Elastic Compute Service:Create a command

Procedure in the ECS console

1. Log on to the ECS console.
2. In the left-side navigation pane, choose Maintenance & Monitoring > ECS Cloud Assistant.
3. In the top navigation bar, select a region.
4. In the upper-right corner, click Create or Run Command.
5. In the Command Information section, configure the parameters described in the following table.

   Parameter	Description
   Command Source	Select the command source. Enter Command Content: creates a command. Select Saved Command: selects an existing command.
   Command Name	Enter a name for the command.
   Implementation plan	Select a plan on how to run the command. Immediate execution: The command is run immediately after you click Run or Execute and Save. After the next startup of the system: The command is run the next time the selected instances are started after you click Run or Execute and Save. After each system startup: The command is run each time the selected instances are started after you click Run or Execute and Save. Run on Schedule: The command is run at a specified interval, at a specified time, or on a schedule after you click Run or Execute and Save. If you set Implementation plan to Run on Schedule, the following options are available: Run at Fixed Interval: Use a rate expression to specify an interval at which to run the command. You can specify the interval in seconds, minutes, hours, or days. This option is applicable when command execution tasks need to be executed at a fixed interval. Note When you specify an interval, take note of the following limits: The specified interval can be anywhere from 60 seconds to 7 days and must be longer than the timeout period of the scheduled task. The interval is the amount of time elapsed between two consecutive executions. The interval is irrelevant to the amount of time required to run the command once. For example, assume that you set the interval to 5 minutes and that it takes 2 minutes to run the command each time. Each time the command is run, the system waits 3 minutes before it runs the command again. A task is not executed immediately after the task is created. For example, assume that you set the interval to 5 minutes and create a task to run the command. The task begins to run 5 minutes after it is created. Run Only Once at Specified Time: Specify a point in time and a time zone to run the command only once. For example, if you set Execution Time to May 17, 2022, 17:30:50 and Time Zone to (GMT+08:00) Asia/Shanghai, the command was run only once at 17:30:50 on May 17, 2022 (UTC+8). Run on Clock-based Schedule: Use a cron expression to specify a schedule on which to run the command. Specify a schedule accurate to the second, minute, hour, day of the month, month, day of the week, or year, and select a time zone from the Time Zone drop-down list. The system calculates the schedule based on the cron expression and time zone and runs the command as scheduled. This option provides flexibility and is applicable when tasks need to run on a schedule. For more information about cron expressions, see Cron expressions. Note The minimum interval must be 10 seconds or more and cannot be shorter than the timeout period of scheduled executions. For example, if you set Execution Frequency to 0 0 12 ? * WED 2022 and Time Zone to (GMT+08:00) Asia/Shanghai, the system runs the command at 12:00:00 every Wednesday in 2022 (UTC+8).
   Command Type	Select a command type. For Linux instances, select Shell, Python, or Perl. For Windows instances, select Bat or PowerShell.
   Command	Enter or paste the content of the command. For information about sample shell commands, see View instance configurations.
   Use Parameters	Specify whether to use parameters. If you turn on Use Parameters, specify custom parameters in the {{key}} format in the Command field. You can specify built-in environment variables as custom parameters. Then, when you run this command, Cloud Assistant automatically replaces the values in the commands with the environment variables. You can specify the following built-in environment variables: {{ACS::RegionId}}: the ID of the region. {{ACS::AccountId}}: the UID of the Alibaba Cloud account. {{ACS::InstanceId}}: the ID of the instance. Note When the command is run on multiple instances, if you want to specify {{ACS::InstanceId}} as a built-in environment variable, make sure that the version of the Cloud Assistant client is not earlier than the following ones: Linux: 2.2.3.309 Windows: 2.1.3.309 {{ACS::InstanceName}}: the name of the instance. Note When the command is run on multiple instances, if you want to specify {{ACS::InstanceName}} as a built-in environment variable, make sure that the version of the Cloud Assistant client is not earlier than the following ones: Linux: 2.2.3.344 Windows: 2.1.3.344 {{ACS::InvokeId}}: the ID of the command task. Note If you want to specify {{ACS::InvokeId}} as a built-in environment variable, make sure that the version of the Cloud Assistant client is not earlier than the following ones: Linux: 2.2.3.309 Windows: 2.1.3.309 {{ACS::CommandId}}: the ID of the command. Note When you call the RunCommand operation, if you want to specify {{ACS::CommandId}} as a built-in environment variable, make sure that the version of the Cloud Assistant client is not earlier than the following ones: Linux: 2.2.3.309 Windows: 2.1.3.309
   Command Description	Enter a description for the command. We recommend that you enter identifiable command information, such as the purpose of the command, for easy management and maintenance.
   Username	Specify the username to use to run the command on ECS instances. For security purposes, we recommend that you run Cloud Assistant commands based on the least privilege principle as a regular user. For more information, see Run Cloud Assistant commands as a regular user. By default, Cloud Assistant commands are run by the root user on Linux instances and by the system user on Windows instances.
   Execution Path	Specify an execution path for the command. Different default execution paths are provided based on the operating system of instances on which the command is run. For Linux instances, the default execution path is the /home directory of the root user. For Windows instances, the default execution path is C:\Windows\system32.
   Timeout Period	Specify a timeout period for the command to run on instances. If a task that runs the command times out, Cloud Assistant forcefully terminates the task process. Unit: seconds. Default value: 60. Minimum value: 10. If you set Timeout Period to a value of less than 10, the system changes the value to 10 to ensure that the command can be run.
   Tag	Add a tag to the command for future classification, management, and maintenance.

6. In the Select Instances and Select Managed Instances sections, select the instances on which you want to run the command.
   Note A managed instance is an instance that is managed by Cloud Assistant but not provided by Alibaba Cloud. For more information, see Manage servers that are not provided by Alibaba Cloud.
7. Click Save.

Procedure by using the CLI

• Sample request:

  Call the CreateCommand operation to create a Cloud Assistant command named update to update the system of instances.

  aliyun ecs CreateCommand --RegionId 'cn-hangzhou' \
  --CommandContent 'eXVtIHVwZGF0ZSAteQ==' \
  --Type 'RunShellScript' \
  --Name 'update' \
  --Description 'update' \
  --output cols=CommandId

  Note The values enclosed in single quotation marks ('') are example parameter values. Change the values of these parameters based on the actual values of your use case.

  Parameter	Examples	Description
  RegionId	cn-hangzhou	The ID of region in which you want to create the command.
  Name	update	The name of the command.
  Type	RunShellScript	The command type. For Linux instances, set the value to RunShellScript. For Windows instances, set the value to RunBatScript or RunPowershellScript.
  CommandContent	eXVtIHVwZGF0ZSAteQ==	The Base64-encoded content of the command.
  Description	update	The description of the command.

  For more information, see CreateCommand.

• Sample success response:

  CommandId
  ---------
  c-hz018qng4on****