Controlling Environment Variables - Cisco Catalyst 2960 Software Configuration Manual

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Assigning the Switch IP Address and Default Gateway

Controlling Environment Variables

With a normally operating switch, you enter the boot loader mode only through a switch console

connection configured for 9600 b/s. Unplug the switch power cord, and press the switch Mode button

while reconnecting the power cord. You can release the Mode button a second or two after the LED

above port 1 turns off. Then the boot loader switch: prompt appears.

The switch boot loader software provides support for nonvolatile environment variables, which can be

used to control how the boot loader, or any other software running on the system, behaves. Boot loader

environment variables are similar to environment variables that can be set on UNIX or DOS systems.

Environment variables that have values are stored in flash memory outside of the flash file system.

Each line in these files contains an environment variable name and an equal sign followed by the value

of the variable. A variable has no value if it is not listed in this file; it has a value if it is listed in the file

even if the value is a null string. A variable that is set to a null string (for example, " ") is a variable with

a value. Many environment variables are predefined and have default values.

Environment variables store two kinds of data:

You can change the settings of the environment variables by accessing the boot loader or by using Cisco

IOS commands. Under normal circumstances, it is not necessary to alter the setting of the environment

For complete syntax and usage information for the boot loader commands and environment variables,

see the command reference for this release.

Data that controls code, which does not read the Cisco IOS configuration file. For example, the name

of a boot loader helper file, which extends or patches the functionality of the boot loader can be

stored as an environment variable.

Data that controls code, which is responsible for reading the Cisco IOS configuration file. For

example, the name of the Cisco IOS configuration file can be stored as an environment variable.

Catalyst 2960 and 2960-S Switches Software Configuration Guide, Release 15.0(1)SE

Modifying the Startup Configuration

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Catalyst 2960-s