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man:mkfifo

MKFIFO(3) Linux Programmer's Manual MKFIFO(3)

NAME

     mkfifo, mkfifoat - make a FIFO special file (a named pipe)

SYNOPSIS

     #include <sys/types.h>
     #include <sys/stat.h>
     int mkfifo(const char *pathname, mode_t mode);
     #include <fcntl.h>           /* Definition of AT_* constants */
     #include <sys/stat.h>
     int mkfifoat(int dirfd, const char *pathname, mode_t mode);
 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
     mkfifoat():
         Since glibc 2.10:
             _POSIX_C_SOURCE >= 200809L
         Before glibc 2.10:
             _ATFILE_SOURCE

DESCRIPTION

     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 filesystem 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.
 mkfifoat()
     The mkfifoat() function operates in exactly the same way  as  mkfifo(),
     except for the differences described here.
     If  the  pathname given in pathname is relative, then it is interpreted
     relative to the directory referred to  by  the  file  descriptor  dirfd
     (rather  than  relative to the current working directory of the calling
     process, as is done by mkfifo() for a relative pathname).
     If pathname is relative and dirfd is the special value  AT_FDCWD,  then
     pathname  is  interpreted  relative to the current working directory of
     the calling process (like mkfifo()).
     If pathname is absolute, then dirfd is ignored.

RETURN VALUE

     On success mkfifo() and mkfifoat() return 0.  In the case of an  error,
     -1 is returned (in which case, errno is set appropriately).

ERRORS

     EACCES One  of  the  directories in pathname did not allow search (exe-
            cute) permission.
     EDQUOT The user's quota of disk blocks or inodes on the filesystem  has
            been exhausted.
     EEXIST pathname  already exists.  This includes the case where pathname
            is a symbolic link, dangling or not.
     ENAMETOOLONG
            Either the total length of pathname is greater than PATH_MAX, or
            an  individual  filename  component  has  a  length greater than
            NAME_MAX.  In the GNU system, there is no imposed limit on over-
            all  filename  length,  but some filesystems may place limits on
            the length of a component.
     ENOENT A directory component in pathname does not exist or  is  a  dan-
            gling symbolic link.
     ENOSPC The directory or filesystem has no room for the new file.
     ENOTDIR
            A  component  used as a directory in pathname is not, in fact, a
            directory.
     EROFS  pathname refers to a read-only filesystem.
     The following additional errors can occur for mkfifoat():
     EBADF  dirfd is not a valid file descriptor.
     ENOTDIR
            pathname is a relative path  and  dirfd  is  a  file  descriptor
            referring to a file other than a directory.

VERSIONS

     mkfifoat()  was added to glibc in version 2.4.  It is implemented using
     mknodat(2), available on Linux since kernel 2.6.16.

ATTRIBUTES

     For  an  explanation  of  the  terms  used   in   this   section,   see
     attributes(7).
     +---------------------+---------------+---------+
     |Interface            | Attribute     | Value   |
     +---------------------+---------------+---------+
     |mkfifo(), mkfifoat() | Thread safety | MT-Safe |
     +---------------------+---------------+---------+

CONFORMING TO

     mkfifo(): POSIX.1-2001, POSIX.1-2008.
     mkfifoat(): POSIX.1-2008.

SEE ALSO

     mkfifo(1), close(2), open(2),  read(2),  stat(2),  umask(2),  write(2),
     fifo(7)

COLOPHON

     This  page  is  part of release 4.16 of the Linux man-pages project.  A
     description of the project, information about reporting bugs,  and  the
     latest     version     of     this    page,    can    be    found    at
     https://www.kernel.org/doc/man-pages/.

GNU 2017-09-15 MKFIFO(3)

/data/webs/external/dokuwiki/data/pages/man/mkfifo.txt · Last modified: 2019/05/17 09:47 by 127.0.0.1

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