NAME
creat — create a new file or rewrite an existing one
SYNOPSIS
#include <fcntl.h>
int creat(const char *path, mode_t mode);
DESCRIPTION
The
creat()
system call creates a new regular file
or prepares to rewrite an existing file
named by the path name pointed to by
path.
If the file exists, its length is truncated to 0, and its mode
and owner are unchanged.
Otherwise, the file's owner ID
is set to the effective user ID of the process.
If the set-group-ID bit of the parent directory is set,
the file's group ID is set to the group ID of the parent directory.
Otherwise, the file's group ID is set to the process's effective group ID.
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(2)).
The "save text image after execution" bit of the mode is cleared
(see
chmod(2)).
If the system call is made in 64 bit mode, the
O_LARGEFILE
status flag
is automatically set
(see
fcntl(5)
or
open(2)).
Upon successful completion, the file descriptor is returned
and the file is open for writing (only), even if the
mode
does not permit writing.
The file offset is set to the beginning of the file.
The file descriptor is set to remain open across
exec*()
system calls (see
fcntl(2)).
Each process has a limit on how many files it can open simultaneously.
Refer to
getrlimit(2)
for the open files limit.
This is also discussed in
open(2).
A new file can be created with a mode that forbids writing.
Access Control Lists - HFS File Systems Only
On HFS file systems that support access control lists, three base ACL
entries are created corresponding to the file access permission bits.
An existing file's access control list is unchanged by
creat()
(see
setacl(2),
chmod(2),
and
acl(5)).
Access Control Lists - JFS File Systems Only
On JFS file systems that support access control lists, optional ACL
entries are created corresponding to the parent directory's default
ACL entries. An existing file's access control list is unchanged by
creat()
(see
acl(2),
chmod(2),
and
aclv(5)).
RETURN VALUE
creat()
returns the following values:
- n
Successful completion.
n
is the value of the file descriptor.
It is nonnegative.
- -1
Failure.
errno
is set to indicate the error.
ERRORS
If
creat()
fails,
errno
is set to one of the following values:
- EACCES
Search permission is denied on a component of the path prefix.
- EACCES
The file does not exist and the directory in which the file
is to be created does not permit writing.
- EACCES
The file exists and write permission is denied.
- EAGAIN
The file exists, enforcement mode file and record locking is set and
there are outstanding record locks on the file.
- EDQUOT
User's or group's disk quota block or inode limit
has been reached for this file system.
- EFAULT
path
points outside the allocated address space of the process.
The reliable detection of this error is implementation dependent.
- EISDIR
The named file is an existing directory.
- ELOOP
Too many symbolic links were encountered in translating the path name.
- EMFILE
More than the maximum number of file descriptors are currently open.
- ENAMETOOLONG
The length of the specified path name exceeds
PATH_MAX
bytes, or the length of a component of the path name exceeds
NAME_MAX
bytes while
_POSIX_NO_TRUNC
is in effect.
- ENFILE
The system file table is full.
- ENOENT
The named file does not exist (for example,
path
is null, or a component of
path
does not exist).
- ENOSPC
Not enough space on the file system.
- ENOTDIR
A component of the path prefix is not a directory.
- ENXIO
The named file is a character special or block special file,
and the device associated with this special file does not exist.
- EOVERFLOW
The named file is a regular file and the size of the file cannot
be represented correctly in an object of type
off_t.
- 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.
SEE ALSO
chmod(2),
close(2),
creat64(2),
dup(2),
fcntl(2),
lockf(2),
lseek(2),
open(2),
open64(2),
read(2),
setacl(2),
truncate(2),
umask(2),
write(2),
acl(5),
aclv(5),
privileges(5).
STANDARDS CONFORMANCE
creat(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1
Printable version
