V10/man/adm/man2/open.2

Compare this file to the similar file:
Show the results in this format: 

.TH OPEN 2
.CT 2 file_io
.SH NAME
open, creat, close \(mi open a file for reading or writing, create file
.SH SYNOPSIS
.nf
.B int open(file, rwmode)
.B char *file;
.PP
.B int creat(file, mode)
.B char *file;
.PP
.B int close(fildes)
.fi
.SH DESCRIPTION
.I Open
opens the
.I file,
for reading if
.I rwmode
is 0,
for writing if
.I rwmode
is 1,
or for both if
.I rwmode
is 2,
and returns an associated file descriptor.
.I File
is a null-terminated string representing
a path name.
The file pointer is set to 0.
.PP
.I Creat
creates a new
.I file
or prepares to rewrite an existing
.IR file ,
opens it for writing,
and returns an associated file descriptor.
If the file is new,
the owner is set to the effective userid of the creating process;
the group to that of the containing directory;
the mode to
.IR mode 
as modified by the mode mask of the creating process; see
.IR umask (2).
.I Mode
need not allow writing.
If the file already exists,
it is truncated to 0 length;
the mode, owner, and group remain unchanged,
and must permit writing.
.PP
A program may reserve a filename for exclusive use
by
calling
.I creat
with a mode that forbids writing.
If the file does not exist,
.I creat
will succeed;
further attempts to
.I creat
the same file will be denied.
More sophisticated
(but less portable)
concurrent access control
may be obtained by setting the
.B S_ICCTYP
field in the mode;
see
.IR stat (2).
.PP
.I Close
closes the file associated with a file descriptor.
Files are closed upon termination of a process,
but since
there is a limit on the number of open files per process,
.I close
is necessary for programs which deal with many files.
It is possible to arrange for files to be closed
by
.IR exec (2);
see
.B FIOCLEX
in
.IR ioctl (2).
.SH "SEE ALSO"
.IR dup (2),
.IR pipe (2), 
.IR read (2),
.IR exec (2), 
.IR ioctl (2),
.IR stat (2),
.IR unlink (2)
.SH DIAGNOSTICS
.IR "open, creat" :
.BR EACCES ,
.BR EBUSY ,
.BR ECONC ,
.BR EFAULT ,
.BR EINTR ,
.BR EIO ,
.BR EISDIR ,
.BR ELOOP ,
.BR EMFILE ,
.BR ENFILE ,
.BR ENOENT ,
.BR ENOTDIR ,
.BR EROFS ,
.BR ETXTBSY 
.br
.IR creat :
.BR ENOSPC
.br
.IR close:
.B EBADF
.SH BUGS
It should be possible to call
.I open
without waiting for carrier on communication lines.
.br
The group of a newly-created file should
(once again)
be the effective groupid of the creating process.
.br
The trick of creating a file with an unwritable mode
fails for the super-user.