MKDIR(2)

💖 MKDIR(2) — bestie, we're making a directory 💖

okay so this is the System Calls Manual page for mkdir and mkdirat, and honestly? it's giving "let me just make a folder real quick" and I'm obsessed. 🎀

---

✨ NAME ✨

mkdir, mkdirat — make a directory file 🌸

📚 LIBRARY 📚

Standard C Library (libc, -lc) 🫶

🦋 SYNOPSIS 🦋

#include <sys/stat.h>

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

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

👑 DESCRIPTION 👑

so the directory at path gets created with the access permissions you specified in mode, restricted by the umask(2) of the calling process. yes bestie the umask gets a vote too, it's a whole committee situation.

The directory's owner ID is set to the process's effective user ID. The directory's group ID is set to that of the parent directory in which it is created. so like, it inherits the group from its mom directory. iconic behavior honestly. 💅

Now mkdirat() — she's the same as mkdir() except when path is a relative path. In that case, the newly created directory is created relative to the directory associated with the file descriptor fd instead of the current working directory. The way that works is just chef's kiss. ✨

And if you pass mkdirat() the special value AT_FDCWD in the fd parameter, the current working directory is used and the behavior is identical to a call to mkdir(). lowkey convenient ngl.

🎀 RETURN VALUES 🎀

The mkdir() function returns the value 0 if successful. otherwise you get -1 returned and the global variable errno is set to indicate the error. no cap. 😭

🔥 ERRORS 🔥

The mkdir() system call will fail and no directory will be created if:

• [ENOTDIR] — A component of the path prefix is not a directory.
• [ENAMETOOLONG] — A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters. 💀
• [ENOENT] — A component of the path prefix does not exist.
• [EACCES] — Search permission is denied for a component of the path prefix, or write permission is denied on the parent directory of the directory to be created.
• [ELOOP] — Too many symbolic links were encountered in translating the pathname.
• [EPERM] — The parent directory of the directory to be created has its immutable flag set, see the chflags(2) manual page for more information. 🔒
• [EROFS] — The named directory would reside on a read-only file system.
• [EMLINK] — The new directory cannot be created because the parent directory contains too many subdirectories. it's full bestie, no room for you 😭
• [EEXIST] — The named file exists.
• [ENOSPC] — The new directory cannot be created because there is no space left on the file system that will contain the directory.
• [ENOSPC] — There are no free inodes on the file system on which the directory is being created.
• [EDQUOT] — The new directory cannot be created because the user's quota of disk blocks on the file system that will contain the directory has been exhausted.
• [EDQUOT] — The user's quota of inodes on the file system on which the directory is being created has been exhausted.
• [EIO] — An I/O error occurred while making the directory entry or allocating the inode.
• [EIO] — An I/O error occurred while reading from or writing to the file system.
• [EINTEGRITY] — Corrupted data was detected while reading from the file system.
• [EFAULT] — The path argument points outside the process's allocated address space.

In addition to the errors returned by the mkdir(), the mkdirat() may fail if:

• [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 searching.
• [ENOTDIR] — The path argument is not an absolute path and fd is neither AT_FDCWD nor a file descriptor associated with a directory.

🌈 SEE ALSO 🌈

chflags(2), chmod(2), stat(2), umask(2) — go read these next bestie, they're all in the group chat 🫶

⭐ STANDARDS ⭐

The mkdir() system call is expected to conform to ISO/IEC 9945-1:1990 ("POSIX.1"). The mkdirat() system call follows The Open Group Extended API Set 2 specification. she's certified ✨

💜 HISTORY 💜

The mkdirat() system call appeared in FreeBSD 8.0. The mkdir() system call appeared in Version 1 AT&T UNIX. ancient icon behavior, we love a legend. 👑

---

fr fr that's the whole page, nothing skipped, every flag accounted for. periodt. 💅

🌸 that's a wrap, bestie 🌸 — this came from the Debian edition of the page, dated March 30, 2020, and the header/footer tag on it is MKDIR(2) for both the System Calls Manual and the page title. go make some directories, you got this 🎀🦋✨