Mycat

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define BUF_LIMIT 512

#define ec_meno1(s,m) \
if ( (s) == -1 ) {perror(m);}

int main( int argc, char *argv[] ){

    char *optstring = "o:";
    char buf[BUF_LIMIT];
    int opttype, i, l, j, fdin, fdout = STDOUT_FILENO, oflag=0;

    opterr = 0;

    if(argc < 2){
        printf("Syntax : mycat file1 ... file N [OPTIONS]\n");
        printf("Prints the content of file1 on stdout\n");
        printf("Option: -o fileout\n");
        printf("Prints the content of the input files on the specified output file\n");
        exit(-1);
    }

    while((opttype=getopt(argc,argv,optstring)) != -1)
        switch(opttype){
            case 'o' :
                ec_meno1((fdout = open(optarg,O_WRONLY|O_CREAT|O_APPEND)),"Couldn't open/create the output file");
                oflag=1;
                break;
            case '?' :
                if(optopt == 'o') printf("Option -o requires an argument\n");
                else printf("Illegal option\n");
                exit(-1);
            default :
                printf("Unknown error\n");
                exit(-1);
        };

    if(!oflag) j=1;
    else j=optind;
    for(i=j;i<argc;i++){
        printf("**********************\n");
        printf("Reading %s \n",argv[i]);
        printf("**********************\n");
        ec_meno1((fdin = open(argv[i],O_RDONLY)),"Couldn't open the file");
        while((l = read(fdin,buf,BUF_LIMIT))>0) ec_meno1((write(fdout,buf,l)),"Problem with the output file descriptor");
        ec_meno1(l,"Couldn't read the file");
            ec_meno1((close(fdin)),"Couldn't close the file");
        printf("\n");
    }
    if(oflag) ec_meno1((close(fdout)),"Couldn't close the file");;

    return 0;
}