creat(2) creat(2)
NAME
creat - create a new file or rewrite an existing one
SYNOPSIS
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int creat(const char *path, mode_t mode);
DESCRIPTION
creat 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.
If the file does not exist the file's owner ID is set to the
effective user ID of the process. The group ID of the file is set to
the effective group ID of the process, or if the S_ISGID bit is set
in the parent directory then the group ID of the file is inherited
from the parent directory. The access permission bits of the file
mode are set to the value of mode modified as follows:
If the group ID of the new file does not match the effective
group ID or one of the supplementary group IDs, the S_ISGID bit
is cleared.
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) for the values of mode].
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(2)]. A new file may be created with a mode that forbids
writing.
The call creat(path, mode) is equivalent to:
open(path, O_WRONLY | O_CREAT | O_TRUNC, mode)
creat fails if one or more of the following are true:
EACCES Search permission is denied on a component of the
path prefix.
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creat(2) creat(2)
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, mandatory file/record locking is
set, and there are outstanding record locks on
the file [see chmod(2)].
EFAULT path points outside the allocated address space
of the process.
EISDIR The named file is an existing directory.
EINTR A signal was caught during the creat system call.
ELOOP Too many symbolic links were encountered in
translating path.
EMFILE The process has too many open files [see
getrlimit(2)].
ENAMETOOLONG The length of the path argument exceeds
{PATH_MAX}, or the length of a path component
exceeds {NAME_MAX} while _POSIX_NO_TRUNC is in
effect.
ENOTDIR A component of the path prefix is not a
directory.
ENOENT A component of the path prefix does not exist.
ENOENT The path name is null.
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.
ENFILE The system file table is full.
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.
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creat(2) creat(2)
ENOSPC The file system is out of inodes.
SEE ALSO
chmod(2), close(2), dup(2), fcntl(2), getrlimit(2), lseek(2),
open(2), read(2), umask(2), write(2), stat(5).
DIAGNOSTICS
Upon successful completion a non-negative integer, namely the lowest
numbered unused file descriptor, is returned. Otherwise, a value of
-1 is returned, no files are created or modified, and errno is set to
indicate the error.
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