Exec

Exec component

Available in Camel 2.3

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

Dependencies

Maven users need to add the following dependency to their pom.xml

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-exec</artifactId>
  <version>${camel-version}</version>
</dependency>

where ${camel-version} must be replaced by the actual version of Camel (2.3.0 or higher).

URI format

exec://executable[?options]

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.

URI options

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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 the executable has has not finished 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 executable. If no `outFile` is set, the standard output (stdout) of the executable will be considered as output.
`binding`	a `DefaultExecBinding` instance	A reference to a `org.apache.commons.exec.ExecBinding` in the Registry.
`commandExecutor`	a `DefaultCommandExecutor` instance	A reference to a `org.apache.commons.exec.ExecCommandExecutor` in the Registry, that customizes the command execution. The default command executor utilizes the commons-exec library. It adds a shutdown hook for every executed command.
`useStderrOnEmptyStdout`	`false`	A boolean which dictates when `stdin` is empty, it should fallback and use `stderr` in the Camel Message Body. This option is default `false`.

Message headers

The supported headers are defined in org.apache.camel.component.exec.ExecBinding.

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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`	The arguments of the executable. The arguments are used literally, no quoting is applied. Overrides 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 output of the executable. Overrides existing `outFile` in the URI.
`ExecBinding.EXEC_COMMAND_TIMEOUT`	`long`	`in`	The timeout, in milliseconds, after which the executable should be terminated. Overrides existing `timeout` in the URI.
`ExecBinding.EXEC_COMMAND_WORKING_DIR`	`String`	`in`	The directory in which the command should be executed. Overrides existing `workingDir` in the URI.
`ExecBinding.EXEC_EXIT_VALUE`	`int`	`out`	The value of this header is the exit value of the executable. Typically not-zero exit values indicates 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 when the `stdin` is empty, should we fallback and use `stderr` as the body of the Camel Message. By default this option is `false`.

Message body

If the in message body, that that the Exec component receives, is convertible to java.io.InputStream, it is used to feed input of the executable via its stdin. After the execution, the message body is the result of the execution, that is org.apache.camel.components.exec.ExecResult instance containing the stdout, stderr, exit value and out file. The component supports the following ExecResult type converters for convenience:

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From	To
`ExecResult`	`java.io.InputStream`
`ExecResult`	`String`
`ExecResult`	`byte []`
`ExecResult`	`org.w3c.dom.Document`

If out file is used (the endpoint is configured with outFile, or there is ExecBinding.EXEC_COMMAND_OUT_FILE header) the converters return the content of the out file. If no out file is used, then the converters will use the stdout of the process for conversion to the target type. For example refer to the usage examples.

Usage examples

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 in the standart output stream of wc.

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
     }
});

Executing java

The example below executes java with 2 arguments: -server and -version, provided that java is in the system path.

from("direct:exec")
.to("exec:java?args=-server -version")

The example below executes java in c:/temp with 3 arguments: -server, -version and the sytem property user.name.

from("direct:exec")
.to("exec:c:/program files/jdk/bin/java?args=-server -version -Duser.name=Camel&workingDir=c:/temp")

Executing Ant scripts

The following example executes Apache Ant (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.

from("direct:exec")
.to(exec:ant.bat?args=-f CamelExecBuildFile.xml")

In the next example, the ant.bat command, redirects the ant output to CamelExecOutFile.txt with -l. The file CamelExecOutFile.txt is used as 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.

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
     }
  });

Child pages

Exec component

Dependencies

URI format

URI options

Message headers

Message body

Usage examples

Executing word count (Linux)

Executing java

Executing Ant scripts

See Also