bsd/man/man2/umask.2

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  34 .\"     @(#)umask.2     8.1 (Berkeley) 6/4/93
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  36 .Dd June 4, 1993
  37 .Dt UMASK 2
  38 .Os BSD 4
  39 .Sh NAME
  40 .Nm umask
  41 .Nd set file creation mode mask
  42 .Sh SYNOPSIS
  43 .Fd #include <sys/types.h>
  44 .Fd #include <sys/stat.h>
  45 .Ft mode_t
  46 .Fn umask "mode_t numask"
  47 .Sh DESCRIPTION
  48 The
  49 .Fn umask
  50 routine sets the process's file mode creation mask to
  51 .Fa numask
  52 and returns the previous value of the mask.  The 9 low-order
  53 access permission
  54 bits of
  55 .Fa numask
  56 are used by system calls, including
  57 .Xr open 2 ,
  58 .Xr mkdir 2 ,
  59 .Xr mkfifo 2
  60 and
  61 .Xr mknod 2
  62 to turn off corresponding bits
  63 requested in file mode.
  64 (See
  65 .Xr chmod 2 ) .
  66 This clearing allows each user to restrict the default access
  67 to his files.
  68 .Pp
  69 The default mask value is S_IWGRP|S_IWOTH (022, write access for the
  70 owner only).
  71 Child processes inherit the mask of the calling process.
  72 .Sh RETURN VALUES
  73 The previous value of the file mode mask is returned by the call.
  74 .Sh ERRORS
  75 The
  76 .Fn umask
  77 function is always successful.
  78 .Sh SEE ALSO
  79 .Xr chmod 2 ,
  80 .Xr mkdir 2 ,
  81 .Xr mkfifo 2 ,
  82 .Xr mknod 2 ,
  83 .Xr open 2
  84 .Sh STANDARDS
  85 The
  86 .Fn umask
  87 function call is expected to
  88 conform to
  89 .St -p1003.1-88 .