Courseiva
SystemPrivileged EXEC

write memory

Saves the current running configuration to the startup configuration in NVRAM, ensuring changes persist after a reload.

Syntax·Privileged EXEC
write memory

When to Use This Command

  • After making configuration changes on a router or switch, use this command to save them so they survive a reboot.
  • Before performing a reload or power cycle, run this command to preserve the current configuration.
  • When deploying a new device, after initial configuration is complete, save the configuration to NVRAM.
  • After troubleshooting and applying a fix, save the configuration to ensure the fix is permanent.

Command Examples

Basic save of running configuration

write memory
Building configuration...
[OK]

The output 'Building configuration...' indicates the router is compiling the running config into a format for NVRAM. '[OK]' confirms the save was successful.

Alternative command with same effect

copy running-config startup-config
Destination filename [startup-config]? 
Building configuration...
[OK]

This is the longer form of the same command. It prompts for a filename (default is startup-config). Press Enter to accept. The output confirms success.

Understanding the Output

The output of 'write memory' is minimal. It first displays 'Building configuration...' which means the router is processing the running configuration and preparing to write it to NVRAM. Then it shows '[OK]' to indicate the write was successful. If there is an error (e.g., NVRAM full or hardware failure), you might see 'Error writing to NVRAM' or similar. A successful save is critical for configuration persistence; without it, all changes are lost on reload.

CCNA Exam Tips

1.

CCNA exam tip: 'write memory' and 'copy running-config startup-config' are equivalent; know both.

2.

CCNA exam tip: The command must be executed in Privileged EXEC mode (enable mode).

3.

CCNA exam tip: If you forget to save, a reload will revert to the last saved configuration.

4.

CCNA exam tip: On some older IOS versions, 'write memory' is deprecated but still works.

Common Mistakes

Mistake 1: Running 'write memory' in User EXEC mode (>) instead of Privileged EXEC mode (#) — results in '% Invalid input detected'.

Mistake 2: Assuming 'write memory' saves to a remote server (it saves to local NVRAM).

Mistake 3: Forgetting to save after making changes, then reloading and losing all changes.

Related Commands

show running-config

Displays the current active configuration in DRAM, showing all non-default settings.

show startup-config

Displays the saved configuration stored in NVRAM that loads on next device boot.

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