Section: POSIX Programmer's Manual (3P)
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
--- set and get the file mode creation mask
mode_t umask(mode_t cmask);
function shall set the file mode creation mask of the process to
and return the previous value of the mask. Only the file permission
are used; the meaning of the other bits is implementation-defined.
The file mode creation mask of the process is used to turn off
permission bits in the
argument supplied during calls to the following functions:
Bit positions that are set in
are cleared in the mode of the created file.
The file permission bits in the value returned by
shall be the previous value of the file mode creation mask. The state
of any other bits in that value is unspecified, except that a
subsequent call to
with the returned value as
shall leave the state of the mask the same as its state before the
first call, including any unspecified use of those bits.
No errors are defined.
The following sections are informative.
Unsigned argument and return types for
were proposed. The return type and the argument were both changed to
Historical implementations have made use of additional bits in
for their implementation-defined purposes. The addition of the text
that the meaning of other bits of the field is implementation-defined
permits these implementations to conform to this volume of POSIX.1-2008.
The Base Definitions volume of POSIX.1-2008,
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
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