Show startup-config – Which information does the show startup-config command display?
Show startup-config shows the router or switch complete configuration saved on the nonvolatile RAM, Information present on the non-volatile RAM is saved even after the device restarts so this configuration is present at the time of the device start-up.
Show start-up config is one of the most common commands by the network administrators as it shows all the config that is useful while checking the device and checking what is configured on the device.
This command can be used for troubleshooting, whenever there is an issue with the device we can copy the complete configuration and flash that on the new device. The new device can be configured instantly using this command so it’s a best practice to always have a backup of the start-up config.
In case of hardware failure, we can quickly use the saved startup-config and configure the new device same as the old one in a few minutes.
We can also delete the start-up config however once deleted, we cannot retrieve the configuration so backing up the config is highly important on the production network or high-traffic network.
The startup-config file is very small in size so backing up the config does not take much space. It is just a text file with configuration data.
By default, on a new Cisco device, the start-up config is not present so we have to save the startup-config on the new device then only it will show up when we will use the command ‘show startup-config’.
To save the running config, we can use the command ‘write’ and to delete it we can use the command ‘write erase’
Below is the output of the ‘show running-config’ command
Router#show startup-config
Using 608 bytes
!
version 15.1
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname Router
!
!
!
!
!
!
!
!
ip cef
no ipv6 cef
!
!
!
!
license udi pid CISCO1941/K9 sn FTX1524P93Q-
!
!
!
!
!
!
!
!
!
!
!
spanning-tree mode pvst
!
!
!
!
!
!
interface GigabitEthernet0/0
no ip address
duplex auto
speed auto
shutdown
!
interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
shutdown
!
interface Vlan1
no ip address
shutdown
!
ip classless
!
ip flow-export version 9
!
!
!
!
!
!
!
line con 0
!
line aux 0
!
line vty 0 4
login
!
!
!
End
The above output is from the new router, we can see that nothing much is configured on the router however, after configuring the router and saving the startup-config, we will see the configuration in the startup-config.
We can use the pipe symbol to filter out the configuration that we want to see
For example, if we want to see the VTY line configuration, we can use the pipe symbol to check the VTY lines.
Show startup-config | begin vty
We can use this command to check any specific configuration present on the device.
