What is it mkfifo linux

mkfifo() makes a FIFO special file with name pathname. mode specifies the FIFO's permissions. It is modified by the process's umask in the usual way: the permissions of the created file are (mode & ~umask).
A FIFO special file is similar to a pipe, except that it is created in a different way. Instead of being an anonymous communications channel, a FIFO special file is entered into the file system by calling mkfifo().

Once you have created a FIFO special file in this way, any process can open it for reading or writing, in the same way as an ordinary file. However, it has to be open at both ends simultaneously before you can proceed to do any input or output operations on it. Opening a FIFO for reading normally blocks until some other process opens the same FIFO for writing, and vice versa. See fifo(7) for nonblocking handling of FIFO special files.

The mkfifo() function shall create a new FIFO special file named by the pathname pointed to by path. The file permission bits of the new FIFO shall be initialized from mode. The file permission bits of the mode argument shall be modified by the process' file creation mask.

When bits in mode other than the file permission bits are set, the effect is implementation-defined.

If path names a symbolic link, mkfifo() shall fail and set errno to [EEXIST].



The FIFO's user ID shall be set to the process' effective user ID. The FIFO's group ID shall be set to the group ID of the parent directory or to the effective group ID of the process. Implementations shall provide a way to initialize the FIFO's group ID to the group ID of the parent directory. Implementations may, but need not, provide an implementation-defined way to initialize the FIFO's group ID to the effective group ID of the calling process.

Upon successful completion, mkfifo() shall mark for update the st_atime, st_ctime, and st_mtime fields of the file. Also, the st_ctime and st_mtime fields of the directory that contains the new entry shall be marked for update.


Once you have created a FIFO special file in this way, any process can open it for reading or writing, in the same way as an ordinary file. However, it has to be open at both ends simultaneously before you can proceed to do any input or output operations on it. Opening a FIFO for reading normally blocks until some other process opens the same FIFO for writing, and vice versa. See fifo(7) for nonblocking handling of FIFO special files.