Obtaining Environment Variable

Interface Name

Obtaining environment variable

Application Phase

Subscription and execution phases

API Prototype

result1_value, result2_description = ops.environment.get(envName)

Description

Return Value

The result1_value and result2_description in the API prototype indicate return values.

The first return value is an environment variable value, and is a character string or digit. If the first return value is a digit, it must be converted through int(). If the first return value is a character string, None indicates a failure.

The second return value is a string of characters indicating the results. When the first return value is the environment variable value, Success is displayed. If the first return value is None, the failure cause is displayed.

Usage Description

An environment variable consists of a name and a value. Currently, OPS supports system and user-defined environment variables.

• System environment variables

  Environment variables supported by the device by default cannot be created, deleted, or modified. A system environment variable name starts with an underscore (_), and a system environment variable value is determined by the system.

  System environment variables include:

  • Public environment variables: can be used for all types of events.

  • Non-public environment variables: can only be used for specified events. Its value is obtained when an event is triggered and indicates some information about the event.

  Table 7-3 shows system environment variables currently supported by the OPS.

  Table 7-3 System environment variables

  Event	Environment Variable Name	Environment Variable Description	Application Phase
  All events	_event_name	Event name	Execution phase
  	_event_datetime	Time when an event is received	Execution phase
  	_assistant_name	Assistant name, or script name	Subscription and execution phases
  	_sysname	Device name	Subscription and execution phases
  	_phase	Script execution phase	Subscription and execution phases
  	_event_hits	Number of times the current event occurs within the last period	Execution phase
  CLI	_cli_input	Command entered by a user (an incomplete keyword, such as dis dev)	Execution phase
  	_cli_command	User entered command (a complete keyword, such as display device)	Execution phase
  	_cli_view	CLI view name	Execution phase
  	_cli_trigger	CLI triggering point	Execution phase
  	_cli_vty	User channel	Execution phase
  	_cli_ip	User channel IP address	Execution phase
  Timer	_timer_type	Timer type	Execution phase
  Route change	_routing_network	Network prefix	Execution phase
  	_routing_mask	Network mask	Execution phase
  	_routing_protocol	Network protocol	Execution phase
  	_routing_type	Change type	Execution phase
  	_routing_nexthop	Next hop	Execution phase
  	_routing_interface	Interface name	Execution phase
  Log	_iclog_module	Log module name	Execution phase
  	_iclog_level	Log severity	Execution phase
  	_iclog_alias	Log alias	Execution phase
  	_iclog_content	Log contents	Execution phase
  	_iclog_time	Log generation time	Execution phase
  Trap	_trap_module	Trap module name	Execution phase
  	_trap_level	Trap severity	Execution phase
  	_trap_alias	Trap alias	Execution phase
  	_trap_content	Trap contents	Execution phase
  	_trap_time	Trap generation time	Execution phase
  	_trap_oid	Trap OID	Execution phase
  LLDP neighbor change	_lldp_interface	Interface on which the neighbor status changes	Execution phase
  	_lldp_devtype	Type of a neighbor device	Execution phase
  	_lldp_event	Event triggering type	Execution phase
  Stack status change	_dev_event	Event name	Execution phase
  	_dev_slot	Stack ID	Execution phase

• User-defined environment variables

  In a Python script, you can input an environment variable name in the location where a parameter needs to be input to indicate that an environment variable value needs to be referenced. When the system is running a Python script, it replaces an environment variable name with an environment variable value. To change the value, you can directly change it on the device without having to change and install the Python script. You can define and use user-defined environment variables to simplify the configuration and improve flexibility and feasibility of the Python script.

  User-define environment variables start with letters, can contain letters, digits, and an underscore (_), apply to all types of events, and can be used in subscription and execution phases. The value of a user-defined environment variable can be configured using the environment command. You can create, modify, and delete user-defined variables.

If the subscription event does not occur, some environment variables related to the event cannot be obtained.

Example

Using the Command Line Event Subscription API, you can subscribe to commands run on a device. When a subscription event is matched, the user wants to view information about the command.

value, loginfo = ops.environment.get("_cli_view")