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h2. Exec component
*Available in Camel 2.3*

The {{exec}} component can be used to execute system commands. 

h3. Dependencies
Maven users need to add the following dependency to their {{pom.xml}}
{code:xml}
<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-exec</artifactId>
  <version>${camel-version}</version>
</dependency>
{code}
where {{$\{camel-version\}}} must be replaced by the actual version of Camel (2.3.0 or higher). 

h3. URI format
{code:xml}
exec://executable[?options]
{code}
where {{executable}} is the name, or file path, of the system command that will be executed. If executable name is used (e.g. {{exec:java}}), the executable must in the system path.

h3. URI options

{div:class=confluenceTableSmall}
|| Name || Default value || Description ||
| {{args}} | {{null}} | The arguments of the executable. The arguments may be one or many
whitespace-separated tokens, that can be quoted with {{"}} - e.g. {{args="arg 1" arg2}} will use two arguments {{arg 1}} and {{arg2}}. To include the quotes use {{""}} - e.g. {{args=""arg 1"" arg2}} will use the arguments {{"arg 1"}} and {{arg2}}.|
| {{workingDir}} | {{null}} |The directory in which the command should be executed. If {{null}}, the working directory of the current process will be used.|
| {{timeout}} | {{Long.MAX_VALUE}}|The timeout, in milliseconds, after which the executable should be terminated. If execution has not completed within the timeout, the component will send a termination request.|
| {{outFile}} | {{null}} |The name of a file, created by the executable, that should be considered as its output. If no {{outFile}} is set, the standard output (stdout) of the executable will be used instead. |
| {{binding}} | a {{DefaultExecBinding}} instance | A reference to a {{org.apache.commons.exec.ExecBinding}} in the [Registry|http://camel.apache.org/registry.html].|
| {{commandExecutor}} |a {{DefaultCommandExecutor}} instance | A reference to a {{org.apache.commons.exec.ExecCommandExecutor}} in the [Registry|http://camel.apache.org/registry.html] that customizes the command execution. The default command executor utilizes the [commons-exec library|http://commons.apache.org/exec/], which adds a shutdown hook for every executed command.|
| {{useStderrOnEmptyStdout}} | {{false}} | A boolean indicating that when {{stdout}} is empty, this component will populate the Camel Message Body with {{stderr}}. This behavior is disabled ({{false}}) by default. |
{div}

h3. Message headers
The supported headers are defined in {{org.apache.camel.component.exec.ExecBinding}}.
{div:class=confluenceTableSmall}
||Name||Type||Message ||Description||
|{{ExecBinding.EXEC_COMMAND_EXECUTABLE}}|{{String}}|{{in}}| The name of the system command that will be executed. Overrides {{executable}} in the URI.|
|{{ExecBinding.EXEC_COMMAND_ARGS}}|{{java.util.List<String>}}|{{in}}|Command-line arguments to pass to the executed process. The arguments are used literally - no quoting is applied. Overrides any existing {{args}} in the URI.|
|{{ExecBinding.EXEC_COMMAND_ARGS}}|{{String}}|{{in}}| *Camel 2.5:* The arguments of the executable as a Single string where each argument is whitespace separated (see {{args}} in URI option). The arguments are used literally, no quoting is applied. Overrides any existing {{args}} in the URI.|
|{{ExecBinding.EXEC_COMMAND_OUT_FILE}}|{{String}}|{{in}}|The name of a file, created by the executable, that should be considered as its output. Overrides any existing {{outFile}} in the URI.|
|{{ExecBinding.EXEC_COMMAND_TIMEOUT}}|{{long}}|{{in}}|The timeout, in milliseconds, after which the executable should be terminated. Overrides any existing {{timeout}} in the URI.|
|{{ExecBinding.EXEC_COMMAND_WORKING_DIR}}|{{String}}|{{in}}|The directory in which the command should be executed. Overrides any existing {{workingDir}} in the URI.|
|{{ExecBinding.EXEC_EXIT_VALUE}}|{{int}}|{{out}}|The value of this header is the _exit value_ of the executable. Non-zero exit values typically indicate abnormal termination. Note that the exit value is OS-dependent.|
|{{ExecBinding.EXEC_STDERR}}|{{java.io.InputStream}}|{{out}}|The value of this header points to the standard error stream (stderr) of the executable. If no stderr is written, the value is {{null}}.|
|{{ExecBinding.EXEC_USE_STDERR_ON_EMPTY_STDOUT}}|{{boolean}}|{{in}}| Indicates that when {{stdout}} is empty, this component will populate the Camel Message Body with {{stderr}}. This behavior is disabled ({{false}}) by default. |
{div}

h3. Message body
If the {{Exec}} component receives an {{in}} message body that is convertible to {{java.io.InputStream}}, it is used to feed input to the executable via its stdin. After execution, [the message body|http://camel.apache.org/exchange.html] is the result of the execution,- that is, an {{org.apache.camel.components.exec.ExecResult}} instance containing the stdout, stderr, exit value, and out file. This component supports the following {{ExecResult}} [type converters|http://camel.apache.org/type-converter.html] for convenience:

{div:class=confluenceTableSmall}
||From||To||
|{{ExecResult}} | {{java.io.InputStream}}| 
|{{ExecResult}} | {{String}}| 
|{{ExecResult}} | {{byte \[\]}}|
|{{ExecResult}} | {{org.w3c.dom.Document}}|
If an out file is specified (in the endpoint via {{outFile}} or the message headers via {{ExecBinding.EXEC_COMMAND_OUT_FILE}}), converters will return the content of the out file. If no out file is used, then this component will convert the stdout of the process to the target type. For more details, please refer to the [usage examples|#usage] below.
{div}

{anchor:usage}
h3. Usage examples
h4. Executing word count (Linux)
The example below executes {{wc}} (word count, Linux) to count the words in file {{/usr/share/dict/words}}. The word count (output) is written to the standard output stream of {{wc}}.
{code:java}
from("direct:exec")
.to("exec:wc?args=--words /usr/share/dict/words")
.process(new Processor() {
     public void process(Exchange exchange) throws Exception {
       // By default, the body is ExecResult instance
       assertIsInstanceOf(ExecResult.class, exchange.getIn().getBody());
       // Use the Camel Exec String type converter to convert the ExecResult to String
       // In this case, the stdout is considered as output
       String wordCountOutput = exchange.getIn().getBody(String.class);
       // do something with the word count
     }
});
{code} 

h4. Executing {{java}}
The example below executes {{java}} with 2 arguments: {{-server}} and {{-version}}, provided that {{java}} is in the system path. 
{code}
from("direct:exec")
.to("exec:java?args=-server -version")
{code}
The example below executes {{java}} in {{c:\temp}} with 3 arguments: {{-server}}, {{-version}} and the sytem property {{user.name}}.
{code}
from("direct:exec")
.to("exec:c:/program files/jdk/bin/java?args=-server -version -Duser.name=Camel&workingDir=c:/temp")
{code}
h4. Executing Ant scripts
The following example executes [Apache Ant|http://ant.apache.org/] (Windows only) with the build file {{CamelExecBuildFile.xml}}, provided that {{ant.bat}} is in the system path, and that {{CamelExecBuildFile.xml}} is in the current directory.
{code}
from("direct:exec")
.to("exec:ant.bat?args=-f CamelExecBuildFile.xml")
{code}
In the next example, the {{ant.bat}} command redirects its output to {{CamelExecOutFile.txt}} with {{-l}}. The file {{CamelExecOutFile.txt}} is used as the out file with {{outFile=CamelExecOutFile.txt}}. The example assumes that {{ant.bat}} is in the system path, and that {{CamelExecBuildFile.xml}} is in the current directory.
{code:java}
from("direct:exec")
.to("exec:ant.bat?args=-f CamelExecBuildFile.xml -l CamelExecOutFile.txt&outFile=CamelExecOutFile.txt")
.process(new Processor() {
     public void process(Exchange exchange) throws Exception {
        InputStream outFile = exchange.getIn().getBody(InputStream.class);
        assertIsInstanceOf(InputStream.class, outFile);
        // do something with the out file here
     }
  });
{code}
h4. Executing {{echo}} (Windows)
Commands such as {{echo}} and {{dir}} can be executed only with the command interpreter of the operating system. This example shows how to execute such a command - {{echo}} - in Windows.
{code:java}
from("direct:exec").to("exec:cmd?args=/C echo echoString")
{code}

{include:Endpoint See Also}