return !memcmp(str, pfx, strlen(pfx));
 }
 
-void print_hex(void *arg, unsigned int n, const char *sep)
+void fprint_hex(FILE *f, void *arg, unsigned int n, const char *sep)
 {
        unsigned char *data = arg;
        unsigned int i;
                if (!i)
                        /* nothing */;
                else if (!(i % 16))
-                       printf("\n");
+                       fprintf(f, "\n");
                else if (!(i % 8))
-                       printf("  ");
+                       fprintf(f, "  ");
                else
                        pfx = sep;
 
-               printf("%s%02hhx", i ? pfx : "", data[i]);
+               fprintf(f, "%s%02hhx", i ? pfx : "", data[i]);
        }
 }
 
 
                        !break_names;
 
                printf("key:%c", break_names ? '\n' : ' ');
-               print_hex(key, info->key_size, " ");
+               fprint_hex(stdout, key, info->key_size, " ");
 
                printf(single_line ? "  " : "\n");
 
                printf("value:%c", break_names ? '\n' : ' ');
-               print_hex(value, info->value_size, " ");
+               fprint_hex(stdout, value, info->value_size, " ");
 
                printf("\n");
        } else {
                n = get_possible_cpus();
 
                printf("key:\n");
-               print_hex(key, info->key_size, " ");
+               fprint_hex(stdout, key, info->key_size, " ");
                printf("\n");
                for (i = 0; i < n; i++) {
                        printf("value (CPU %02d):%c",
                               i, info->value_size > 16 ? '\n' : ' ');
-                       print_hex(value + i * info->value_size,
-                                 info->value_size, " ");
+                       fprint_hex(stdout, value + i * info->value_size,
+                                  info->value_size, " ");
                        printf("\n");
                }
        }
                        print_entry(&info, key, value);
                } else {
                        info("can't lookup element with key: ");
-                       print_hex(key, info.key_size, " ");
-                       printf("\n");
+                       fprint_hex(stderr, key, info.key_size, " ");
+                       fprintf(stderr, "\n");
                }
 
                prev_key = key;
                print_entry(&info, key, value);
        } else if (errno == ENOENT) {
                printf("key:\n");
-               print_hex(key, info.key_size, " ");
+               fprint_hex(stdout, key, info.key_size, " ");
                printf("\n\nNot found\n");
        } else {
                err("lookup failed: %s\n", strerror(errno));
 
        if (key) {
                printf("key:\n");
-               print_hex(key, info.key_size, " ");
+               fprint_hex(stdout, key, info.key_size, " ");
                printf("\n");
        } else {
                printf("key: None\n");
        }
 
        printf("next key:\n");
-       print_hex(nextkey, info.key_size, " ");
+       fprint_hex(stdout, nextkey, info.key_size, " ");
        printf("\n");
 
 exit_free: