# ExternalProgramBase

[This is preliminary documentation and subject to change.]

Provides the abstract base class for tasks that execute external applications.

When a ProgramLocationAttribute is applied to the deriving class and `exename` does not return an absolute path, then the program to execute will first be searched for in the location specified by `LocationType`.

If the program does not exist in that location, then the list of tool paths of the current target framework will be scanned in the order in which they are defined in the NAnt configuration file.

### Parameters

Attribute | Type | Description | Required
--- | --- | --- | ---
timeout | int | The maximum amount of time the application is allowed to execute, expressed in milliseconds. Defaults to no time-out. | False
failonerror | bool | Determines if task failure stops the build, or is just reported. The default is true. | False
if | bool | If true then the task will be executed; otherwise, skipped. The default is true. | False
unless | bool | Opposite of `if`. If false then the task will be executed; otherwise, skipped. The default is false. | False
verbose | bool | Determines whether the task should report detailed build log messages. The default is false. | False

### Framework-configurable parameters

Attribute | Type | Description | Required
--- | --- | --- | ---
exename | string | The name of the executable that should be used to launch the external program. | False
managed | ManagedExecution | Specifies whether the external program should be treated as a managed application, possibly forcing it to be executed under the currently targeted version of the CLR. | False
useruntimeengine | bool | Deprecated. Specifies whether the external program is a managed application which should be executed using a runtime engine, if configured. The default is false. | False

### Nested Elements:

#### <arg>

The command-line arguments for the external program.

Represents a command-line argument.

When passed to an external application, the argument will be quoted when appropriate. This does not apply to the `line` parameter, which is always passed as is.

### Parameters

Attribute | Type | Description | Required
--- | --- | --- | ---
dir | directory | The value for a directory-based command-line argument; will be replaced with the absolute path of the directory. | False
file | file | The name of a file as a single command-line argument; will be replaced with the absolute filename of the file. | False
if | bool | Indicates if the argument should be passed to the external program. If true then the argument will be passed; otherwise, skipped. The default is true. | False
line | string | List of command-line arguments; will be passed to the executable as is. | False
path | <path> | The value for a PATH-like command-line argument; you can use `:` or `;` as path separators and NAnt will convert it to the platform's local conventions, while resolving references to environment variables. | False
unless | bool | Indicates if the argument should not be passed to the external program. If false then the argument will be passed; otherwise, skipped. The default is false. | False
value | string | A single command-line argument; can contain space characters. | False

### Nested Elements:

#### <path>

Sets a single command-line argument and treats it like a PATH - ensures the right separator for the local platform is used.

#### </path>

### Examples

- A single command-line argument containing a space character.

      <arg value="-l -a" />

- Two separate command-line arguments.

      <arg line="-l -a" />

- A single command-line argument with the value `\dir;\dir2;\dir3` on DOS-based systems and `/dir:/dir2:/dir3` on Unix-like systems.

      <arg path="/dir;/dir2:\dir3" />

#### </arg>

### Requirements

Assembly: NAnt.Core (0.91.3881.0)