====== Execute OS Command or External Process ======

PL/HQL allows you to execute an OS command or external process from a PL/HQL script:

**Syntax**:

! command:

<code language="sql">
!cmd [arguments];
</code>

HOST statement:

<code language="sql">
HOST string_expr
</code>

**Parameters:**

| **Parameter** | **Description** |
| cmd | Any OS command or process |
| arguments | Optional argument list | 
| string_expr | Command line for HOST statement |

**Notes**:

  * Blank characters are allowed between ! and cmd
  * The ! command must be terminated by a semicolon (;)

**Example:**

Using ! command:

<code language="sql">
!echo Hello, world;
</code> 

Using HOST statement:

<code language="sql">
HOST 'echo Hello, world';
</code>

**Compatibility**: Apache Hive (! command), Oracle (HOST statement).

**Version**: PL/HQL 0.01