Modifying the Configuration File The Cisco IOS software accepts one configuration command per line. You can enter as many configuration commands as you want. You can add comments to a configuration file describing the commands you have entered. Precede a comment with an exclamation point (!). Because comments are not stored in NVRAM or in the active copy of the configuration file, comments do not appear when you list the active configuration with the show running-config or more system:running-config EXEC commands. Comments do not display when you list the startup configuration with the show startup-config or more nvram:startup-config EXEC mode commands.
Comments are stripped out of the configuration file when it is loaded onto the device. However, you can list the comments in configuration files stored on a File Transfer Protocol (FTP), Remote Copy Protocol (RCP), or Trivial File Transfer Protocol (TFTP) server. When you configure the software using the CLI, the software executes the commands as you enter them. To configure the software using the CLI, use the following commands in privileged EXEC mode: Procedure Managing Configuration Files Modifying the Configuration File Command or Action Purpose On all platforms except the Class A Flash file system platforms, the default startup-config file usually is stored in NVRAM.
On the Class A Flash file system platforms, the CONFIG FILE environment variable points to _ the default startup-config file. The CONFIG FILE variable defaults to _ NVRAM. Command or Action Purpose Step 1 enable Example: Device> enable Enables privileged EXEC mode. • Enter your password if prompted. Step 2 configure terminal Example: Device# configure terminal Enters global configuration mode. Step 3 configuration command Example: Device(config)# configuration command Enter the necessary configuration commands. The Cisco IOS documentation set describes configuration commands organized by technology. Step 4 Do one of the following:
• end • ^Z Ends the configuration session and exits to EXEC mode. Note Managing Configuration Files 9