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h2. Exec component
*Available in Camel 2.3*

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

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 theexecution executable has has not finishedcompleted 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 output of the executableits output. If no {{outFile}} is set, the standard output (stdout) of the executable will be consideredused as outputinstead. |
| {{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/]., Itwhich adds a shutdown hook for every executed command.|
| {{useStderrOnEmptyStdout}} | {{false}} | A boolean whichindicating dictatesthat when {{stdinstdout}} is empty, itthis shouldcomponent fallback and use {{stderr}} in will populate the Camel Message Body with {{stderr}}. This optionbehavior is defaultdisabled ({{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 the {{executable}} in the URI.|
|{{ExecBinding.EXEC_COMMAND_ARGS}}|{{java.util.List<String>}}|{{in}}|TheCommand-line arguments to ofpass to the executed executableprocess. 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 of the executable. 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. Typically notNon-zero exit values typically indicatesindicate 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 the {{stdinstdout}} is empty, should we fallback and usethis component will populate the Camel Message Body with {{stderr}} as the body of the Camel Message. ByThis defaultbehavior thisis optiondisabled is ({{false}}) by default. |
{div}

h3. Message body
If the {{inExec}} messagecomponent body, that that thereceives an {{Execin}} message componentbody receives,that is convertible to {{java.io.InputStream}}, it is used to feed input ofto the executable via its stdin. After the 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. TheThis 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 usedspecified (in the endpoint is configuredvia with {{outFile}}, or the theremessage headers isvia {{ExecBinding.EXEC_COMMAND_OUT_FILE}} header), theconverters converterswill return the content of the out file. If no out file is used, then thethis converterscomponent will useconvert the stdout of the process for conversion to the target type. For more details, exampleplease 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 into the standartstandard 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 theits ant 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}

{include:Endpoint See Also}