Inlab Scheme offers a group of expressions and procedures which interface directly to the Standard C-Library of the host operating system (Linux or macOS). In the case that you are missing a specific functionality in this area, just let us know.
(argument-vector) returns the current Unix argv of the interpreter invocation as a vector of strings.
 (argument-vector) #("./scheme") 
(argv) returns the current Unix argv of the interpreter invocation as a list of strings.
argv is implemented as follows:
 (argv) ("./scheme")  (pp argv) (lambda () (vector->list (argument-vector))) ok 
(rand) returns a pseudo random signed integer invoking rand().
 (rand) 727386614 
(sleep <seconds>) interfaces the sleep() C-Library system call. Inlab Scheme suspends its execution the supplied number of seconds. The invocation (sleep 0) returns immediately, passing a negative value is not allowed.
 (sleep 2) ok  (sleep 0) ok  (sleep -1) ERROR! message : invalid negative value irritant : #<primitive-procedure sleep> expression: -1 continue : possible, continue with value as value from primitive Error (? for help) >>
(system <command>) invokes the system() call passing the string as a command to be executed by the sh command interpreter. The exit code of this execution is returned as an integer.
 (system "echo hello") hello 0  (system "notfound") sh: notfound: command not found 127  (system "exit 3") 3 
(usleep <seconds>) interfaces the usleep() C-Library system call. Inlab Scheme suspends its execution the supplied number of microseconds. The invocation (usleep 0) returns immediately, passing a negative value is not allowed.
 (usleep 2000) ok  (usleep 2000000) ok