files can be different. For example, you may want to change the configuration for a short time period rather than permanently. In this case, you would change the running configuration using the configure terminal EXEC command but not save the configuration using the copy running-config startup-config EXEC command. To change the running configuration, use the configure terminal command, as described in the Modifying the Configuration File, on page 9 section. As you use the Cisco IOS configuration modes, commands generally are executed immediately and are saved to the running configuration file either immediately after you enter them or when you exit a configuration mode.
To change the startup configuration file, you can either save the running configuration file to the startup configuration using the copy running-config startup-config EXEC command or copy a configuration file from a file server to the startup configuration (see the “Copying a Configuration File from a TFTP Server to the Router” section for more information). Configuration Mode and Selecting a Configuration Source To enter configuration mode on the device, enter the configure command at the privileged EXEC prompt.
The Cisco IOS software responds with the following prompt asking you to specify the terminal, memory, or a file stored on a network server (network) as the source of configuration commands: Configuring from terminal, memory, or network [terminal]? Configuring from the terminal allows you to enter configuration commands at the command line, as described in the following section. See the “Re-executing the Configuration Commands in the Startup Configuration File” section for more information. Configuring from the network allows you to load and execute configuration commands over the network. See the “Copying a Configuration File from a TFTP Server to the Switch” section for more information.
Configuration File Changes Using the CLI 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 command. Comments are not displayed when you list the startup configuration with the show startup-config or more nvram:startup-config EXEC mode command.
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. Location of Configuration Files Configuration files are stored in the following locations: • The running configuration is stored in RAM. • On all platforms except the Class A Flash file system platforms, the startup configuration is stored in nonvolatile random-access memory (NVRAM).
Managing Configuration Files Configuration Mode and Selecting a Configuration Source Managing Configuration Files 2