wc/wc.c

#include <stdio.h>
#include <unistd.h> // read, isatty

// STDIN_FILENO
int process_fp(FILE* fp)
{
    char buffer[1];
    while (read(0, buffer, sizeof(buffer)) > 0) {
        printf("%c", buffer[0]);
    }
		return 0;
}

int main(int argc, char** argv)
{
    //
    if (!isatty(STDIN_FILENO)) { // check if stdin is coming from terminal or pipeline
        return process_fp(STDIN_FILENO);
    } else if(argc > 1){
			printf("To do");
		}
    return 0;
}