system_cmds-336.10.tar.gz

[apple/system_cmds.git] / nvram.tproj / nvram.8

.\"
.\" Copyright (c) 2000-2003 Apple Computer, Inc.  All rights reserved.
.\"
.TH nvram 8 "October 28, 2003"
.SH NAME
nvram \- manipulate firmware NVRAM variables
.SH SYNOPSIS
.B nvram
[
.B -p
] [
.B -f 
.IR filename
] [
.B -d 
.IR name
] [
.IR name
[=
.IR value
]] ...
.SH DESCRIPTION
The
.I nvram
command allows manipulation of firmware NVRAM variables.  It
can be used to get or set a variable.  It can also be used to print
all of the variables or set a list of variables from a file.
Changes to NVRAM variables are only saved by clean restart or shutdown.
.LP
In principle,
.IR name
can be any string.  In practice, not all strings will be accepted.
New World machines can create new variables as desired.  Some variables
require administrator privilege to get or set.
.LP
The given
.IR value
must match the data type required for
.IR name .
Binary data can be set using the %xx notation, where xx is the hex
value of the byte.  The type for new variables is always binary
data.
.SH OPTIONS
.TP
.B \-p
Print all of the firmware variables.
.TP
.BI \-f " filename"
Set firmware variables from a text file.  The file must be a
list name=value statements.  If the last character of a line is
\\, the value will be continued to the next line.
.TP
.BI \-d " name"
Deletes the named firmware variable.
.SH EXAMPLES
.LP
.RS
example% nvram boot-args="-s rd=*hd:10"
.RE
.LP
Set the boot-args variable to "-s rd=*hd:10".  This would specify
single user mode with the root device in hard drive partition 10.
.LP
.RS
example% nvram my-variable="String One%00String Two%00%00"
.RE
.LP
Create a new variable, my-variable, containing a list of two
C-strings that is terminated by a NUL.
.LP
.RS
example% nvram -d my-variable
.RE
.LP
Deletes the variable named my-variable.
.PD