cat

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>

#define BUFFERSIZE 4096
#define COPYMODE 0644
#define STDOUT 2
void FilePrinter(int,int, FILE *);

int main(int ac, char *av[])
{
    int  in_fd, out_fd, n_chars, flag;
    int i;
    char buf[BUFFERSIZE];
    FILE *fp;

    /* check arguments */
    //if (ac != 3){
        //fprintf(stderr, "usage: %s source destination\n", *av);
        //return 1;
    //}

    if (strcmp(av[1], "-e") == 0 )
    {
        flag = 1;
    }
    else if (strcmp(av[1], "-n") == 0 )
    {
        flag = 2;
    }
    else if (strcmp(av[1], "-s") == 0 )
    {
        flag = 3;
    }
    else
    {
        flag = 0;
    }

    if(flag == 0)
    {
        i = 1;
    }
    else
    {
        i = 2;
    }
    for( ; i <= ac; i++)
    {
        fp = fopen(av[i], "r");
        //if ((in_fd=open(av[i], O_RDONLY)) == -1)
        //{
            //perror("Cannot open source file");
            //return 1;
        //}
        FilePrinter(in_fd, flag, fp);
    }


}

void FilePrinter(int iFileHandler, int treatment, FILE * ffp)
{
    char buf[BUFFERSIZE];
    //while ((n_chars = read(iFileHandler, buf, BUFFERSIZE)) > 0)
    while(fgets(buf, BUFFERSIZE, ffp) != NULL)
    {
        if(treatment == 0)
        {
            //if (write(STDOUT, buf, n_chars) != n_chars)
            //{
                //perror("Write error");
                //return 1;
            //}
            printf("%s", buf);
        }
        if( treatment == 1)
        {
            char tempBuf[strlen(buf) + 2];
            strncpy(tempBuf, buf, strlen(buf)+2);
            tempBuf[strlen(buf) - 1] = '$';
            tempBuf[strlen(buf)] = '\n';
            tempBuf[strlen(buf) + 1] = '\0';
            printf("%s", tempBuf);
        }
    }
}