# mon-describe-alarm-history
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## Description
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Retrieves the history for the specified alarm. You can filter alarms by date range or item type. If you don't specify an alarm name, Amazon CloudWatch returns histories for all of your alarms.

**Note**  
Amazon CloudWatch retains the history of active and deleted alarms for two weeks.

## Syntax
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 ****mon-describe-alarm-history** [AlarmNames [*AlarmNames* ...]] [--end-date *value*] [--history-item-type *value*] [--start-date *value*] [Common Options] ** 

## Options
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| Name | Description | 
| --- | --- | 
|  `AlarmName` `AlarmNames`   |  The names of the alarms, separated by spaces. If you don't specify an alarm name, this command returns the histories of all your alarms. You can also set this value using `--alarm-name`. Type: Argument Valid values: Any string between 1 and 255 characters in length. Default: n/a Required: No  | 
|   `--end-date` `VALUE`   |  The end of the date range for history. Type: Date Valid values: Date in YYYY-MM-DD format. Default: The current date. Required: No  | 
|   `--history-item-type` `VALUE`   |  The type of history items to retrieve. By default, all types are returned. Type: Enumeration Valid values: ConfigurationUpdate, StateUpdate, or Action Default: All types are returned. Required: No  | 
|  `--start-date` `VALUE`   |  The start of the date range for history. By default it extends to all available history. Type: Date Valid values: Date in YYYY-MM-DD format. Default: All available history. Required: No  | 

## Common options
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| Name | Description | 
| --- | --- | 
|  `--aws-credential-file` `VALUE`   |  The location of the file with your AWS credentials. You can set this value using the environment variable `AWS_CREDENTIAL_FILE`. If you define the environment variable or you provide the path to the credential file, the file must exist or the request fails. All CloudWatch requests must be signed using your access key ID and secret access key. Type: String Valid values: A valid path to a file containing your access key ID and secret access key. Default: Uses the environment variable `AWS_CREDENTIAL_FILE`, if set.  | 
|  `-C, --ec2-cert-file-path` `VALUE`   |  The location of your EC2 certificate file for signing requests. You can use the environment variable `EC2_CERT` to specify this value. Type: String Valid values: A valid file path to the PEM file provided by Amazon EC2 or AWS Identity and Access Management. Default: Uses the environment variable `EC2_CERT`, if set.  | 
|   `--connection-timeout` `VALUE`   |  The connection timeout value, in seconds. Type: Integer Valid values: Any positive number. Default: 30  | 
|   `--delimiter` `VALUE`   |  The delimiter to use when displaying delimited (long) results. Type: String Valid values: Any string. Default: Comma (,)  | 
|   `--headers` ``   |  If you are displaying tabular or delimited results, include the column headers. If you are showing XML results, return the HTTP headers from the service request, if applicable. Type: Flag Valid values: When present, shows headers. Default: The `--headers` option is off by default.  | 
|   `-I, --access-key-id` `VALUE`   |  The access key ID that will be used, in conjunction with the secret key, to sign the request. This must be used in conjunction with --secret-key, otherwise the option is ignored. All requests to CloudWatch must be signed, otherwise the request is rejected. Type: String Valid values: A valid access key ID. Default: None  | 
|   `-K, --ec2-private-key-file-path` `VALUE`   |  The private key that will be used to sign the request. Using public/private keys causes the CLI to use SOAP. The request is signed with a public certificate and private key. This parameter must be used in conjunction with `EC2_CERT`, otherwise the value is ignored. The value of the environment variable `EC2_PRIVATE_KEY` will be used if it is set, and this option is not specified. This option is ignored if the environment variable `AWS_CREDENTIAL_FILE` is set, or `--aws-credentials-file` is used. All requests to CloudWatch must be signed, otherwise the request is rejected. Type: String Valid values: The path to a valid ASN.1 private key. Default: None  | 
|   `--region` `VALUE`   |  The region requests are directed to. You can use the environment variable `EC2_REGION` to specify the value. The region is used to create the URL used to call CloudWatch, and must be a valid Amazon Web Services (AWS) region. Type: String Valid values: Any AWS region, for example, us-east-1. Default: us-east-1, unless the `EC2_REGION` environment variable is set.  | 
|   `S, --secret-key` `VALUE`   |  The secret access key that will be used to sign the request, in conjunction with an access key ID. This parameter must be used in conjunction with `--access-key-id`, otherwise this option is ignored. Type: String Valid values: Your access key ID. Default: None  | 
|   `--show-empty-fields` ``   |  Shows empty fields using (nil) as a placeholder to indicate that this data was not requested. Type: Flag Valid values: None Default: Empty fields are not shown by default.  | 
|   `--show-request` ``   |  Displays the URL the CLI uses to call AWS. Type: Flag Valid values: None Default: false  | 
|   `--show-table, --show-long, --show-xml, --quiet` ``   |  Specifies how the results are displayed: in a table, delimited (long), XML, or no output (quiet). The `--show-table` display shows a subset of the data in fixed column-width form; `--show-long` shows all of the returned values delimited by a character; `--show-xml` is the raw return from the service; and `--quiet` suppresses all standard output. All options are mutually exclusive, with the priority `--show-table`, `--show-long`, `--show-xml`, and `--quiet`. Type: Flag Valid values: None Default: `--show-table`  | 
|   `-U, --url` `VALUE`   |  The URL used to contact CloudWatch. You can set this value using the environment variable `AWS_CLOUDWATCH_URL`. This value is used in conjunction with `--region` to create the expected URL. This option overrides the URL for the service call. Type: String Valid values: A valid HTTP or HTTPS URL. Default: Uses the value specified in `AWS_CLOUDWATCH_URL`, if set.  | 

## Output
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This command returns a table that contains the following:
+ ALARM - The alarm name.
+ TIMESTAMP - The timestamp.
+ TYPE - The type of event, one of ConfigurationUpdate, StateUpdate and Action.
+ SUMMARY - A human-readable summary of history event.
+ DATA - Detailed data about the event in machine-readable JSON format. This column appears only in the --show-long view.

The Amazon CloudWatch CLI displays errors on stderr.

## Examples
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### Example request
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This example describes all history items for the alarm my-alarm.

```
mon-describe-alarm-history--alarm-name my-alarm --headers
```

This is an example output of this command.

```
ALARM     TIMESTAMP                 TYPE                 SUMMARY
my-alarm  2013-05-07T18:46:16.121Z  Action               Published a notification to arn:aws:sns:...
my-alarm  2013-05-07T18:46:16.118Z  StateUpdate          Alarm updated from INSUFFICIENT_DATA to OK
my-alarm  2013-05-07T18:46:07.362Z  ConfigurationUpdate  Alarm "my-alarm" created
```

## Related topics
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### Download
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+ [Set up the command line interface](SetupCLI.md)

### Related action
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+ [DescribeAlarmHistory](http://docs.aws.amazon.com/AmazonCloudWatch/latest/APIReference/API_DescribeAlarmHistory.html)

### Related commands
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+  [mon-describe-alarms](cli-mon-describe-alarms.md) 
+  [mon-describe-alarms-for-metric](cli-mon-describe-alarms-for-metric.md)