nvram(8)

NAME
nvram - manipulate Open Firmware NVRAM variables

SYNOPSIS
nvram [ -p ] [ -f filename ] [ name ] [= value ] ...

DESCRIPTION
The nvram command allows manipulation of Open 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.

In principle, name can be any string. In practice, not all strings will be accepted. Old world machines have a fixed set of Open Firmware variables. New World machines can create new variables as desired. Some variables require administrator privilege to get or set.

The given value must match the data type required for 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.

Two Open Firmware variables have special treatment on old world machines: boot-command and boot-args. As long as boot-command starts with "# bootr," the boot-args variable will be present. Getting or setting boot-args will get or set the boot-command while preserving the "# bootr". In most cases when setting boot arguments for the kernel, there is no need to test for old world and set boot-command. Instead set boot-args with the desired arguments.

OPTIONS

-p  Print all of the Open Firmware variables.

-f filename
    Set Open 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.

EXAMPLES

    example% nvram boot-args="-s rd=*hd:10"

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.

    example% nvram my-variable="String One%00String Two%00%00"

Create a new variable, my-variable, containing a list of two C-strings that is terminated by a NUL.

FILES
/usr/share/nvram
    Files containing patches for old world machines.