Running Bash commands in Java

Question

I have the following class. It allows me to execute commands through java.

public class ExecuteShellCommand {

public String executeCommand(String command) {         


        

Answer 1

You can form one complex bash command that does everything: "ls; cd bin; ls". To make this work you need to explicitly invoke bash. This approach should give you all the power of the bash command line (quote handling, $ expansion, pipes, etc.).

/**
 * Execute a bash command. We can handle complex bash commands including
 * multiple executions (; | && ||), quotes, expansions ($), escapes (\), e.g.:
 *     "cd /abc/def; mv ghi 'older ghi '$(whoami)"
 * @param command
 * @return true if bash got started, but your command may have failed.
 */
public static boolean executeBashCommand(String command) {
    boolean success = false;
    System.out.println("Executing BASH command:\n   " + command);
    Runtime r = Runtime.getRuntime();
    // Use bash -c so we can handle things like multi commands separated by ; and
    // things like quotes, $, |, and \. My tests show that command comes as
    // one argument to bash, so we do not need to quote it to make it one thing.
    // Also, exec may object if it does not have an executable file as the first thing,
    // so having bash here makes it happy provided bash is installed and in path.
    String[] commands = {"bash", "-c", command};
    try {
        Process p = r.exec(commands);

        p.waitFor();
        BufferedReader b = new BufferedReader(new InputStreamReader(p.getInputStream()));
        String line = "";

        while ((line = b.readLine()) != null) {
            System.out.println(line);
        }

        b.close();
        success = true;
    } catch (Exception e) {
        System.err.println("Failed to execute bash with command: " + command);
        e.printStackTrace();
    }
    return success;
}