fixed --help

src/userland/cli/tail.c

@@ -6,13 +6,13 @@
 #include <stdlib.h>
 
 int main(int argc, char *argv[]) {
+    // print all lines
     if (argc == 2) {
         if (strcmp(argv[1], "--help") == 0) {
-            printf("-This command reads from the front of the file\n");
+            printf("-This command reads from the back of the file\n");
             printf("-Use: tail [-n] [-number of lines] [file]\n");
             return 0;
         }
-        //print everything
         FILE *fp = fopen(argv[1], "r");
         if (fp == NULL) {
             printf("File not found\n");
@@ -25,7 +25,7 @@ int main(int argc, char *argv[]) {
         fclose(fp);
         return 0;
     }
-    // only print first lines
+    // only print last lines 
     if (argc == 4 && strcmp(argv[1], "-n") == 0) {
         int lines = atoi(argv[2]);
         if (lines <= 0) {
@@ -39,10 +39,24 @@ int main(int argc, char *argv[]) {
             return 1;
         }
 
+        // count total lines
+        int count = 0;
         char buf[1024];
-        while (lines > 0 && fgets(buf, sizeof(buf), fp)) {
-            printf("%s", buf);
-            lines--;
+        while (fgets(buf, sizeof(buf), fp)) {
+            count++;
+        }
+
+        // back to start of file
+        fseek(fp, 0, SEEK_SET);
+
+        // check if lines are the end lines
+        int skip = count - lines;
+        int i = 0;
+        while (fgets(buf, sizeof(buf), fp)) {
+            if (i >= skip) {
+                printf("%s", buf);
+            }
+            i++;
         }
 
         fclose(fp);