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Tooling Intermediate

Runtime.exec(String) to ProcessBuilder arguments

Launch processes with an explicit argument list and ProcessBuilder configuration.

Tooling Security

Code Comparison

✕ Command string

Process process = Runtime.getRuntime()
        .exec("git show " + revision);

✓ ProcessBuilder

Process process = new ProcessBuilder(
        "git", "show", revision)
        .redirectErrorStream(true)
        .start();

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Why the modern way wins

🎯

Exact arguments

Each process argument remains a distinct value without command-string tokenization.

🎛

Explicit configuration

Environment, directory, redirects, and error handling are configured together.

🛡

Safer boundaries

Avoids constructing a shell-like command string from dynamic values.

Old Approach

Runtime.exec(String)

Modern Approach

ProcessBuilder

Since JDK

Difficulty

Intermediate

JDK Support

Runtime.exec(String) to ProcessBuilder arguments

Available

Widely available since JDK 5 (September 2004)

How it works

Runtime.exec(String) applies Java's command-string tokenization, which is easy to misunderstand when arguments contain spaces or quoting. ProcessBuilder accepts program arguments as distinct values and exposes the working directory, environment, input/output redirects, and error-stream policy explicitly. It does not invoke a shell unless the application deliberately launches one.

Modern Process API

Java 8

Process p = Runtime.getRuntime()
    .exec("ls -la");
int code = p.waitFor();
// no way to get PID
// no easy process info

Java 9+

ProcessHandle ph =
    ProcessHandle.current();
long pid = ph.pid();
ph.info().command()
    .ifPresent(IO::println);
ph.children().forEach(
    c -> IO.println(c.pid()));

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JDK 9+ →

I/O Beginner

InputStream.transferTo()

Java 8

byte[] buf = new byte[8192];
int n;
while ((n = input.read(buf)) != -1) {
    output.write(buf, 0, n);
}

Java 9+

input.transferTo(output);

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JDK 9+ →

Security Advanced

SecurityManager checks to explicit authorization

JDK 23 and earlier

SecurityManager manager = System.getSecurityManager();
if (manager != null) {
    manager.checkRead(path.toString());
}
return Files.readString(path);

JDK 24+

// Untrusted users must not be able to modify this tree
Path root = allowedRoot.toRealPath();
Path resolved = root.resolve(requested)
    .normalize()
    .toRealPath();
if (!resolved.startsWith(root)) {
    throw new SecurityException(
        "Path is outside the allowed root");
}
return Files.readString(resolved);

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JDK 24+ →