man-pages/man3/mkfifo.3

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.TH MKFIFO 3 1995-09-03 "GNU" "Linux Programmer's Manual"
.SH NAME
mkfifo \- make a FIFO special file (a named pipe)
.SH SYNOPSIS
.nf
.B #include <sys/types.h>
.B #include <sys/stat.h>
.sp
.BI "int mkfifo(const char *" pathname ", mode_t " mode );
.fi
.SH DESCRIPTION
.BR mkfifo ()
makes a FIFO special file with name \fIpathname\fP.
\fImode\fP specifies the FIFO's permissions.
It is modified by the
process's \fBumask\fP in the usual way: the permissions of the created
file are \fB(\fP\fImode\fP\fB & ~umask)\fP.
.PP
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
.BR mkfifo ().
.PP
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
.BR fifo (7)
for non-blocking handling of FIFO special files.
.SH "RETURN VALUE"
On success
.BR mkfifo ()
returns 0.
In the case of an error, \-1 is returned (in which case, \fIerrno\fP
is set appropriately).
.SH ERRORS
.TP
.B EACCES
One of the directories in \fIpathname\fP did not allow search
(execute) permission.
.TP
.B EEXIST
\fIpathname\fP already exists.
.TP
.B ENAMETOOLONG
Either the total length of \fIpathname\fP is greater than
\fBPATH_MAX\fP, or an individual filename component has a length
greater than \fBNAME_MAX\fP.
In the GNU system, there is no imposed
limit on overall filename length, but some file systems may place
limits on the length of a component.
.TP
.B ENOENT
A directory component in \fIpathname\fP does not exist or is a
dangling symbolic link.
.TP
.B ENOSPC
The directory or file system has no room for the new file.
.TP
.B ENOTDIR
A component used as a directory in \fIpathname\fP is not, in fact, a
directory.
.TP
.B EROFS
\fIpathname\fP refers to a read-only file system.
.SH "CONFORMING TO"
POSIX.1-2001.
.SH "SEE ALSO"
.BR mkfifo (1),
.BR close (2),
.BR open (2),
.BR read (2),
.BR stat (2),
.BR umask (2),
.BR write (2),
.BR mkfifoat (3),
.BR fifo (7)