Startup config Issue

Unanswered Question
Mar 7th, 2009

Specifying the Startup Configuration File topic

in below link indicates to save after changing the config_file variable.If we save this the new startup config file will be overwritten by running config and when router reboots it will not boot with the new startup config.How this will work andy suggestions?

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Giuseppe Larosa Sat, 03/07/2009 - 23:35

Hello Mohammad,

be aware that this doesn't apply to all platforms but only to those that have a flash filesystem of type A.


Specifying the CONFIG_FILE Environment Variable on Class A Flash File Systems

To check what type of filesystem you have use the following link:

Hope to help


tahseen12 Sun, 03/08/2009 - 01:57

yes it is right but my question is if we point to new startup config Specifying the CONFIG_FILE Environment Variable and then save Isn't it going to overwrite the new startup with running config.See the steps in the link I attached.

#copy [flash-url | ftp-url | rcp-url | tftp-url | system:running-config | nvram:startup-config] dest-flash-url

#boot config dest-flash-url

#copy system:running-config nvram:startup-config --------This step

Giuseppe Larosa Sun, 03/08/2009 - 06:18

Hello Mohammad,

actually after the command boot config the documentation says:

After you specify a location for the startup configuration file, the nvram:startup-config command is aliased to the new location of the startup configuration file. The more nvram:startup-config EXEC command will display the startup configuration, regardless of its location.

Notice in the example that the config file is copied to the flash file twice:

The following example copies the running configuration file to the first PCMCIA slot of the RSP card in a Cisco 7500 series router. This configuration is then used as the startup configuration when the system is restarted.

Router# copy system:running-config slot0:config2

Router# configure terminal

Router(config)# boot config slot0:config2

Router(config)# end

Router# copy system:running-config nvram:startup-config


the first copy creates the file in the flash and then you need to perform a write mem after the change.

What is showed by sh bootvar in your case ?

Hope to help


tahseen12 Sun, 03/08/2009 - 07:59

Thats what I understand but if I do wr mem let say after having a modified startup,it will be overwritten by running config.This means this is only for changing the config file location but what if I want to boot with completely new startup config.

Is config replace or rollback the right option only but this not there in 12.2

Giuseppe Larosa Mon, 03/09/2009 - 03:32

Hello Mohammad,

yes the documentation tells that the only effect is to change the config file location not to have a rollback ready copy.

Hope to help



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