Running unix command using java shows error

Question

Hi All,
I am trying to run UNIX move command using Java exec method but its throwing error, unable to rename. Here below is the code i am trying to run to move all files from one directory to another directory. source and destination directory exists.
public class Demo
    public static void main(String args[])
        try
            Runtime rt = Runtime.getRuntime();
            Process proc = rt.exec("mv /home/demo1/* /home/demo2");
            int exitVal = proc.waitFor();
            System.out.println("Process exitValue: " + exitVal);
        } catch (Throwable t)
            t.printStackTrace();
}if i give "mv /home/demo1 /home/demo2" in exec method, its working, with * character its giving problem.
Please help me in resolving the problem.
Thank you

Answer 1

Characters like *, >, &, |, etc. are interpreted by the command shell--that is by the bash, zsh, etc. programs. When you execute a command with ProcessBuilder or Runtime.exec, you're not going through one of those shells, so their interpretation of those characters is not available.
In your code, the character * is being delivered directly to the mv command (which doesn't think * is anything special), as opposed to being turned into a list of files and directories as it would be when it's interpreted by the shell. The mv command doesn't know anything about the * character being special.
If you want to have those shell interpretations, you need to execute the command through a shell. One example is like so, but a) you'll want to read up on the methods in exec() that take arrays of String, and b) you'll want to read up on ProcessBuilder, and c) you'll need to check your shell's man pages to see the exact syntax and arguments.
runtime.exec("/bin/bash -c 'mv x/* y'");