cgtop: allow user to force looping behavior even in non-TTY mode

src/cgtop/cgtop.c

@@ -60,7 +60,7 @@ typedef struct Group {
 } Group;
 
 static unsigned arg_depth = 3;
-static unsigned arg_iterations = 0;
+static unsigned arg_iterations = (unsigned)-1;
 static bool arg_batch = false;
 static bool arg_raw = false;
 static usec_t arg_delay = 1*USEC_PER_SEC;
@@ -715,8 +715,8 @@ int main(int argc, char *argv[]) {
 
         signal(SIGWINCH, columns_lines_cache_reset);
 
-        if (!on_tty())
-                arg_iterations = 1;
+        if (arg_iterations == (unsigned)-1)
+                arg_iterations = on_tty() ? 0 : 1;
 
         while (!quit) {
                 Hashmap *c;