This is going to be the first post in a series of blog posts on IOS XR code. This post might be simple, but it is a good to start with the basics so that poeple can get familiar with how XR works.
Lets cover the prompt real quick as that is a bit different then what people are used to.
Lets look at the standard IOS prompt vs the IOS XR prompt.
IOS: Router#
IOS-XR: RP/0/7/CPU0:ios#
As you can see the prompt is a bit different. In standard IOS you have the hostname, but in IOS XR you get a bit more information. It breaks down as follows:
Prompt Syntax:
Type – type of interface card (Usually RP for Route Processor)
Rack – What Rack number this is installed in in a multi-shelf system, typically 0 if standalone
Slot – Slot the RP is installed in (7)
Module – What execute the user commands or port interface. Usually CPU0 or CPU1
Name – Hostname of the router, default here is IOS
->  RP/0/7/CPU0:ios#


Ok, now lets change the hostname from IOS to R1.
First though, let’s change the hostname on typical IOS so you can see the difference.
Router#
Router#conf t
*Mar 29 16:32:51.507: %SYS-5-CONFIG_I: Configured from console by console
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#hostname R1
R1(config)#
As you can see, in IOS the hostname changed immediately after hitting Enter.
So, let’s change the hostname to R1 on IOS XR code:
RP/0/7/CPU0:ios#
RP/0/7/CPU0:ios#conf t
Thu Mar 29 16:00:43.844 UTC
RP/0/7/CPU0:ios(config)#hostname R1
RP/0/7/CPU0:ios(config)#
Notice that the hostname did not change? In IOS XR you need to COMMIT your changes in order for them to take effect. But before we commit them, let’s do a show config quick.

RP/0/7/CPU0:ios(config)#
RP/0/7/CPU0:ios(config)#sh config
Thu Mar 29 16:03:53.060 UTC
Building configuration…
!! IOS XR Configuration 4.1.1
hostname R1
end
RP/0/7/CPU0:ios(config)#
Pretty cool, the router will show you the changes you are about to make.
Now we can COMMIT the changes
RP/0/7/CPU0:ios(config)#commit
Thu Mar 29 16:03:04.182 UTC
RP/0/7/CPU0:R1(config)#
See, once you entered COMMIT, the hostname change from IOS to R1.