1UMASK(3P)                  POSIX Programmer's Manual                 UMASK(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       umask - set and get the file mode creation mask
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SYNOPSIS

15       #include <sys/stat.h>
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17       mode_t umask(mode_t cmask);
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DESCRIPTION

21       The umask() function shall set the process' file mode creation mask  to
22       cmask  and return the previous value of the mask. Only the file permis‐
23       sion bits of cmask (see <sys/stat.h>) are  used;  the  meaning  of  the
24       other bits is implementation-defined.
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26       The  process'  file  mode creation mask is used during open(), creat(),
27       mkdir(), and mkfifo() to turn off permission bits in the mode  argument
28       supplied.  Bit  positions that are set in cmask are cleared in the mode
29       of the created file.
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RETURN VALUE

32       The file permission bits in the value returned by umask() shall be  the
33       previous  value  of the file mode creation mask. The state of any other
34       bits in that value is unspecified, except that  a  subsequent  call  to
35       umask()  with  the returned value as cmask shall leave the state of the
36       mask the same as its state before the first call, including any unspec‐
37       ified use of those bits.
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ERRORS

40       No errors are defined.
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42       The following sections are informative.
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EXAMPLES

45       None.
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APPLICATION USAGE

48       None.
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RATIONALE

51       Unsigned  argument  and  return  types  for umask() were proposed.  The
52       return type and the argument were both changed to mode_t.
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54       Historical implementations have made use of additional  bits  in  cmask
55       for  their  implementation-defined  purposes.  The addition of the text
56       that the meaning of other bits of the field  is  implementation-defined
57       permits   these   implementations   to   conform   to  this  volume  of
58       IEEE Std 1003.1-2001.
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FUTURE DIRECTIONS

61       None.
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SEE ALSO

64       creat(), mkdir(), mkfifo(), open(),  the  Base  Definitions  volume  of
65       IEEE Std 1003.1-2001, <sys/stat.h>, <sys/types.h>
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68       Portions  of  this text are reprinted and reproduced in electronic form
69       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
70       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
71       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
72       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
73       event of any discrepancy between this version and the original IEEE and
74       The  Open Group Standard, the original IEEE and The Open Group Standard
75       is the referee document. The original Standard can be  obtained  online
76       at http://www.opengroup.org/unix/online.html .
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80IEEE/The Open Group                  2003                            UMASK(3P)
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