Resolving Output Redirection Issue with Runtime's exec() Method

In Java, utilizing Runtime.getRuntime().exec() to run a command allows for capturing the process's output and error streams. However, in cases where output redirection is desired, this method alone may prove ineffective.

The Problem: Output Not Being Redirected

When employing Runtime.getRuntime().exec() with commands that feature output redirection, such as > , the redirect operation might fail. The target file may not be created, and the output stream remains unredirected.

The Solution: Employing ProcessBuilder

To successfully redirect output, consider utilizing ProcessBuilder instead. This class offers a more granular approach to process creation, enabling the specification of output and error stream redirection.

Here's how to use ProcessBuilder for output redirection:

ProcessBuilder builder = new ProcessBuilder("sh", "somescript.sh");
builder.redirectOutput(new File("out.txt"));
builder.redirectError(new File("out.txt"));
Process p = builder.start(); // may throw IOException

By using ProcessBuilder, you can redirect both the standard output and standard error streams to the desired file, ensuring that the output from the command is captured.