Is Cisco Command Wr As Same As Copy Running-config Startup-config

Is Cisco Command wr the Same as copy running-config startup-config?

This is a frequently asked question among Cisco network administrators, especially those new to the platform. The short answer is: yes, the wr command (short for "write") is essentially the same as the copy running-config startup-config command. Both commands achieve the same fundamental goal: saving the currently running configuration to the startup configuration. However, there are subtle differences worth exploring. This article will delve into the specifics of each command, their functionalities, and their implications for network configuration management.

The copy running-config startup-config command explicitly copies the contents of the currently active running configuration (RAM) to the startup configuration file (NVRAM). This startup configuration is loaded when the device boots up. Therefore, any changes made to the running configuration will be persistent across reboots only after using this command. This ensures configuration preservation even after a power cycle or router crash.

Understanding the wr Command (Write Memory)

The wr command, a shorthand for "write memory," is a Cisco IOS shortcut for the copy running-config startup-config command. It serves the same purpose – saving the current running configuration to the startup configuration file stored in NVRAM. It’s a convenient alternative for experienced network administrators who prefer brevity and efficiency. This command is particularly useful for quickly saving changes after making several configuration adjustments.

Practical Implications and Differences

While functionally equivalent in their primary purpose, there are subtle differences:

• Verbosity: copy running-config startup-config is more explicit and descriptive, making it easier for beginners to understand its function. wr is concise, useful for experienced users but potentially ambiguous for those unfamiliar with the Cisco IOS command-line interface (CLI).

• Error Handling: While both commands provide feedback upon successful completion, the copy running-config startup-config command might offer more detailed error messages in case of failure (e.g., insufficient NVRAM space). This can assist in troubleshooting potential configuration saving issues.

• Context: The copy command offers more flexibility. For example, you can use it to copy configurations between different devices or to specific files. The wr command is strictly limited to saving the running configuration to the startup configuration.

• Readability and Maintainability: In larger configuration management scenarios or when collaborating with other administrators, the longer copy command enhances code readability and simplifies understanding. This is crucial for maintaining consistent and well-documented network configurations.

Best Practices

While both commands achieve the same outcome, using copy running-config startup-config is often recommended, particularly for:

• Clarity and Documentation: It's significantly clearer to other administrators reviewing the configuration scripts or logs.
• Detailed Error Messages: Provides more comprehensive error reporting if the save process encounters a problem.
• Consistency: Maintaining consistent command usage across your configuration scripts makes them easier to maintain and manage.

In summary, while wr provides a convenient shortcut, copy running-config startup-config is generally preferred for its clarity, detailed feedback, and better alignment with best practices in network configuration management. Ultimately, choosing between the two commands depends on individual preference and team standards, but understanding their functional equivalence and subtle differences is crucial for efficient Cisco network administration. Remember to always verify your configuration after saving using the show running-config command.