Notes

int main(int argc, char **argv)
{
if (argc<3) {
fprintf(stderr,"malo parametrovn");exit(21);
}

DIR *adresar;
struct dirent *subor;

int in,out,received=1; //deskriptor otvoreneho suboru
char buf[256]; //buffer, do ktoreho nacitavame

if (strcmp(argv[1],"-D")==0){
adresar=opendir(argv[argc-2]);
if (adresar==NULL) {
fprintf(stderr,"opendirCHYBAn");
return(28);
}
}

else{

in=open(argv[argc-2],O_RDONLY); //otvorime subor

if (in==-1) {
if (errno==2) {
fprintf(stderr,"SUBOR NEEXISTUJEn");
}
else {
fprintf(stderr,"INA CHYBAn");
}
return(21);
}
}

if (strcmp(argv[1], "-a")==0){ //test ci je prepinac -a zapnuty
out=open(argv[argc-1],O_WRONLY |O_APPEND); //otvorenie na append
if (in==-1) {
if (errno==2) {
fprintf(stderr,"SUBOR NEEXISTUJEn");
}
else {
fprintf(stderr,"INA CHYBAn");
}
return(22);
}
}

else{
out=open(argv[argc-1],O_WRONLY | O_TRUNC | O_CREAT, S_IWUSR | S_IRUSR);
}

if (out==-1) {
fprintf(stderr,"INA CHYBAn");
return(21);
}
if (strcmp(argv[1],"-D")==0) {
while ((subor=readdir(adresar))!=NULL){ //Citame kym je co citat
write(out,subor->d_name, strlen(subor->d_name)); //A vypiseme nazov suboru
write(out,"n",1);
}
closedir(adresar); //A nakoniec adresar zatvorime
}

else {

while(received>0) {
received = read(in,&buf,255); //nacitame z neho 255 znakov
write(out,&buf,received); //a vypiseme na standardny vystup
}
close(in);

close(out); //subor znova zatvorime
}

if (strcmp(argv[1], "-d")==0){
if (remove(argv[argc-2])==-1){
fprintf(stderr,"SUBOR NEZMAZANYn");
return(26) ;
}
}

return 0;
}