这根管怎么了？

Question

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

int main (int argc, char * argv[])
{
    int enteroParaElPipe;  
    int IDPROGRAMACLIENTE=getpid(); 
    printf("%d",IDPROGRAMACLIENTE);

    if((mkfifo("pipe",0666))==-1) 
    {
        perror("error creating pipe, type 1");
        exit(1);
    }

    if((enteroParaElPipe=open("pipe",O_WRONLY))==-1)
    {
       perror("error creating pipe, type 2");
       exit(1);
    }

    char comando[200];

    if(scanf("%199s", comando) == 1)
         puts(comando);

    int written;
    escritos=write(enteroParaElPipe,"HOLA\n",5);
    printf("Written: %d\n",written);
    close(enteroParaElPipe);

    return 0;
}

When trying to run this code I get:

error creating pipe: Invalid argument

Why?

(Modifications based on the first answers added)

Answer 1

Why are you passing getpid() as the 2nd argument for mkfifo?

The 2nd argument is the mode, as in, the FIFO file's permissions. Type man 3 mkfifo for more information!

Cheers.

Answer 2

The second argument to mkfifo is a mode_t representing the permissions on the fifo.

Try: mkfifo("pipe", 0666);