AWS Data Pipeline is no longer available to new customers. Existing customers of AWS Data Pipeline can continue to use the service as normal. [Learn more](https://aws.amazon.com/blogs/big-data/migrate-workloads-from-aws-data-pipeline/)

# Preconditions
<a name="dp-object-preconditions"></a>

The following are the AWS Data Pipeline precondition objects:

**Topics**
+ [DynamoDBDataExists](dp-dynamodbdataexists.md)
+ [DynamoDBTableExists](dp-dynamodbtableexists.md)
+ [Exists](dp-object-exists.md)
+ [S3KeyExists](dp-object-S3KeyExists.md)
+ [S3PrefixNotEmpty](dp-object-s3prefixnotempty.md)
+ [ShellCommandPrecondition](dp-object-shellcommandprecondition.md)

# DynamoDBDataExists
<a name="dp-dynamodbdataexists"></a>

 A precondition to check that data exists in a DynamoDB table. 

## Syntax
<a name="dp-dynamodbdataexists-syntax"></a>


****  

| Required Fields | Description | Slot Type | 
| --- | --- | --- | 
| role | Specifies the role to be used to execute the precondition. | String | 
| tableName | DynamoDB Table to check. | String | 

 


****  

| Optional Fields | Description | Slot Type | 
| --- | --- | --- | 
| attemptStatus | Most recently reported status from the remote activity. | String | 
| attemptTimeout | Timeout for remote work completion. If set then a remote activity that does not complete within the set time of starting may be retried. | Period | 
| failureAndRerunMode | Describes consumer node behavior when dependencies fail or are rerun | Enumeration | 
| lateAfterTimeout | The elapsed time after pipeline start within which the object must complete. It is triggered only when the schedule type is not set to ondemand. | Period | 
| maximumRetries | Maximum number attempt retries on failure | Integer | 
| onFail | An action to run when current object fails. | Reference Object, e.g. "onFail":\$1"ref":"myActionId"\$1 | 
| onLateAction | Actions that should be triggered if an object has not yet been scheduled or still not completed. | Reference Object, e.g. "onLateAction":\$1"ref":"myActionId"\$1 | 
| onSuccess | An action to run when current object succeeds. | Reference Object, e.g. "onSuccess":\$1"ref":"myActionId"\$1 | 
| parent | Parent of the current object from which slots will be inherited. | Reference Object, e.g. "parent":\$1"ref":"myBaseObjectId"\$1 | 
| preconditionTimeout | The period from start after which precondition is marked as failed if still not satisfied | Period | 
| reportProgressTimeout | Timeout for remote work successive calls to reportProgress. If set, then remote activities that do not report progress for the specified period may be considered stalled and so retried. | Period | 
| retryDelay | The timeout duration between two retry attempts. | Period | 

 


****  

| Runtime Fields | Description | Slot Type | 
| --- | --- | --- | 
| @activeInstances | List of the currently scheduled active instance objects. | Reference Object, e.g. "activeInstances":\$1"ref":"myRunnableObjectId"\$1 | 
| @actualEndTime | Time when the execution of this object finished. | DateTime | 
| @actualStartTime | Time when the execution of this object started. | DateTime | 
| cancellationReason | The cancellationReason if this object was cancelled. | String | 
| @cascadeFailedOn | Description of dependency chain the object failed on. | Reference Object, e.g. "cascadeFailedOn":\$1"ref":"myRunnableObjectId"\$1 | 
| currentRetryCount | Number of times the precondition was tried in this attempt. | String | 
| emrStepLog | EMR step logs available only on EMR activity attempts | String | 
| errorId | The errorId if this object failed. | String | 
| errorMessage | The errorMessage if this object failed. | String | 
| errorStackTrace | The error stack trace if this object failed. | String | 
| hadoopJobLog | Hadoop job logs available on attempts for EMR-based activities. | String | 
| hostname | The host name of client that picked up the task attempt. | String | 
| lastRetryTime | Last time when the precondition was tried within this attempt. | String | 
| node | The node for which this precondition is being performed | Reference Object, e.g. "node":\$1"ref":"myRunnableObjectId"\$1 | 
| reportProgressTime | Most recent time that remote activity reported progress. | DateTime | 
| @scheduledEndTime | Schedule end time for object. | DateTime | 
| @scheduledStartTime | Schedule start time for object. | DateTime | 
| @status | The status of this object. | String | 
| @version | Pipeline version the object was created with. | String | 
| @waitingOn | Description of list of dependencies this object is waiting on. | Reference Object, e.g. "waitingOn":\$1"ref":"myRunnableObjectId"\$1 | 

 


****  

| System Fields | Description | Slot Type | 
| --- | --- | --- | 
| @error | Error describing the ill-formed object. | String | 
| @pipelineId | Id of the pipeline to which this object belongs. | String | 
| @sphere | The sphere of an object denotes its place in the lifecycle: Component Objects give rise to Instance Objects which execute Attempt Objects. | String | 

# DynamoDBTableExists
<a name="dp-dynamodbtableexists"></a>

 A precondition to check that the DynamoDB table exists. 

## Syntax
<a name="dp-dynamodbtableexists-syntax"></a>


****  

| Required Fields | Description | Slot Type | 
| --- | --- | --- | 
| role | Specifies the role to be used to execute the precondition. | String | 
| tableName | DynamoDB Table to check. | String | 

 


****  

| Optional Fields | Description | Slot Type | 
| --- | --- | --- | 
| attemptStatus | Most recently reported status from the remote activity. | String | 
| attemptTimeout | Timeout for remote work completion. If set then a remote activity that does not complete within the set time of starting may be retried. | Period | 
| failureAndRerunMode | Describes consumer node behavior when dependencies fail or are rerun | Enumeration | 
| lateAfterTimeout | The elapsed time after pipeline start within which the object must complete. It is triggered only when the schedule type is not set to ondemand. | Period | 
| maximumRetries | Maximum number attempt retries on failure | Integer | 
| onFail | An action to run when current object fails. | Reference Object, e.g. "onFail":\$1"ref":"myActionId"\$1 | 
| onLateAction | Actions that should be triggered if an object has not yet been scheduled or still not completed. | Reference Object, e.g. "onLateAction":\$1"ref":"myActionId"\$1 | 
| onSuccess | An action to run when current object succeeds. | Reference Object, e.g. "onSuccess":\$1"ref":"myActionId"\$1 | 
| parent | Parent of the current object from which slots will be inherited. | Reference Object, e.g. "parent":\$1"ref":"myBaseObjectId"\$1 | 
| preconditionTimeout | The period from start after which precondition is marked as failed if still not satisfied | Period | 
| reportProgressTimeout | Timeout for remote work successive calls to reportProgress. If set, then remote activities that do not report progress for the specified period may be considered stalled and so retried. | Period | 
| retryDelay | The timeout duration between two retry attempts. | Period | 

 


****  

| Runtime Fields | Description | Slot Type | 
| --- | --- | --- | 
| @activeInstances | List of the currently scheduled active instance objects. | Reference Object, e.g. "activeInstances":\$1"ref":"myRunnableObjectId"\$1 | 
| @actualEndTime | Time when the execution of this object finished. | DateTime | 
| @actualStartTime | Time when the execution of this object started. | DateTime | 
| cancellationReason | The cancellationReason if this object was cancelled. | String | 
| @cascadeFailedOn | Description of dependency chain the object failed on. | Reference Object, e.g. "cascadeFailedOn":\$1"ref":"myRunnableObjectId"\$1 | 
| currentRetryCount | Number of times the precondition was tried in this attempt. | String | 
| emrStepLog | EMR step logs available only on EMR activity attempts | String | 
| errorId | The errorId if this object failed. | String | 
| errorMessage | The errorMessage if this object failed. | String | 
| errorStackTrace | The error stack trace if this object failed. | String | 
| hadoopJobLog | Hadoop job logs available on attempts for EMR-based activities. | String | 
| hostname | The host name of client that picked up the task attempt. | String | 
| lastRetryTime | Last time when the precondition was tried within this attempt. | String | 
| node | The node for which this precondition is being performed | Reference Object, e.g. "node":\$1"ref":"myRunnableObjectId"\$1 | 
| reportProgressTime | Most recent time that remote activity reported progress. | DateTime | 
| @scheduledEndTime | Schedule end time for object | DateTime | 
| @scheduledStartTime | Schedule start time for object | DateTime | 
| @status | The status of this object. | String | 
| @version | Pipeline version the object was created with. | String | 
| @waitingOn | Description of list of dependencies this object is waiting on. | Reference Object, e.g. "waitingOn":\$1"ref":"myRunnableObjectId"\$1 | 

 


****  

| System Fields | Description | Slot Type | 
| --- | --- | --- | 
| @error | Error describing the ill-formed object | String | 
| @pipelineId | Id of the pipeline to which this object belongs to | String | 
| @sphere | The sphere of an object denotes its place in the lifecycle: Component Objects give rise to Instance Objects which execute Attempt Objects | String | 

# Exists
<a name="dp-object-exists"></a>

 Checks whether a data node object exists. 

**Note**  
We recommend that you use system-managed preconditions instead. For more information, see [Preconditions](dp-concepts-preconditions.md).

## Example
<a name="exists-example"></a>

The following is an example of this object type. The `InputData` object references this object, `Ready`, plus another object that you'd define in the same pipeline definition file. `CopyPeriod` is a `Schedule` object.

```
{
  "id" : "InputData",
  "type" : "S3DataNode",
  "schedule" : { "ref" : "CopyPeriod" },
  "filePath" : "s3://amzn-s3-demo-bucket/InputData/#{@scheduledStartTime.format('YYYY-MM-dd-hh:mm')}.csv",
  "precondition" : { "ref" : "Ready" }
},
{
  "id" : "Ready",
  "type" : "Exists"
}
```

## Syntax
<a name="exists-syntax"></a>


****  

| Optional Fields | Description | Slot Type | 
| --- | --- | --- | 
| attemptStatus | Most recently reported status from the remote activity. | String | 
| attemptTimeout | Timeout for remote work completion. If set then a remote activity that does not complete within the set time of starting may be retried. | Period | 
| failureAndRerunMode | Describes consumer node behavior when dependencies fail or are rerun. | Enumeration | 
| lateAfterTimeout | The elapsed time after pipeline start within which the object must complete. It is triggered only when the schedule type is not set to ondemand. | Period | 
| maximumRetries | Maximum number attempt retries on failure | Integer | 
| onFail | An action to run when current object fails. | Reference Object, e.g. "onFail":\$1"ref":"myActionId"\$1 | 
| onLateAction | Actions that should be triggered if an object has not yet been scheduled or still not completed. | Reference Object, e.g. "onLateAction":\$1"ref":"myActionId"\$1 | 
| onSuccess | An action to run when current object succeeds. | Reference Object, e.g. "onSuccess":\$1"ref":"myActionId"\$1 | 
| parent | Parent of the current object from which slots will be inherited. | Reference Object, e.g. "parent":\$1"ref":"myBaseObjectId"\$1 | 
| preconditionTimeout | The period from start after which precondition is marked as failed if still not satisfied | Period | 
| reportProgressTimeout | Timeout for remote work successive calls to reportProgress. If set, then remote activities that do not report progress for the specified period may be considered stalled and so retried. | Period | 
| retryDelay | The timeout duration between two retry attempts. | Period | 

 


****  

| Runtime Fields | Description | Slot Type | 
| --- | --- | --- | 
| @activeInstances | List of the currently scheduled active instance objects. | Reference Object, e.g. "activeInstances":\$1"ref":"myRunnableObjectId"\$1 | 
| @actualEndTime | Time when the execution of this object finished. | DateTime | 
| @actualStartTime | Time when the execution of this object started. | DateTime | 
| cancellationReason | The cancellationReason if this object was cancelled. | String | 
| @cascadeFailedOn | Description of the dependency chain the object failed on. | Reference Object, e.g. "cascadeFailedOn":\$1"ref":"myRunnableObjectId"\$1 | 
| emrStepLog | EMR step logs available only on EMR activity attempts | String | 
| errorId | The errorId if this object failed. | String | 
| errorMessage | The errorMessage if this object failed. | String | 
| errorStackTrace | The error stack trace if this object failed. | String | 
| hadoopJobLog | Hadoop job logs available on attempts for EMR-based activities. | String | 
| hostname | The host name of client that picked up the task attempt. | String | 
| node | The node for which this precondition is being performed. | Reference Object, e.g. "node":\$1"ref":"myRunnableObjectId"\$1 | 
| reportProgressTime | Most recent time that remote activity reported progress. | DateTime | 
| @scheduledEndTime | Schedule end time for object. | DateTime | 
| @scheduledStartTime | Schedule start time for object. | DateTime | 
| @status | The status of this object. | String | 
| @version | Pipeline version the object was created with. | String | 
| @waitingOn | Description of list of dependencies this object is waiting on. | Reference Object, e.g. "waitingOn":\$1"ref":"myRunnableObjectId"\$1 | 

 


****  

| System Fields | Description | Slot Type | 
| --- | --- | --- | 
| @error | Error describing the ill-formed object. | String | 
| @pipelineId | Id of the pipeline to which this object belongs to. | String | 
| @sphere | The sphere of an object denotes its place in the lifecycle: Component Objects give rise to Instance Objects which execute Attempt Objects. | String | 

## See Also
<a name="exists-seealso"></a>
+ [ShellCommandPrecondition](dp-object-shellcommandprecondition.md)

# S3KeyExists
<a name="dp-object-S3KeyExists"></a>

 Checks whether a key exists in an Amazon S3 data node.

## Example
<a name="dp-object-S3KeyExists-example"></a>

The following is an example of this object type. The precondition will trigger when the key, `s3://amzn-s3-demo-bucket/mykey`, referenced by the `s3Key` parameter, exists. 

```
{
"id" : "InputReady",
"type" : "S3KeyExists",
"role" : "test-role",
"s3Key" : "s3://amzn-s3-demo-bucket/mykey"
}
```

You can also use `S3KeyExists` as a precondition on the second pipeline that waits for the first pipeline to finish. To do so:

1. Write a file to Amazon S3 at the end of the first pipeline's completion.

1. Create an `S3KeyExists` precondition on the second pipeline.

## Syntax
<a name="S3KeyExists-syntax"></a>


****  

| Required Fields | Description | Slot Type | 
| --- | --- | --- | 
| role | Specifies the role to be used to execute the precondition. | String | 
| s3Key | The Amazon S3 key. | String | 

 


****  

| Optional Fields | Description | Slot Type | 
| --- | --- | --- | 
| attemptStatus | Most recently reported status from the remote activity. | String | 
| attemptTimeout | Timeout before attempting to complete remote work one more time. If set, then a remote activity that does not complete within the set time after starting is attempted again. | Period | 
| failureAndRerunMode | Describes consumer node behavior when dependencies fail or are rerun. | Enumeration | 
| lateAfterTimeout | The elapsed time after pipeline start within which the object must complete. It is triggered only when the schedule type is not set to ondemand. | Period | 
| maximumRetries | Maximum number of attempts that are initiated on failure. | Integer | 
| onFail | An action to run when current object fails. | Reference Object, e.g. "onFail":\$1"ref":"myActionId"\$1 | 
| onLateAction | Actions that should be triggered if an object has not yet been scheduled or still not completed. | Reference Object, e.g. "onLateAction":\$1"ref":"myActionId"\$1 | 
| onSuccess | An action to run when current object succeeds. | Reference Object, e.g. "onSuccess":\$1"ref":"myActionId"\$1 | 
| parent | Parent of the current object from which slots will be inherited. | Reference Object, e.g. "parent":\$1"ref":"myBaseObjectId"\$1 | 
| preconditionTimeout | The period from start after which precondition is marked as failed if still not satisfied. | Period | 
| reportProgressTimeout | Timeout for remote work successive calls to reportProgress. If set, then remote activities that do not report progress for the specified period may be considered stalled and are retried. | Period | 
| retryDelay | The timeout duration between two successive attempts. | Period | 

 


****  

| Runtime Fields | Description | Slot Type | 
| --- | --- | --- | 
| @activeInstances | List of the currently scheduled active instance objects. | Reference Object, e.g. "activeInstances":\$1"ref":"myRunnableObjectId"\$1 | 
| @actualEndTime | Time when the execution of this object finished. | DateTime | 
| @actualStartTime | Time when the execution of this object started. | DateTime | 
| cancellationReason | The cancellationReason if this object was cancelled. | String | 
| @cascadeFailedOn | Description of the dependency chain the object failed on. | Reference Object, e.g. "cascadeFailedOn":\$1"ref":"myRunnableObjectId"\$1 | 
| currentRetryCount | Number of times the precondition was tried in this attempt. | String | 
| emrStepLog | EMR step logs available only on EMR activity attempts | String | 
| errorId | The errorId if this object failed. | String | 
| errorMessage | The errorMessage if this object failed. | String | 
| errorStackTrace | The error stack trace if this object failed. | String | 
| hadoopJobLog | Hadoop job logs available on attempts for EMR-based activities. | String | 
| hostname | The host name of client that picked up the task attempt. | String | 
| lastRetryTime | Last time when the precondition was tried within this attempt. | String | 
| node | The node for which this precondition is being performed | Reference Object, e.g. "node":\$1"ref":"myRunnableObjectId"\$1 | 
| reportProgressTime | Most recent time that remote activity reported progress. | DateTime | 
| @scheduledEndTime | Schedule end time for object | DateTime | 
| @scheduledStartTime | Schedule start time for object | DateTime | 
| @status | The status of this object. | String | 
| @version | Pipeline version the object was created with. | String | 
| @waitingOn | Description of list of dependencies this object is waiting on. | Reference Object, e.g. "waitingOn":\$1"ref":"myRunnableObjectId"\$1 | 

 


****  

| System Fields | Description | Slot Type | 
| --- | --- | --- | 
| @error | Error describing the ill-formed object | String | 
| @pipelineId | Id of the pipeline to which this object belongs to | String | 
| @sphere | The sphere of an object denotes its place in the lifecycle: Component Objects give rise to Instance Objects which execute Attempt Objects | String | 

## See Also
<a name="S3KeyExists-seealso"></a>
+ [ShellCommandPrecondition](dp-object-shellcommandprecondition.md)

# S3PrefixNotEmpty
<a name="dp-object-s3prefixnotempty"></a>

A precondition to check that the Amazon S3 objects with the given prefix (represented as a URI) are present.

## Example
<a name="s3prefixnotempty-example"></a>

The following is an example of this object type using required, optional, and expression fields.

```
{
  "id" : "InputReady",
  "type" : "S3PrefixNotEmpty",
  "role" : "test-role",
  "s3Prefix" : "#{node.filePath}"
}
```

## Syntax
<a name="s3prefixnotempty-syntax"></a>


****  

| Required Fields | Description | Slot Type | 
| --- | --- | --- | 
| role | Specifies the role to be used to execute the precondition. | String | 
| s3Prefix | The Amazon S3 prefix to check for existence of objects. | String | 

 


****  

| Optional Fields | Description | Slot Type | 
| --- | --- | --- | 
| attemptStatus | Most recently reported status from the remote activity. | String | 
| attemptTimeout | Timeout for remote work completion. If set then a remote activity that does not complete within the set time of starting may be retried. | Period | 
| failureAndRerunMode | Describes consumer node behavior when dependencies fail or are rerun | Enumeration | 
| lateAfterTimeout | The elapsed time after pipeline start within which the object must complete. It is triggered only when the schedule type is not set to ondemand. | Period | 
| maximumRetries | Maximum number attempt retries on failure | Integer | 
| onFail | An action to run when current object fails. | Reference Object, e.g. "onFail":\$1"ref":"myActionId"\$1 | 
| onLateAction | Actions that should be triggered if an object has not yet been scheduled or still not completed. | Reference Object, e.g. "onLateAction":\$1"ref":"myActionId"\$1 | 
| onSuccess | An action to run when current object succeeds. | Reference Object, e.g. "onSuccess":\$1"ref":"myActionId"\$1 | 
| parent | Parent of the current object from which slots will be inherited. | Reference Object, e.g. "parent":\$1"ref":"myBaseObjectId"\$1 | 
| preconditionTimeout | The period from start after which precondition is marked as failed if still not satisfied | Period | 
| reportProgressTimeout | Timeout for remote work successive calls to reportProgress. If set, then remote activities that do not report progress for the specified period may be considered stalled and so retried. | Period | 
| retryDelay | The timeout duration between two retry attempts. | Period | 

 


****  

| Runtime Fields | Description | Slot Type | 
| --- | --- | --- | 
| @activeInstances | List of the currently scheduled active instance objects. | Reference Object, e.g. "activeInstances":\$1"ref":"myRunnableObjectId"\$1 | 
| @actualEndTime | Time when the execution of this object finished. | DateTime | 
| @actualStartTime | Time when the execution of this object started. | DateTime | 
| cancellationReason | The cancellationReason if this object was cancelled. | String | 
| @cascadeFailedOn | Description of the dependency chain the object failed on. | Reference Object, e.g. "cascadeFailedOn":\$1"ref":"myRunnableObjectId"\$1 | 
| currentRetryCount | Number of times the precondition was tried in this attempt. | String | 
| emrStepLog | EMR step logs available only on EMR activity attempts | String | 
| errorId | The errorId if this object failed. | String | 
| errorMessage | The errorMessage if this object failed. | String | 
| errorStackTrace | The error stack trace if this object failed. | String | 
| hadoopJobLog | Hadoop job logs available on attempts for EMR-based activities. | String | 
| hostname | The host name of client that picked up the task attempt. | String | 
| lastRetryTime | Last time when the precondition was tried within this attempt. | String | 
| node | The node for which this precondition is being performed. | Reference Object, e.g. "node":\$1"ref":"myRunnableObjectId"\$1 | 
| reportProgressTime | Most recent time that remote activity reported progress. | DateTime | 
| @scheduledEndTime | Schedule end time for object. | DateTime | 
| @scheduledStartTime | Schedule start time for object. | DateTime | 
| @status | The status of this object. | String | 
| @version | Pipeline version the object was created with. | String | 
| @waitingOn | Description of list of dependencies this object is waiting on. | Reference Object, e.g. "waitingOn":\$1"ref":"myRunnableObjectId"\$1 | 

 


****  

| System Fields | Description | Slot Type | 
| --- | --- | --- | 
| @error | Error describing the ill-formed object | String | 
| @pipelineId | Id of the pipeline to which this object belongs to | String | 
| @sphere | The sphere of an object denotes its place in the lifecycle: Component Objects give rise to Instance Objects which execute Attempt Objects | String | 

## See Also
<a name="s3prefixnotempty-seealso"></a>
+ [ShellCommandPrecondition](dp-object-shellcommandprecondition.md)

# ShellCommandPrecondition
<a name="dp-object-shellcommandprecondition"></a>

 A Unix/Linux shell command that can be run as a precondition. 

## Example
<a name="shellcommandprecondition-example"></a>

The following is an example of this object type.

```
{
  "id" : "VerifyDataReadiness",
  "type" : "ShellCommandPrecondition",
  "command" : "perl check-data-ready.pl"
}
```

## Syntax
<a name="shellcommandprecondition-syntax"></a>


****  

| Required Group (One of the following is required) | Description | Slot Type | 
| --- | --- | --- | 
| command | The command to run. This value and any associated parameters must function in the environment from which you are running the Task Runner. | String | 
| scriptUri | An Amazon S3 URI path for a file to download and run as a shell command. Only one scriptUri or command field should be present. scriptUri cannot use parameters, use command instead. | String | 

 


****  

| Optional Fields | Description | Slot Type | 
| --- | --- | --- | 
| attemptStatus | Most recently reported status from the remote activity. | String | 
| attemptTimeout | Timeout for remote work completion. If set then a remote activity that does not complete within the set time of starting may be retried. | Period | 
| failureAndRerunMode | Describes consumer node behavior when dependencies fail or are rerun | Enumeration | 
| lateAfterTimeout | The elapsed time after pipeline start within which the object must complete. It is triggered only when the schedule type is not set to ondemand. | Period | 
| maximumRetries | Maximum number attempt retries on failure | Integer | 
| onFail | An action to run when current object fails. | Reference Object, e.g. "onFail":\$1"ref":"myActionId"\$1 | 
| onLateAction | Actions that should be triggered if an object has not yet been scheduled or still not completed. | Reference Object, e.g. "onLateAction":\$1"ref":"myActionId"\$1 | 
| onSuccess | An action to run when current object succeeds. | Reference Object, e.g. "onSuccess":\$1"ref":"myActionId"\$1 | 
| parent | Parent of the current object from which slots will be inherited. | Reference Object, e.g. "parent":\$1"ref":"myBaseObjectId"\$1 | 
| preconditionTimeout | The period from start after which precondition is marked as failed if still not satisfied | Period | 
| reportProgressTimeout | Timeout for remote work successive calls to reportProgress. If set, then remote activities that do not report progress for the specified period may be considered stalled and so retried. | Period | 
| retryDelay | The timeout duration between two retry attempts. | Period | 
| scriptArgument | Argument to be passed to shell script | String | 
| stderr | The Amazon S3 path that receives redirected system error messages from the command. If you use the runsOn field, this must be an Amazon S3 path because of the transitory nature of the resource running your activity. However, if you specify the workerGroup field, a local file path is permitted. | String | 
| stdout | The Amazon S3 path that receives redirected output from the command. If you use the runsOn field, this must be an Amazon S3 path because of the transitory nature of the resource running your activity. However, if you specify the workerGroup field, a local file path is permitted. | String | 

 


****  

| Runtime Fields | Description | Slot Type | 
| --- | --- | --- | 
| @activeInstances | List of the currently scheduled active instance objects. | Reference Object, e.g. "activeInstances":\$1"ref":"myRunnableObjectId"\$1 | 
| @actualEndTime | Time when the execution of this object finished. | DateTime | 
| @actualStartTime | Time when the execution of this object started. | DateTime | 
| cancellationReason | The cancellationReason if this object was cancelled. | String | 
| @cascadeFailedOn | Description of the dependency chain the object failed on. | Reference Object, e.g. "cascadeFailedOn":\$1"ref":"myRunnableObjectId"\$1 | 
| emrStepLog | EMR step logs available only on EMR activity attempts | String | 
| errorId | The errorId if this object failed. | String | 
| errorMessage | The errorMessage if this object failed. | String | 
| errorStackTrace | The error stack trace if this object failed. | String | 
| hadoopJobLog | Hadoop job logs available on attempts for EMR-based activities. | String | 
| hostname | The host name of client that picked up the task attempt. | String | 
| node | The node for which this precondition is being performed | Reference Object, e.g. "node":\$1"ref":"myRunnableObjectId"\$1 | 
| reportProgressTime | Most recent time that remote activity reported progress. | DateTime | 
| @scheduledEndTime | Schedule end time for object | DateTime | 
| @scheduledStartTime | Schedule start time for object | DateTime | 
| @status | The status of this object. | String | 
| @version | Pipeline version the object was created with. | String | 
| @waitingOn | Description of list of dependencies this object is waiting on. | Reference Object, e.g. "waitingOn":\$1"ref":"myRunnableObjectId"\$1 | 

 


****  

| System Fields | Description | Slot Type | 
| --- | --- | --- | 
| @error | Error describing the ill-formed object | String | 
| @pipelineId | Id of the pipeline to which this object belongs to | String | 
| @sphere | The sphere of an object denotes its place in the lifecycle: Component Objects give rise to Instance Objects which execute Attempt Objects | String | 

## See Also
<a name="shellcommandprecondition-seealso"></a>
+ [ShellCommandActivity](dp-object-shellcommandactivity.md)
+ [Exists](dp-object-exists.md)