man3/mkfifo.3

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  27 .TH MKFIFO 3 1995-09-03 "Linux 1.2.13" "Linux Programmer's Manual"
  28 .SH NAME
  29 mkfifo \- make a FIFO special file (a named pipe)
  30 .SH SYNOPSIS
  31 .nf
  32 .B #include <sys/types.h>
  33 .B #include <sys/stat.h>
  34 .sp
  35 .BI "int mkfifo(const char *" pathname ", mode_t " mode );
  36 .fi
  37 .SH DESCRIPTION
  38 \fBmkfifo\fP() makes a FIFO special file with name \fIpathname\fP.
  39 \fImode\fP specifies the FIFO's permissions. It is modified by the
  40 process's \fBumask\fP in the usual way: the permissions of the created
  41 file are \fB(\fP\fImode\fP\fB & ~umask)\fP.
  42 .PP
  43 A FIFO special file is similar to a pipe, except that it is created
  44 in a different way.  Instead of being an anonymous communications
  45 channel, a FIFO special file is entered into the file system by
  46 calling \fBmkfifo\fP().
  47 .PP
  48 Once you have created a FIFO special file in this way, any process can
  49 open it for reading or writing, in the same way as an ordinary file.
  50 However, it has to be open at both ends simultaneously before you can
  51 proceed to do any input or output operations on it.  Opening a FIFO
  52 for reading normally blocks until some other process opens the same
  53 FIFO for writing, and vice versa. See
  54 .BR fifo (7)
  55 for non-blocking handling of FIFO special files.
  56 .SH "RETURN VALUE"
  57 On success \fImkfifo\fP() returns 0.  In
  58 the case of an error, -1 is returned (in which case, \fIerrno\fP
  59 is set appropriately).
  60 .SH ERRORS
  61 .TP
  62 .B EACCES
  63 One of the directories in \fIpathname\fP did not allow search
  64 (execute) permission.
  65 .TP
  66 .B EEXIST
  67 \fIpathname\fP already exists.
  68 .TP
  69 .B ENAMETOOLONG
  70 Either the total length of \fIpathname\fP is greater than
  71 \fBPATH_MAX\fP, or an individual filename component has a length
  72 greater than \fBNAME_MAX\fP.  In the GNU system, there is no imposed
  73 limit on overall filename length, but some file systems may place
  74 limits on the length of a component.
  75 .TP
  76 .B ENOENT
  77 A directory component in \fIpathname\fP does not exist or is a
  78 dangling symbolic link.
  79 .TP
  80 .B ENOSPC
  81 The directory or filesystem has no room for the new file.
  82 .TP
  83 .B ENOTDIR
  84 A component used as a directory in \fIpathname\fP is not, in fact, a
  85 directory.
  86 .TP
  87 .B EROFS
  88 \fIpathname\fP refers to a read-only filesystem.
  89 .SH "CONFORMING TO"
  90 POSIX.1-2001.
  91 .SH "SEE ALSO"
  92 .BR mkfifo (1),
  93 .BR close (2),
  94 .BR open (2),
  95 .BR read (2),
  96 .BR stat (2),
  97 .BR umask (2),
  98 .BR write (2),
  99 .BR mkfifoat (3),
 100 .BR fifo (7)