CODEWITHSUNDEEP
clinuxubuntufifo
ghadeer darwesh
ghadeer darwesh

Reputation: 185

How to make a fifo special file in C?

I have to use mkfifo in my C program in Ubuntu. But I have an error when I run the code: no such file or directory .

I think the problem because I have not set the panel_fifo environment variables. But I don't know how could I do this.

Here is my code I use to test this method:

char *myfifo="./sock/myfifo";

if (mkfifo(myfifo,0777)<0)
    perror("can't make it");

if (fd=open(myfifo,O_WRONLY)<0)
    perror("can't open it");

I compile this with:

gcc gh.c -o gh

When I run, I get this error message:

can't make it:no such file or directory
can't open it:no such file or directory

Upvotes: 1

Views: 722

Answers (1)

Jonathan Leffler
Jonathan Leffler

Reputation: 754920

See How can I create a directory tree in C++/Linux for a general C (and C++) solution to creating a directory path. For the immediate problem, that is overkill and a direct call to mkdir() suffices.

const char dir[] = "./sock";
const char fifo[] = "./sock/myfifo";
int fd;

if (mkdir(dir, 0755) == -1 && errno != EEXIST)
    perror("Failed to create directory: ");
else if (mkfifo(fifo, 0600) == -1 && errno != EEXIST)
    perror("Failed to create fifo: ");
else if ((fd = open(fifo, O_WRONLY)) < 0)
    perror("Failed to open fifo for writing: ");
else
{
    …use opened fifo…
    close(fd);
}

I'm assuming you have the correct headers included, of course (<errno.h>, <fcntl.h>, <stdio.h>, <stdlib.h>, <sys/stat.h>, <unistd.h>, I believe).

Note the parentheses around the assignment in the if that opens the FIFO.

Upvotes: 3

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