$ cat hup.scm
(cond-expand
 (chicken-4
  (use posix))
 (chicken-5
  (import
   (chicken base)
   (chicken process signal)
   (chicken process-context))))

(define param (make-parameter 42))

(define conf-file (car (command-line-arguments)))

; (load conf-file)

(set-signal-handler!
 signal/hup
 (lambda (signum)
   (print "reloading conf file")
   (load conf-file)))

(let loop ()
  (print (param))
  (sleep 1)
  (loop))


$ cat conf.scm
(param 4)


;;; Case 1: `(load conf-file)` in the toplevel commented out
;;; Steps:
;;;  1. run hup.scm
;;;  2. go to another terminal and kill it with signal 1

$ ~/local/chicken-4.13.0/bin/csi -s hup.scm conf.scm
42
42
42
reloading conf file
4
4
4

$ ~/local/chicken-5.1.0/bin/csi -s hup.scm conf.scm
42
42
42
reloading conf file
42
42
42


;;; Case 2: `(load conf-file)` in the toplevel uncommented
;;; Steps:
;;;  1. run hup.scm
;;;  2. go to another terminal change param in conf.scm and kill csi
;;;     with signal 1
$ ~/local/chicken-4.13.0/bin/csi -s hup.scm conf.scm
4
4
4
reloading conf file
10
10
10

$ ~/local/chicken-5.1.0/bin/csi -s hup.scm conf.scm
10
10
10
reloading conf file
12
12
12