how to read from an existing proc file ( specifically /proc/<pid>/status )

proc-read.c

// compile: gcc -Wall -o proc proc-read.c
// citation: https://bbs.archlinux.org/viewtopic.php?id=96068

#include <stdio.h>
#include <stdlib.h>
#define BUFFER_SIZE 1024

void die(char *x){ perror(x); exit(1); };

int main(int argc, char **argv)
{
	int n = 0;
	char    filepath[BUFFER_SIZE], buf[BUFFER_SIZE];
	FILE    *f = NULL;
    
	//get the filename to open
        //eg usage: proc-read "2837/status" 
	if(argc < 2){
		fprintf(stderr, "Usage: %s <proc file>\n", argv[0]);
	return 1;
}
    
	//get the path of the file
	n = snprintf(filepath, BUFFER_SIZE-1, "/proc/%s", argv[1]);
	filepath[n] = 0;
    
	//open the file
	f = fopen(filepath, "r");
	if(!f)
		die("fopen");

	//print its contents
	while(fgets(buf, BUFFER_SIZE-1, f))
		printf("%s", buf);

	if(ferror(f))
		die("fgets");

	fclose(f);

	return 0;
}