CREAT(S) UNIX System V CREAT(S)
Name
creat - create a new file or rewrite an existing one
Syntax
#include <sys/types.h>
#include <sys/stat.h>
int creat (path, mode)
char *path;
int mode;
Description
The creat system call creates a new ordinary file or
prepares to rewrite an existing file named by the path name
pointed to by path.
If the file exists, the length is truncated to 0 and the
mode and owner are unchanged. Otherwise, the file's owner
ID is set to the effective user ID of the process; the group
ID of the process is set to the effective group ID of the
process; and the low-order 12 bits of the file mode are set
to the value of mode modified as follows:
All bits set in the process's file mode creation mask
are cleared (see umask(S)).
The ``save text image after execution bit'' of the mode
is cleared (see chmod(S)).
Upon successful completion, a write-only file descriptor is
returned and the file is open for writing, even if the mode
does not permit writing. The file pointer is set to the
beginning of the file. The file descriptor is set to remain
open across exec system calls (see fcntl(S)). No process
may have more than 20 files open simultaneously. A new file
may be created with a mode that forbids writing.
Symbolic constants defining the access permission bits are
specified in the <sys/stat.h> header file and should be used
to construct mode (see chmod(S)).
The call creat(path, mode) is equivalent to the following
(see open(S)):
open(path, O_WRONLY | O_CREAT | O_TRUNC, mode)
The creat system call fails if one or more of the following
is true:
[ENOTDIR] A component of the path prefix is not a
directory.
[ENOENT] A component of the path prefix does not
exist.
[EACCES] Search permission is denied on a component of
the path prefix.
[ENOENT] The path name is null.
[EACCES] The file does not exist and the directory in
which the file is to be created does not
permit writing.
[EROFS] The named file resides or would reside on a
read-only file system.
[ETXTBSY] The file is a pure procedure (shared text)
file that is being executed.
[EACCES] The file exists and write permission is
denied.
[EISDIR] The named file is an existing directory.
[EMFILE] NOFiles file descriptors are currently open.
[EFAULT] The path argument points outside the
allocated address space of the process.
[ENFILE] The system file table is full.
[EAGAIN] The file exists, mandatory file/record
locking is set, and there are outstanding
record locks on the file (see chmod(S)).
[EINTR] A signal was caught during the creat system
call.
[ENOLINK] path points to a remote machine and the link
to that machine is no longer active.
[EMULTIHOP] Components of path require hopping to
multiple remote machines.
[ENOSPC] The file system is out of inodes.
See Also
chmod(S), close(S), dup(S), fcntl(S), lseek(S), open(S),
read(S), umask(S), write(S).
Diagnostics
Upon successful completion, a non-negative integer, namely
the file descriptor, is returned. Otherwise, a value of -1
is returned, and errno is set to indicate the error.
Standards Conformance
creat is conformant with:
AT&T SVID Issue 2, Select Code 307-127;
The X/Open Portability Guide II of January 1987;
IEEE POSIX Std 1003.1-1988 with C Standard Language-
Dependent System Support;
and NIST FIPS 151-1.
(printed 6/20/89)