Java ProcessBuilder在PATH中找不到文件

Question

I try to run curl from my java application. Here is my code:

ProcessBuilder pb = new ProcessBuilder("curl",
                    "-T",
                    "\"" + tmp_dir + "client-" + node_id + ".war\"",
                    "\"" + tomcat_url + "/deploy?path=/client" + node_id + "&update=true\"");
Process p = pb.start();

yet, it gives the exception:

java.io.IOException: Cannot run program "curl": CreateProcess error=2, The system cannot find the file specified

curl is in my System PATH and user PATH, and when I run curl from cmd it works perfectly:

Also, when I give ProcessBuilder absolute path to curl executable, it works, but I don't want to do that since my code should work with curl whatver directory it's installed into

What am I doing wrong?

Answer 1

It is the shell (or command processor) that locates a file among the directories defined in the PATH variable.

Simply starting a subprocess with a path to a command and a list of arguments does not go through the shell, unless you explicitly code it to do so.

If you can't offload the exact position of curl into some system property, you may have to interpret PATH and try all directories and then call with the full pathname.

public static Path findAbsolutePath( String curl ){
  String path = System.getenv( "PATH" );
  String[] dirs = path.split( ";" );
  for( String dir: dirs ){
    Path toCurl = Paths.get( dir, curl );
    File curlFile = new File( toCurl.toString() );
    if( curlFile.canExecute() ) return toCurl;
  }
  return null;
}

Or call the command processor.

Answer 2

ProcessBuilder#ProcessBuilder(String... command) javadoc:

It is not checked whether command corresponds to a valid operating system command.

So you need to build the absolute path to curl in the string you pass to the constructor.

Answer 3

I am posting this answer because i was not able to fix this problem with all the existing answer:

This is one of the answers for any beginner.(mostly combination of all the existing answer).

1. In the Windows machine make sure curl is installed. (follow the google to install)
2. Make sure you add the curl bin path to environment system variable
3. Restart the machine. (Important!. Because i spent lot of time because the processBuilder was using the PATH that was not having the CURL in it. Restarting fixed it) This is reason for the original error in the question.
4. You can use System.getenv( "PATH" ) to verify on the code.

Addon : If you are using POST , then make sure the post payload is escaped when running through WINDOWS. and NOT escaped when running through MAC. I really do not know the problem but it took lot time to debug. Escape in the sense: " with \\" .