The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.

#### NAME

> mkdir - make a directory

#### SYNOPSIS

> ``#include <sys/stat.h>
> int mkdir(const char *`path`, mode_t` mode`);
> ``

#### DESCRIPTION

> 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 st_atime, st_ctime, and st_mtime fields of the directory. Also, the st_ctime and st_mtime fields of the directory that contains the new entry shall be marked for update.

#### RETURN VALUE

> Upon successful completion, mkdir() shall return 0. Otherwise, -1 shall be returned, no directory shall be created, and errno shall be set to indicate the error.

#### ERRORS

> The mkdir() function 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 the path argument exceeds {PATH_MAX} or a pathname component 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 is not a directory.
> [EROFS]
>   The parent directory resides on a read-only file system.

> The mkdir() function may fail if:

> [ELOOP]
>   More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the path argument.
> [ENAMETOOLONG]
>   As a result of encountering a symbolic link in resolution of the path argument, the length of the substituted pathname string exceeded {PATH_MAX}.

The following sections are informative.

#### EXAMPLES

> ##### 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

> None.

#### RATIONALE

> 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.

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> umask(), the Base Definitions volume of IEEE Std 1003.1-2001, <sys/stat.h>, <sys/types.h>

#### CHANGE HISTORY

> First released in Issue 3. Included for alignment with the POSIX.1-1988 standard.

#### Issue 6

> In the SYNOPSIS, the optional include of the <sys/types.h> header is removed.

> The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:

> - The requirement to include <sys/types.h> has been removed. Although <sys/types.h> was required for conforming implementations of previous POSIX specifications, it was not required for UNIX applications.

> - The [ELOOP] mandatory error condition is added.

> - A second [ENAMETOOLONG] is added as an optional error condition.

> The following changes were made to align with the IEEE P1003.1a draft standard:

> - The [ELOOP] optional error condition is added.

End of informative text.

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