bsd/man/man2/umask.2

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  34 .\"     @(#)umask.2     8.1 (Berkeley) 6/4/93
  35 .\"
  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/stat.h>
  44 .Ft mode_t
  45 .Fo umask
  46 .Fa "mode_t cmask"
  47 .Fc
  48 .Sh DESCRIPTION
  49 The
  50 .Fn umask
  51 routine sets the process's file mode creation mask to
  52 .Fa cmask
  53 and returns the previous value of the mask.
  54 The 9 low-order access permission bits of
  55 .Fa cmask
  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 LEGACY SYNOPSIS
  79 .Fd #include <sys/types.h>
  80 .Fd #include <sys/stat.h>
  81 .Pp
  82 The include file
  83 .In sys/types.h
  84 is necessary.
  85 .Sh SEE ALSO
  86 .Xr chmod 2 ,
  87 .Xr mkdir 2 ,
  88 .Xr mkfifo 2 ,
  89 .Xr mknod 2 ,
  90 .Xr open 2 ,
  91 .Xr compat 5
  92 .Sh STANDARDS
  93 The
  94 .Fn umask
  95 function call is expected to
  96 conform to
  97 .St -p1003.1-88 .