| NAnt  Help  Task Reference  <exec> | v0.85 | 
Executes a system command.
| Attribute | Type | Description | Required | 
|---|---|---|---|
| program | string | The program to execute without command arguments. | True | 
| append | bool | Gets or sets a value indicating whether output should be appended to the output file. The default is false. | False | 
| basedir | directory | The directory the program is in. | False | 
| commandline | string | The command-line arguments for the program. | False | 
| output | file | The file to which the standard output will be redirected. | False | 
| resultproperty | string |  The name of a property in which the exit code of the program should be stored. Only of interest if  If the exit code of the program is "-1000" then the program could not be started, or did not exit (in time). | False | 
| useruntimeengine | bool | Specifies whether the external program should be executed using a runtime engine, if configured. The default is false. | False | 
| workingdir | directory | The directory in which the command will be executed. | 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 | 
| timeout | int | The maximum amount of time the application is allowed to execute, expressed in milliseconds. Defaults to no time-out. | 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 | 
| Attribute | Type | Description | Required | 
|---|---|---|---|
| exename | string | The name of the executable that should be used to launch the external program. | False | 
| useruntimeengine | bool | Specifies whether the external program should be executed using a runtime engine, if configured. The default is false. | False | 
A set of environment variables.
Represents an option.
| Attribute | Type | Description | Required | 
|---|---|---|---|
| name | string | Name of the option. | True | 
| if | bool | Indicates if the option should be passed to the task. If true then the option will be passed; otherwise, skipped. The default is true. | False | 
| unless | bool | Indicates if the option should not be passed to the task. If false then the option will be passed; otherwise, skipped. The default is false. | False | 
| value | string | Value of the option. The default is a null reference (Nothing in Visual Basic). | False | 
Represents an environment variable.
| Attribute | Type | Description | Required | 
|---|---|---|---|
| name | string | The name of the environment variable. | True | 
| dir | directory | The value for a directory-based environment variable. NAnt will convert it to an absolute path. | False | 
| file | file | The value for a file-based environment variable. NAnt will convert it to an absolute filename. | False | 
| if | bool | Indicates if the environment variable should be passed to the external program. If true then the environment variable will be passed; otherwise, skipped. The default is true. | False | 
| path | <path> | The value for a PATH like environment variable. You can use :or;as path separators and NAnt will convert it to the platform's local conventions. | False | 
| unless | bool | Indicates if the environment variable should not be passed to the external program. If false then the environment variable will be passed; otherwise, skipped. The default is false. | False | 
| value | string | The literal value for the environment variable. | False | 
Represents a command-line argument.
| 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 | 
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" />
    Ping "nant.sourceforge.net".
<exec program="ping">
    <arg value="nant.sourceforge.net" />
</exec>
    
       Execute a java application using IKVM.NET that requires the Apache FOP jars, and a set of custom jars. 
      <path id="fop-classpath">
          <pathelement file="${fop.dist.dir}/build/fop.jar" />
          <pathelement file="${fop.dist.dir}/lib/xercesImpl-2.2.1.jar" />
          <pathelement file="${fop.dist.dir}/lib/avalon-framework-cvs-20020806.jar" />
          <pathelement file="${fop.dist.dir}/lib/batik.jar" />
      </path>
      <exec program="ikvm.exe" useruntimeengine="true">
          <arg value="-cp" />
          <arg>
              <path>
                  <pathelement dir="conf" />
                  <path refid="fop-classpath" />
                  <pathelement file="lib/mylib.jar" />
                  <pathelement file="lib/otherlib.zip" />
              </path>
          </arg>
          <arg value="org.me.MyProg" />
      </exec>
  
         Assuming the base directory of the build file is "c:\ikvm-test" and the value of the "fop.dist.dir" property is "c:\fop", then the value of the -cp argument that is passed toikvm.exe is "c:\ikvm-test\conf;c:\fop\build\fop.jar;conf;c:\fop\lib\xercesImpl-2.2.1.jar;c:\fop\lib\avalon-framework-cvs-20020806.jar;c:\fop\lib\batik.jar;c:\ikvm-test\lib\mylib.jar;c:\ikvm-test\lib\otherlib.zip" on a DOS-based system.