NAME
efivar —
UEFI environment variable
interaction
SYNOPSIS
efivar |
[-abdDHlLNpRtw] [-n
name] [-f
file] [--append]
[--ascii] [--attributes]
[--binary] [--delete]
[--fromfile file]
[--hex] [--list-guids]
[--list] [--name
name] [--no-name]
[--print]
[--print-decimal]
[--raw-guid] [--write]
name[=value] |
DESCRIPTION
This program manages “Unified Extensible Firmware Interface” (UEFI) environment variables. UEFI variables have three part: A namespace, a name and a value. The namespace is a GUID that is self assigned by the group defining the variables. The name is a Unicode name for the variable. The value is binary data. All Unicode data is presented to the user as UTF-8.The following options are available:
-nname--namename- Specify the name of the variable to operate on. The
name argument is the GUID of the variable, followed
by a dash, followed by the UEFI variable name. The GUID may be in numeric
format, or may be one of the well known symbolic name (see
--list-guidsfor a complete list). -ffile--fromfilefile- When writing or appending to a variable, take the data for the variable's
value from file instead of from the command line.
This flag implies
--writeunless the--appendflag is given. This behavior is not well understood and currently unimplemented. -a--append- Append the specified value to the UEFI variable rather than replacing it.
-tattr--attributesattr- Specify, in hexadecimal, the attributes for this variable. See section 7.2 (GetVariable subsection, Related Definitions) of the UEFI Specification for hex values to use.
-A--ascii- Display the variable data as modified ascii: All printable characters are printed, while unprintable characters are rendered as a two-digit hexadecimal number preceded by a % character.
-b--binary- Display the variable data as binary data. Usually will be used with the
-Nor--no-nameflag. Useful in scripts. -D--delete- Delete the specified variable. May not be used with either the
--writeor the--appendflags. No value may be specified. -H--hex- List variable data as a hex dump.
-L--list-guids- Lists the well known GUIDs. The names listed here may be used in place of
the numeric GUID values. These names will replace the numeric GUID values
unless
--raw-guidflag is specified. -l--list- List all the variables. If the
--printflag is also listed, their values will be displayed. -N--no-name- Do not display the variable name.
-p--print- Print the value of the variable.
-d--print-decimal- Treat the value of the variable as a number and print it as a decimal. This is currently unimplemented.
-R--raw-guid- Do not substitute well known names for GUID numeric values in output.
-w--write- Write (replace) the variable specified with the value specified.
- name
- Display the name environment variable.
- name=value
- Set the specified name to value. This is not yet implemented.
COMPATIBILITY
The efivar program is intended to be
compatible (strict superset) with a program of the same name included in the
Red Hat libefivar package.
SEE ALSO
Appendix A of the UEFI specification has the format for GUIDs. All GUIDs (“Globally Unique Identifiers”) have the format described in RFC 4122.