Using Boot Commands during Installation

Using Boot Commands during Installation

When you boot the PC for installation, either from a boot disk or directly from the first CD-ROM, you get a text screen with the boot: prompt. Typically, you press Enter at that prompt or do nothing and the installation begins shortly. You can, however, type quite a variety of commands at the boot prompt. The commands can provide options to the Linux kernel that takes care of the installation and controls various aspects of the installation such as whether the kernel should probe for hardware or whether to use GUI screens for the installation. Some of these commands can be helpful in bypassing problems that you may encounter during installation.

To use these boot commands, you type the word linux followed by the boot command. For example, to perform text-mode installation and tell the kernel that your PC has 256MB of memory, you’d type the following at the boot prompt:

linux text mem=256M

Consult Table 2-3 for a brief summary of the boot commands.

Insider Insight 

A few of the boot commands do not require you to type linux first. You can simply type text to enter text-mode installation and expert to run the installation in expert mode.

Table 2-3: Linux Boot Commands for Red Hat Linux Installation




Prompts you for other installation methods such as install over the network using NFS, FTP, or HTTP


Works around a bug commonly encountered in the Intel 440GX chipset BIOS and should only be executed with the installation program kernel


Changes how the laptop can be suspended


Disables APM (Advanced Power Management) in case a BIOS has a buggy APM


Causes Red Hat Linux to power off the system (useful for symmetric multiprocessing—SMP—systems that do not shut down by default)


Causes APM to work the way it does in Windows 95 instead of how it works in Windows NT (useful if BIOS crashes when trying to shut down the machine)


Prompts for a driver disk during the installation of Red Hat Linux


Causes installer GUI to appear on the remote system identified by the IP address (make sure that you run the command xhost +hostname on the remote system where hostname is the host where you are running the installer)


Performs the same function as the dd command


Enables you to partition removable media and prompts for a driver disk


Disables DMA (direct memory access) on all IDE devices and can be useful when you are having IDE-related problems


Prompts you for the configuration of older ISA devices—the older IBM-compatible PC architecture) devices


Configures the Ethernet card using DHCP and then runs a kickstart installation by using a kickstart file from an NFS server identified by the bootServer parameters provided by the DHCP server


Runs a kickstart installation by using the kickstart file specified by kickstartfile (see the “Using kickstart Installation” section for the format of the kickstartfile specification)


Forces the installer GUI to run at a lower resolution (640x480)


Prompts you if you want to check the integrity of the CD image (also called ISO image). This is done by computing the MD5 checksum and comparing that with the official Red Hat provided value. It can take a few minutes to check a CD-ROM.


Overrides the amount of memory the kernel detects in the PC (some older machines could detect only 16MB of memory, and on some new machines the video card may use a portion of the main memory). Replace xxx with the number representing the megabytes of memory in your PC.


Enables the built-in kernel deadlock detector that makes use of Non Maskable Interrupt (NMI)


Prevents the kernel from using the Advanced Programmable Interrupt Controller (APIC) chip (use this on motherboards known to have a bad APIC)


Does not load support for FireWire


Disables hyperthreading (a feature available in some SMP systems)


Disables self-diagnosis checks performed on the CPU by using Machine Check Exception (MCE). On some machines these checks are performed too often and need to be disabled.


Does not automatically mount any installed Linux partitions in rescue mode


Does not pass the keyboard and mouse information to stage 2 of the installation program


Ignores any PCMCIA controllers in system


Disables automatic hardware detection and instead prompts the user for information about SCSI and network hardware installed on the PC. You can pass parameters to modules by using this approach.


Disables shell access on virtual console 2 (the one you get by pressing Ctrl-Alt-F2) during installation


Disables the loading of USB support during the installation (may be useful if the installation program hangs early in the process)


Disables the loading of the usbstorage module in the installation program’s loader. It may help with device ordering on SCSI systems.


Changes the way the kernel tries to reboot the PC so that it can reboot even if the kernel hands during system shutdown


Starts the kernel in rescue mode where you get a shell prompt and can try to fix problems


Causes the installer GUI to run in the specified video mode (replace HHH and VVV with standard resolution numbers, such as 640x480, 800x600, 1024x768, and so on)


Turns on serial console support during installation


Skips the Display Data Channel (DDC) probe of monitors (useful if the probing causes problems)


Runs the installation program in text mode


Prompts for a floppy disk containing updates (bug fixes)