NAME

creat − create a new file

SYNOPSIS

creat(name, mode)
char ∗name;

DESCRIPTION

This interface is obsoleted 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. 

NOTES

The mode given is arbitrary; it need not allow writing.  This feature has been used in the past by programs to construct a simple exclusive locking mechanism.  It is replaced by the O_EXCL open mode, or flock(2) facility.

The file thus created will inherit the parent directory’s group id.  The setgid option will only be set if the group of the file lies in the creating process’s group set, otherwise the option will be automatically turned off. 

RETURN VALUE

The value −1 is returned if an error occurs.  Otherwise, the call returns a non-negative descriptor which only permits writing. 

ERRORS

Creat will fail and the file will not be created or truncated if one of the following occur:

[EPERM] The argument contains a byte with the high-order bit set. 

[ENOTDIR] A component of the path prefix is not a directory. 

[EACCES] A needed directory does not have search permission. 

[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. 

[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. 

[EFAULT] Name points outside the process’s allocated address space. 

[ELOOP] Too many symbolic links were encountered in translating the pathname. 

[EOPNOTSUPP]
The file was a socket (not currently implemented).

[ENOENT] A component of the path name which must exist does not exist. 

[ENOENT] The path name was too long. 

[ENFILE] The file system 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 in which the file is being created. 

[EIO] An I/O error occurred while reading from or writing to the file system. 

SEE ALSO

open(2), write(2), close(2), chmod(2), umask(2)

4BSD