From f436eb959f08b8b342b0360ae439f922191638e8 Mon Sep 17 00:00:00 2001
From: Minecon724 <git@m724.eu>
Date: Mon, 15 Jul 2024 12:03:20 +0200
Subject: [PATCH] fix

---
 README.md |  5 +++--
 main.c    | 10 +++++-----
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index 06666df..42dca31 100644
--- a/README.md
+++ b/README.md
@@ -7,9 +7,10 @@ a lightweight script that logs the most important stuff about the raspberry pi
 CPU temperature is read from `/sys/class/thermal/thermal_zone0/temp` but that should work on every Linux computer \
 Ambient temperature is read from `/sys/bus/w1/devices` so you must have 1wire enabled, if you don't have that set `SENSOR` to `0`
 
-# compilation
+# compilation and usage
 `make` or `gcc main.c -o measurer` \
-Should throw no warnings
+Should throw no warnings \
+`./measurer <output>`
 
 # why
 like heavy ahh like databases grafana etc go away you're a performance monitor why'd you reduce performance
\ No newline at end of file
diff --git a/main.c b/main.c
index f06573d..89ab093 100644
--- a/main.c
+++ b/main.c
@@ -7,7 +7,7 @@
 #include <errno.h>
 #include <time.h>
 
-#define SENSOR 1
+#define SENSOR 0
 
 int read_temperature(char *filename) {
     FILE *fp;
@@ -70,7 +70,7 @@ int read_w1_temperature(char *w1_id) {
 }
 
 int main(int argc, char *argv[]) {
-    if (argc == 0) {
+    if (argc < 2) {
         printf("Filename required\n");
         return 1;
     }
@@ -105,14 +105,14 @@ int main(int argc, char *argv[]) {
 
 
     FILE *fp;
-    fp = fopen(argv[0], "a");
+    fp = fopen(argv[1], "a");
 
     if (fp == NULL) {
-        printf("Error opening output file");
+        perror("Error opening output file");
         return 1;
     }
 
-    if (fprintf(fp, line) != 0) {
+    if (fprintf(fp, line) < 0) {
         perror("Error writing to output file");
         fclose(fp);
         return 1;