean, optional]: Mounts all directories which contain rendered job templates on tmpfs by default on every instance group. Default .
• use_short_dns_addresses [Boolean, optional]: Uses a shorter DNS query format to reduce length of DNS name, for use in certificate common names. Default: . See DNS and variables integration for more.

Example:

Releases Block¶

releases [Array, required]: The name and version of each release in the deployment.

• name [String, required]: Name of a release used in the deployment.
• version [String, required]: The version of the release to use. Version can be .
• url [String, optional]: URL of a release to download. Works with CLI v2. Example: .
• sha1 [String, optional]: SHA1 of asset referenced via URL. Works with CLI v2. Example: