Java Runtime exec() with mysqldump

Question

I'm a little curious about the behaviour of Runtime's exec() method when I run mysqldump. I'm running the following command:

mysqldump --user=root --hex-blob [database name] -r [path to sql file]

What I'm wondering is, where does Runtime search for the program mysqldump.exe?

I see that some people supply the whole file path to mysqldump.exe when executing it using Runtime. Why is this?

The reason why I'm curious is because I have two scenarios:

1. On one windows machine, if I open run and type "cmd" it will open a command window with the default location C:/. Running the mysqldump command on this machine works.
2. On another windows machine, if I open run and type "cmd" it will open a command window with the default location H:/. Running the mysqldump command on this machine fails. Java's Runtime cannot find the file mysqldump.exe.

Is it possible that the two windows machines have different default drives and if I don't supply the full path to mysqldump.exe, the system will look in the default driver?

Thanks in advance!

Answer 1

As mentioned in the documentation :

Starting an operating system process is highly system-dependent . Among the many things that can go wrong are:

• The operating system program file was not found.
• Access to the program file was denied
• The working directory does not exist.

What I would suggest is starting with a ProcessBuilder , something like:

 ProcessBuilder pb = new ProcessBuilder("mysqldump ...");
 Map<String, String> env = pb.environment();
 env.put("PATH", env.get("PATH") + ";Path/to/mysqldump");
 try {
    Process process = pb.start();
    //some code
 } catch(IOException e){
 }

This way you ensure the environment variable is correctly set.