2.9BSD/usr/man/man2/creat.2

.TH CREAT 2 
.UC
.SH NAME
creat  \-  create a new file
.SH SYNOPSIS
.B creat(name, mode)
.br
.B char *name;
.SH DESCRIPTION
.I Creat
creates a new file or prepares to rewrite an existing
file called 
.I name,
given as the address of a null-terminated string.
If the file did not exist, it is given
mode
.IR mode ,
as modified by the process's mode mask (see
.IR umask (2)).
Also see
.IR  chmod (2)
for the
construction of the
.I mode
argument.
.PP
If the file did exist, its mode and owner remain unchanged
but it is truncated to 0 length.
.PP
The file is also opened for writing, and its file descriptor
is returned.
.PP
The
.I mode
given is arbitrary; it need not allow
writing.
This feature is used by programs which deal with temporary
files of fixed names.
The creation is done with
a mode that forbids writing.
Then if a second
instance of the program attempts a
.I creat,
an error is
returned and the program knows that the name is unusable
for the moment.
.SH RETURN VALUE
Upon successful completion, a value of 0 is returned.  Otherwise, a
value of \-1 is returned and
.I errno
is set to indicate the error.
.SH ERRORS
.I Creat
will fail and the file will not be created if:
.TP 20
[EINVAL]
The path name contains a non-ASCII byte.
.TP 20
[ENOTDIR]
A component of the path prefix is not a directory.
.TP 20
[EACCES]
A component of the path prefix denies search permission.
.TP 20
[EACCES]
The directory in which the file is to be created is not writeable by
the user.
.TP 20
[EISDIR]
The named file is a directory.
.TP 20
[EROFS]
The directory in which the file is to be created is on a read-only
file system.
.TP 20
[EMFILE]
The maximum number of file descriptors allowed are already open.
.TP 20
[ETXTBSY]
The file is a pure procedure (shared text) file that is being executed.
.TP 20
[EQUOT]
The disk quota for the directory in which the file was
to be created would have been exceeded.
.TP 20
[EFAULT]
.I Name
points outside the process's allocated address space.
.TP 20
[ELOOP]
Too many symbolic links were encountered in translating the path name.
.SH "SEE ALSO"
chmod(2), close(2), umask(2), write(2)
.SH ASSEMBLER
(creat = 8.)
.br
.B sys creat; name; mode
.br
(file descriptor in r0)