How to Create and Edit the Junos CLI Configuration
You create or edit your device’s configuration in the configuration mode of the Junos command-line interface (CLI). To enter configuration mode, use the configure command at the operational mode prompt:
wiley@netnik> configure Entering configuration mode  wiley@netnik#
This allows you to create or edit the candidate configuration. Enter set ? after the configuration mode prompt to see the complete list of top-level configuration statements that are available for the set up of your device. These top-level groups organize all Junos configuration statements into hierarchies of related commands.
 wiley@netnik# set ? Possible completions: > chassis Chassis configuration > class-of-service Class-of-service configuration > firewall Define a firewall configuration > forwarding-options Configure options to control packet forwarding > interfaces Interface configuration > policy-options Routing policy option configuration > protocols Routing protocol configuration > routing-instances Routing instance configuration > routing-options Protocol-independent routing option configuration > snmp Simple Network Management Protocol configuration > system System parameters
You use these top-level commands and their underlying hierarchies to set up the various properties of your device. You can enter them into the candidate configuration line by line, copy them as text, or import them from a file. To add a new Gigabit Ethernet interface you would directly enter the appropriate set command via the CLI:
 wiley@netnik# set interfaces ge-1/1/0 unit 0 family inet address 192.168.0.1/24
You can use Junos automation to strictly guide users in making changes to a configuration. By creating an op script for the device, users can perform controlled configuration changes based on supplied input from command-line arguments, interactive prompts, or Junos show commands.
The advantage of this approach is that you can code the structure of the change into the script itself. This mitigates human error and lets users with less expertise change the configuration in controlled ways.