nvram.tproj/nvram.8

   1 .\"
   2 .\" Copyright (c) 2000 Apple Computer, Inc.  All rights reserved.
   3 .\"
   4 .TH nvram 8 "December 12, 2000"
   5 .SH NAME
   6 nvram \- manipulate Open Firmware NVRAM variables
   7 .SH SYNOPSIS
   8 .B nvram
   9 [
  10 .B -p
  11 ] [
  12 .B -f
  13 .IR filename
  14 ] [
  15 .IR name
  16 ] [=
  17 .IR value
  18 ] ...
  19 .SH DESCRIPTION
  20 The
  21 .I nvram
  22 command allows manipulation of Open Firmware NVRAM variables.  It
  23 can be used to get or set a variable.  It can also be used to print
  24 all of the variables or set a list of variables from a file.
  25 .LP
  26 In principle,
  27 .IR name
  28 can be any string.  In practice, not all strings will be accepted.
  29 Old world machines have a fixed set of Open Firmware variables.
  30 New World machines can create new variables as desired.  Some variables
  31 require administrator privilege to get or set.
  32 .LP
  33 The given
  34 .IR value
  35 must match the data type required for
  36 .IR name .
  37 Binary data can be set using the %xx notation, where xx is the hex
  38 value of the byte.  The type for new variables is always binary
  39 data.
  40 .LP
  41 Two Open Firmware variables have special treatment on old world
  42 machines:
  43 .IR boot-command
  44 and
  45 .IR boot-args .
  46 As long as
  47 .IR boot-command
  48 starts with "# bootr," the
  49 .IR boot-args
  50 variable will be present.  Getting or setting
  51 .IR boot-args
  52 will get or set the
  53 .IR boot-command
  54 while preserving the "# bootr".  In most cases when setting boot arguments
  55 for the kernel, there is no need to test for old world and set
  56 .IR boot-command .
  57 Instead set
  58 .IR boot-args
  59 with the desired arguments.
  60 .SH OPTIONS
  61 .TP
  62 .B \-p
  63 Print all of the Open Firmware variables.
  64 .TP
  65 .BI \-f " filename"
  66 Set Open Firmware variables from a text file.  The file must be a
  67 list name=value statements.  If the last character of a line is
  68 \\, the value will be continued to the next line.
  69 .SH EXAMPLES
  70 .LP
  71 .RS
  72 example% nvram boot-args="-s rd=*hd:10"
  73 .RE
  74 .LP
  75 Set the boot-args variable to "-s rd=*hd:10".  This would specify
  76 single user mode with the root device in hard drive partition 10.
  77 .LP
  78 .RS
  79 example% nvram my-variable="String One%00String Two%00%00"
  80 .RE
  81 .LP
  82 Create a new variable, my-variable, containing a list of two
  83 C-strings that is terminated by a NUL.
  84 .SH FILES
  85 .PD 0
  86 .TP 30
  87 .B /usr/share/nvram
  88 Files containing patches for old world machines.
  89 .PD