Compare Running Config With A Previous Config

To see what changes have been made to the running config on a Cisco device since the last save, you an do a compare with the startup config.

show archive config differences nvram:startup-config system:running-config

The output shows the differences in the latter file (the running-config, in this case). Any line beginning with a + is an addition. Conversely, anything beginning with a - has been removed.

Example

ROUTER#$show archive config differences nvram:startup-config system:running-config
Contextual Config Diffs:
+interface Vlan3
 +ip address 2.2.2.2 255.255.255.0
interface Vlan2
 -description WAN

You can replace nvram:startup-config with any config that has been archived using the procedure in Automatic Config Archiving.

Example

ROUTER#$show archive config differences tftp://10.10.10.5/ROUTER-autoarchive-May-29-10:11:35.187-EDT-13 system:running-config
Contextual Config Diffs:
+interface Vlan3
 +ip address 2.2.2.2 255.255.255.0
interface Vlan2
 -description WAN

To make your router feel more like a Juniper, add this to your config:

alias exec compare show archive config differences nvram:startup-config system:running-config

Then you just need to type "compare" to see what changes have been made since you last saved your config.