Understanding The Boot Environment Variable; Understanding The Config_File Environment Variable - Cisco WS-C4003 - Catalyst 4000 Chassis Switch Software Configuration Manual

Chapter 28 Modifying the Switch Boot Configuration
The other bits in the configuration register function as follows when set:
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Understanding the BOOT Environment Variable

The BOOT environment variable specifies a list of image files on various devices from which the switch
can boot at startup.
You can add several images to the BOOT environment variable to provide a fail-safe boot configuration.
If the first file fails to boot the switch, subsequent images specified in the BOOT variable are tried until
the switch boots or there are no additional images to attempt to boot. If there is no valid image to boot,
the system enters ROM-monitor mode where you can manually specify an image to boot.
The system stores and executes images in the order in which you added them to the BOOT variable. If
you want to change the order in which images are tried at startup, you can either prepend and clear
images from the BOOT variable to attain the desired order or you can clear the entire BOOT environment
variable and then redefine the list in the desired order.

Understanding the CONFIG_FILE Environment Variable

In software release 5.2 and later, you can use the CONFIG_FILE environment variable to specify a list
of configuration files on various devices to use to configure the switch at startup. You can specify one
of the following functions:
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Note Remember that the CONFIG_FILE variable can be altered or its recurrence properties changed by
commands in the configuration files used to configure the switch at startup.
For information on specifying recurrence or nonrecurrence, see the
Recurrence" section on page
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Bit 5 (0x0020): Enables CONFIG_FILE recurrence.
Bit 6 (0x0040): Causes system software to clear NVRAM contents.
Bit 7 (0x0080): Enables OEM bit (not used).
Bit 8 (0x0100): Disables break.
Bit 9 (0x0200): Uses secondary bootstrap (not used by the ROM monitor).
Bit 10 (0x0400): Provides IP broadcast with all zeros (not used).
Bits 11/12 (0x0800/0x1000): These bits are always set to 0/0 (9600 baud).
Bit 13 (0x2000): Boots default Flash software if network boot fails (not used).
Bit 14 (0x4000): IP broadcasts do not have network numbers (not used).
Bit 15 (0x8000): Enables diagnostic messages and ignores NVRAM contents (not used).
Nonrecurring—When you add a list of configuration files to the CONFIG_FILE environment
variable, the next time the switch is restarted, the system erases the configuration in NVRAM and
uses the specified files to configure the switch. The CONFIG_FILE variable is cleared before the
switch is configured. Nonrecurring is the default setting.
Recurring—When you add a list of configuration files to the CONFIG_FILE environment variable,
the list is stored indefinitely in NVRAM. Each time the switch is restarted, the system erases the
configuration in NVRAM and configures the switch using the configuration files specified. The
CONFIG_FILE variable is not cleared.
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Software Configuration Guide—Catalyst 4000 Family, Catalyst 2948G, Catalyst 2980G, Releases 6.3 and 6.4
Understanding How the Switch Boot Configuration Works
"Setting CONFIG_FILE
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