CREAT(2) System Calls Manual CREAT(2)
creat - create a new file
This interface is made obsolete by open(2).
Creat creates a new file or prepares to rewrite an existing file called name, given as the address of a null-terminated string. If the
file did not exist, it is given mode mode, as modified by the process's mode mask (see umask(2)). Also see chmod(2) for the construction
of the mode argument.
If the file did exist, its mode and owner remain unchanged but it is truncated to 0 length.
The file is also opened for writing, and its file descriptor is returned.
The mode given is arbitrary; it need not allow writing. This feature has been used in the past by programs to construct a simple, exclu-
sive locking mechanism. It is replaced by the O_EXCL open mode, or flock(2) facility.
The value -1 is returned if an error occurs. Otherwise, the call returns a non-negative descriptor that only permits writing.
Creat will fail and the file will not be created or truncated if one of the following occur:
[ENOTDIR] A component of the path prefix is not a directory.
[EINVAL] The pathname contains a character with the high-order bit set.
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.
[ENOENT] The named file does not exist.
[ELOOP] Too many symbolic links were encountered in translating the pathname.
[EACCES] Search permission is denied for a component of the path prefix.
[EACCES] The file does not exist and the directory in which it is to be created is not writable.
[EACCES] The file exists, but it is unwritable.
[EISDIR] The file is a directory.
[EMFILE] There are already too many files open.
[ENFILE] The system file table is full.
[ENOSPC] The directory in which the entry for the new file is being placed cannot be extended because there is no space left on the
file system containing the directory.
[ENOSPC] There are no free inodes on the file system on which the file is being created.
[EDQUOT] The directory in which the entry for the new file is being placed cannot be extended because the user's quota of disk blocks
on the file system containing the directory has been exhausted.
[EDQUOT] The user's quota of inodes on the file system on which the file is being created has been exhausted.
[EROFS] The named file resides on a read-only file system.
[ENXIO] The file is a character special or block special file, and the associated device does not exist.
[ETXTBSY] The file is a pure procedure (shared text) file that is being executed.
[EIO] An I/O error occurred while making the directory entry or allocating the inode.
[EFAULT] Name points outside the process's allocated address space.
[EOPNOTSUPP] The file was a socket (not currently implemented).
open(2), write(2), close(2), chmod(2), umask(2)
4th Berkeley Distribution May 22, 1986 CREAT(2)