Calling Unix command from Java

How do I execute the Unix grep program to search for patt开发者_Go百科erns in a set of files by calling that command from inside a Java program?

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You can use Runtime.exec

public Process exec(String[] cmdarray,
                    String[] envp,
                    File dir)
                    throws IOException

Executes the specified command and arguments in a separate process with the specified environment and working directory.

EDIT: As Joachim and andypandy point out, ProcessBuilder has a more flexible interface, and if you're running on JDK7 or later provides support for setting up sub-process file descriptors.

Starting a new process which uses the default working directory and environment is easy:

 Process p = new ProcessBuilder("myCommand", "myArg").start();

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Check out the javadoc for java.lang.Runtime#exec and java.lang.ProcessBuilder.