add process killing example

Author: perazz

example/system/CMakeLists.txt

@@ -1,3 +1,4 @@
 ADD_EXAMPLE(process_1)
 ADD_EXAMPLE(process_2)
 ADD_EXAMPLE(process_3)
+ADD_EXAMPLE(process_4)

example/system/example_process_4.f90

@@ -0,0 +1,34 @@
+! Process example 4: Kill a running process
+program example_process_kill
+    use stdlib_system, only: process_type, run, is_running, kill, elapsed, has_win32, sleep
+    implicit none
+    type(process_type) :: process
+    logical :: running, success
+
+    print *, "Starting a long-running process..."
+    if (has_win32()) then
+        process = run("ping -n 10 127.0.0.1", wait=.false.)
+    else
+        process = run("ping -c 10 127.0.0.1", wait=.false.)
+    endif
+
+    ! Verify the process is running
+    running = is_running(process)
+    print *, "Process running:", running
+
+    ! Wait a bit before killing the process
+    call sleep(millisec=1250)  ! Portable subroutine for sleeping
+
+    print *, "Killing the process..."
+    call kill(process, success)
+
+    if (success) then
+        print *, "Process killed successfully."
+    else
+        print *, "Failed to kill the process."
+    endif
+
+    ! Verify the process is no longer running
+    running = is_running(process)
+    print *, "Process running after kill:", running
+end program example_process_kill