Elastic Compute Service:Create a command

Create a command in the ECS console

1. Log on to the ECS console.

2. In the left-side navigation pane, choose Maintenance & Monitoring > Cloud Assistant.

3. In the top navigation bar, select a region and resource group in which to create a Cloud Assistant command.

   Note

   After you select a resource group to which you want to add the command, you can manage permissions on the command at the resource group level. You can attach required Resource Access Management (RAM) policies to resource groups to manage permissions at the resource group level. For information about RAM policies and how to manage permissions at the resource group level, see the Cloud Assistant command-specific sample custom policies section of the "Use RAM to implement permission control" topic and Classify resources into resource groups and grant permissions on the resource groups.

   

4. In the upper-right corner, click Create/Run Command.

5. In the Command Information section of the Create Command panel, configure the parameters. The following table describes the parameters.

   Parameter	Description
   Command Source	Select a command source. Enter Command Content: Create a command. Select Saved Command: Select an existing command.
   Command Type	Select a command type. For Linux instances, select Shell, Python, or Perl. For Windows instances, select Bat or PowerShell.
   Command content	Enter or paste the command content. For information about shell commands, see View the system configurations of ECS instances. When you create a command, make sure that the syntax, logic, and algorithm of the command are correct. For example, to archive a file to the /backup directory (mkdir /backup) that you created on an instance, enter the following shell command: #!/bin/bash OF=/backup/my-backup-$(date +%Y%m%d).tgz tar -cf $OF {{file}} Note In the preceding sample command, {{file}} is a custom parameter. When you run the command, you can set the custom parameter to the name of the file that you want to archive. Example: /app/usrcredential. You can use custom parameters in scenarios in which dynamic values and values that are shared across multiple commands are required. We recommend that you specify custom parameters for sensitive data or data that changes together with the environment, such as AccessKey pairs, instance IDs, authorization codes, time parameters, and critical system files.
   Use Parameters	Specify whether to use parameters. If you turn on Use Parameters, specify custom parameters in the {{key}} format in the Command content field. Note You can specify up to 20 custom parameters in a single Cloud Assistant command. You can specify built-in environment parameters as custom parameters. When you run the command, the parameters are automatically specified by Cloud Assistant. You can specify the following built-in environment parameters: {{ACS::RegionId}}: the ID of the region. {{ACS::AccountId}}: the unique identifier (UID) of the Alibaba Cloud account. {{ACS::InstanceId}}: the ID of the instance. Note If you want to run the command on multiple instances and specify the {{ACS::InstanceId}} parameter as a built-in environment parameter, make sure that the version of Cloud Assistant Agent is not earlier than the following versions. For more information, see Install Cloud Assistant Agent. Linux: 2.2.3.309 Windows: 2.1.3.309 {{ACS::InstanceName}}: the name of the instance. Note If you want to run the command on multiple instances and specify the {{ACS::InstanceName}} parameter as a built-in environment parameter, make sure that the version of Cloud Assistant Agent is not earlier than the following versions. For more information, see Install Cloud Assistant Agent. Linux: 2.2.3.344 Windows: 2.1.3.344 {{ACS::InvokeId}}: the ID of the command task. Note If you want to specify the {{ACS::InvokeId}} parameter as a built-in environment parameter, make sure that the version of Cloud Assistant Agent is not earlier than the following versions. For more information, see Install Cloud Assistant Agent. Linux: 2.2.3.309 Windows: 2.1.3.309 {{ACS::CommandId}}: the ID of the command. Note If you want to specify the {{ACS::CommandId}} parameter as a built-in environment parameter when you call the RunCommand operation, make sure that the version of Cloud Assistant Agent is not earlier than the following versions. For more information, see Install Cloud Assistant Agent. Linux: 2.2.3.309 Windows: 2.1.3.309
   Execution Plan	Select a command execution plan. Immediate execution: The command is immediately run after you click Run or Run and Save. After the next startup of the system: The command is run the next time the associated instances are started after you click Run or Run and Save. After each system startup: The command is run each time the associated instances are started after you click Run or Run and Save. Run on Schedule: The command is run at a specific interval, at a specific time, or on a schedule after you click Run or Run and Save. The following execution schedule options are available: Run at Fixed Interval: Use a rate expression to specify an interval at which you want to run the command. You can specify the interval in seconds, minutes, hours, or days. This option is suitable for scenarios in which you want to execute command execution tasks at a fixed interval. Note When you specify an interval, take note of the following limits: The specified interval can range 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 that elapses between two consecutive executions. The interval is irrelevant to the amount of time that is required to run the command once. For example, you set the interval to 5 minutes, and the command requires 2 minutes to run once. Each time the command is run, the system waits for 3 minutes before it reruns the command. After you create a task, the task does not immediately run. For example, you set the interval to 5 minutes and create a task to run the command. The task runs 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 the Execution time parameter to May 17, 2022, 17:30:50 and the Time Zone parameter 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 Cron Expression: Use a cron expression to specify a schedule on which you want to run the command. Specify a schedule that is accurate to seconds, minutes, hours, 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 the time zone and runs the command as scheduled. This option provides flexibility and is suitable for scenarios in which you want to execute command tasks on a schedule. For more information about cron expressions, see Cron expressions. Note The minimum interval must be 10 seconds or longer and cannot be shorter than the timeout period of scheduled executions. For example, if you set the Execution Frequency parameter to 0 0 12 ? * WED 2022 and the Time Zone parameter to (GMT+08:00) Asia/Shanghai, the system runs the command at 12:00:00 every Wednesday in 2022 (UTC+8).
   Command Name	Enter a name for the command.
   Command Description	Enter a description for the command. We recommend that you enter identifiable information, such as the purpose of the command, to facilitate management and maintenance.
   Username	Specify a username that you want to use to run the command on ECS instances. For security reasons, we recommend that you run Cloud Assistant commands as a regular user based on the principle of least privilege. 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	Specify a timeout period for running the command 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 the Timeout parameter to a value that is smaller than 10, the system changes the value to 10 to ensure that the command can be run.
   Tag	Specify a tag that you want to add to the command for subsequent classification and management. Tag key: the key of the tag. Tag value: the value of the tag. Note If you select instances and click Run and Save, the system adds the tag to the command and the command execution task. If you select instances and click Run, the system adds the tag only to the command.

6. In the Select Instance 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 not provided by Alibaba Cloud but is managed by Cloud Assistant. For more information, see Alibaba Cloud managed instances.

7. Click Save.

Create a command by using Alibaba Cloud CLI

Sample request

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

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

The following table describes the main parameters. For more information about the parameters, see CreateCommand.

Sample response

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