getting segmentation fault when attempting to read text file contraining 1 byte of hex value per line in c

was trying to write some c code to read a text file which contains some hex value in the follow format

AA
BB
CC
DD

Containing 1 Byte of hex values per line in the file.

the following is the code I used to attempt to read 1 byte of Hex values per read

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

char* file_path;
FILE *fp;
uint8_t tmp_hex;
char buf[1L<<15];

int main (){
  file_path = "./hex.txt";
  printf("0\n");
  fp = fopen(file_path, "rb");
  printf("1\n");
  fscanf(fp, "%02X\n", tmp_hex);
  printf("2\n");
  *buf = tmp_hex;
}

the code seems to work up to print("1\n"); since 1 is the last thing I see printed in terminal before I receive an error message segmentation fault (core dumped) what am I doing wrong when reading the text file?

The end goal is to read every byte in the text file and store into buf for binary manipulation

fscanf(fp, "%02X\n", tmp_hex);

You need to pass a reference to an unsigned int variable. So you have 2 UBs in this line of code:

1. You do not pass the reference (pointer)
2. tmp_hex has the wrong type.

If fp is NULL it will invoke another UB.

You want: fscanf(fp, "%2hhX", &tmp_hex);

You should also check the result of I/O operations as they may fail.