getpid.clj

(ns getpid
  (:import [jnr.ffi.types pid_t]
           [jnr.ffi LibraryLoader]))

;; see https://github.com/jnr/jnr-ffi-examples/blob/master/getpid/src/main/java/getpid/Getpid.java
;; using dependency: [com.github.jnr/jnr-ffi "2.0.9"]

;; public interface LibC  {
;;   public @pid_t long getpid();
;;   public @pid_t long getppid();
;; }

(definterface LibC
  (^{pid_t true :tag long} getpid [])
  (^{pid_t true :tag long} getppid []))

;; LibC libc = LibraryLoader.create(LibC.class).load("c");
;; System.out.println("pid=" + libc.getpid() + " parent pid=" + libc.getppid());

(defn -main [& args]
  (let [libc (.load (LibraryLoader/create LibC) "c")
        pid (.getpid libc)
        ppid (.getppid libc)]
    (println (format "found pid: %d, ppid: %d" pid ppid))))