mkdir(3p) — Linux manual page

PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

MKDIR(3P)               POSIX Programmer's Manual              MKDIR(3P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior),
       or the interface may not be implemented on Linux.

NAME         top

       mkdir, mkdirat — make a directory

SYNOPSIS         top

       #include <sys/stat.h>

       int mkdir(const char *path, mode_t mode);

       #include <fcntl.h>

       int mkdirat(int fd, const char *path, mode_t mode);

DESCRIPTION         top

       The mkdir() function shall create a new directory with name path.
       The file permission bits of the new directory shall be
       initialized from mode.  These 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 meaning of these additional bits is implementation-defined.

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

       The newly created directory shall be an empty directory.

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

       Upon successful completion, mkdir() shall mark for update the
       last data access, last data modification, and last file status
       change timestamps of the directory. Also, the last data
       modification and last file status change timestamps of the
       directory that contains the new entry shall be marked for update.

       The mkdirat() function shall be equivalent to the mkdir()
       function except in the case where path specifies a relative path.
       In this case the newly created directory is created relative to
       the directory associated with the file descriptor fd instead of
       the current working directory. If the access mode of the open
       file description associated with the file descriptor is not
       O_SEARCH, the function shall check whether directory searches are
       permitted using the current permissions of the directory
       underlying the file descriptor. If the access mode is O_SEARCH,
       the function shall not perform the check.

       If mkdirat() is passed the special value AT_FDCWD in the fd
       parameter, the current working directory shall be used and the
       behavior shall be identical to a call to mkdir().

RETURN VALUE         top

       Upon successful completion, these functions shall return 0.
       Otherwise, these functions shall return -1 and set errno to
       indicate the error. If -1 is returned, no directory shall be
       created.

ERRORS         top

       These functions shall fail if:

       EACCES Search permission is denied on a component of the path
              prefix, or write permission is denied on the parent
              directory of the directory to be created.

       EEXIST The named file exists.

       ELOOP  A loop exists in symbolic links encountered during
              resolution of the path argument.

       EMLINK The link count of the parent directory would exceed
              {LINK_MAX}.

       ENAMETOOLONG
              The length of a component of a pathname is longer than
              {NAME_MAX}.

       ENOENT A component of the path prefix specified by path does not
              name an existing directory or path is an empty string.

       ENOSPC The file system does not contain enough space to hold the
              contents of the new directory or to extend the parent
              directory of the new directory.

       ENOTDIR
              A component of the path prefix names an existing file that
              is neither a directory nor a symbolic link to a directory.

       EROFS  The parent directory resides on a read-only file system.

       In addition, the mkdirat() function shall fail if:

       EACCES The access mode of the open file description associated
              with fd is not O_SEARCH and the permissions of the
              directory underlying fd do not permit directory searches.

       EBADF  The path argument does not specify an absolute path and
              the fd argument is neither AT_FDCWD nor a valid file
              descriptor open for reading or searching.

       ENOTDIR
              The path argument is not an absolute path and fd is a file
              descriptor associated with a non-directory file.

       These functions may fail if:

       ELOOP  More than {SYMLOOP_MAX} symbolic links were encountered
              during resolution of the path argument.

       ENAMETOOLONG
              The length of a pathname exceeds {PATH_MAX}, or pathname
              resolution of a symbolic link produced an intermediate
              result with a length that exceeds {PATH_MAX}.

       The following sections are informative.

EXAMPLES         top

   Creating a Directory
       The following example shows how to create a directory named
       /home/cnd/mod1, with read/write/search permissions for owner and
       group, and with read/search permissions for others.

           #include <sys/types.h>
           #include <sys/stat.h>

           int status;
           ...
           status = mkdir("/home/cnd/mod1", S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);

APPLICATION USAGE         top

       None.

RATIONALE         top

       The mkdir() function originated in 4.2 BSD and was added to
       System V in Release 3.0.

       4.3 BSD detects [ENAMETOOLONG].

       The POSIX.1‐1990 standard required that the group ID of a newly
       created directory be set to the group ID of its parent directory
       or to the effective group ID of the creating process. FIPS 151‐2
       required that implementations provide a way to have the group ID
       be set to the group ID of the containing directory, but did not
       prohibit implementations also supporting a way to set the group
       ID to the effective group ID of the creating process.  Conforming
       applications should not assume which group ID will be used. If it
       matters, an application can use chown() to set the group ID after
       the directory is created, or determine under what conditions the
       implementation will set the desired group ID.

       The purpose of the mkdirat() function is to create a directory in
       directories other than the current working directory without
       exposure to race conditions. Any part of the path of a file could
       be changed in parallel to the call to mkdir(), resulting in
       unspecified behavior. By opening a file descriptor for the target
       directory and using the mkdirat() function it can be guaranteed
       that the newly created directory is located relative to the
       desired directory.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       chmod(3p), mkdtemp(3p), mknod(3p), umask(3p)

       The Base Definitions volume of POSIX.1‐2017, fcntl.h(0p),
       sys_stat.h(0p), sys_types.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any
       discrepancy between this version and the original IEEE and The
       Open Group Standard, the original IEEE and The Open Group
       Standard is the referee document. The original Standard can be
       obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                         MKDIR(3P)

Pages that refer to this page: sys_stat.h(0p)mkdir(1p)pax(1p)chmod(3p)mkdtemp(3p)mknod(3p)rmdir(3p)umask(3p)