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
| 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.
| 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:
| 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 {
assertIsInstanceOf(ExecResult.class, exchange.getIn().getBody());
String wordCountOutput = exchange.getIn().getBody(String.class);
}
});
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);
}
});
See Also
