Create a command - Deployment & Maintenance| Alibaba Cloud Documentation Center

You can use Cloud Assistant commands to perform routine tasks on ECS instances. These tasks include running automated O&M scripts, polling processes, resetting user passwords, installing or uninstalling software, updating applications, and installing patches. Command types can be batch or PowerShell for Windows instances, and shell for Linux instances. You can specify custom parameters as variables in Cloud Assistant commands.

Background information

You can retain a maximum of 100 Cloud Assistant commands within an Alibaba Cloud region. This quota may increase based on your ECS usage. For more information about how to view the quota, see Step 1: View resource quotas. If you click Run when you are creating a command, the command does not count against your command quota.

Note You can also call the DescribeAccountAttributes operation with AttributeName.N set to max-axt-command-count to query the maximum number of Cloud Assistant commands that you can retain within a region.
A command cannot exceed 16 KB in size after it is encoded in Base64.
A maximum of 20 custom parameters can be specified in a Cloud Assistant command.
When you create a command, you must check whether the syntax, logic, and algorithm of the command are correct.
For example, assume that you have created the /backup directory (mkdir /backup) on an instance, you can run the following shell commands to archive a file in this directory:
```
#!/bin/bash 
OF=/backup/my-backup-$(date +%Y%m%d).tgz
tar -cf $OF {{file}}
```
Note In the preceding example, {{file}} is a custom parameter. When you run the commands, you can set this custom parameter to the name of the file to be archived. Example: /app/usrcredential. Custom parameters can be used in scenarios of dynamic values and multi-purpose values. We recommend that you specify custom parameters for security-sensitive data or data that changes based on the environment, including AccessKey pairs, instance IDs, authorization codes, time parameters, and critical system files.

Procedure in the console

Log on to the ECS console.
In the left-side navigation pane, choose Maintenance & Monitoring > ECS Cloud Assistant.
In the top navigation bar, select a region.
Click Create or Run Command.

In the Command Information section, configure the parameters described in the following table.


Parameter	Description
Command Source	The source of the command. Enter Command Content: creates a command. Select Saved Command: selects an existing command.
Command Name	The name of the command.
Implementation plan	The command execution time. Immediate execution: If this value is selected, the command is run immediately after you click Run or Execute and Save. After the next startup of the system: If this value is selected, the command is run the next time the selected instances are started after you click Run or Execute and Save. After each system startup: If this value is selected, the command is run each time the selected instances are started after you click Run or Execute and Save.
Command Type	The type of the command. For Linux instances, select Shell. For Windows instances, select Bat or PowerShell.
Command	The content of the command. You can enter or paste the command content. For more information about shell commands, see View instance configurations.
Use Parameters	Specifies whether to use parameters. If you turn on Use Parameters, you can specify custom parameters in the `{{key}}` format in the Command field.
Command Parameters	The values of the custom parameters specified in the `{{key}}` format in the Command field. This parameter is available only when Use Parameters is turned on. Note You can use the parameter store of Operation Orchestration Service (OOS) in Cloud Assistant commands. For more information, see Use OOS Parameter Store in Cloud Assistant commands
Command Description	The description of the command. We recommend that you enter information such as the purpose of the command to make it easier to manage and maintain.
Username	The name of the user running the command on the ECS instance. The best practice in permission management is to run commands based on the least privilege principle. We recommend that you run Cloud Assistant commands 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.
Password Name	The password of the execution user that is hosted in Operation Orchestration Service (OOS). This parameter is required only when the command is run by a regular user other than the system user on Windows instances. If the password of the execution user is not hosted in OOS, you must create and host the password in the parameter store of OOS. For more information, see Run Cloud Assistant commands on Windows instances as a regular user.
Execution Path	The custom execution path of the command. The following list provides default execution paths for instances that use different operating systems: For Linux instances, the default execution path is the /home directory of the root user. For Windows instances, the default execution path is the directory where the process of the Cloud Assistant client is located. Example: C:\ProgramData\aliyun\assist\$(version).
Timeout Period	The timeout period for the command to run on instances. If a task that runs a command times out, Cloud Assistant forcibly stops 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 execution succeeds.

In the Select Instances section, select the instances on which you want to run the command.
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 on instances.

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

Note Values enclosed within single quotation marks ('') are example values of the parameters and must be changed based on actual conditions.


Parameter	Example	Description
RegionId	cn-hangzhou	The region ID.
Name	update	The name of the command.
Type	RunShellScript	The type of the command. For Linux instances, set the value to RunShellScript. For Windows instances, the valid values are RunBatScript and 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****
```

What to do next

After the command is created, you can view its detailed information on the Commands tab. For information about how to run this command on a specific instance, see Run a command.

Note If you turn on Use Parameters when you create a command, you must enter parameter values in the Command Parameters fields when you run the command.