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.Dd September 29, 2016
.Dt EFIVAR 8
.Os
.Sh NAME
.Nm efivar
.Nd UEFI environemnt variable interaction
.Sh SYNOPSIS
.Nm
.Op Fl abdDHlLNpRtw
.Op Fl n Ar name
.Op Fl f Ar file
.Op Fl -append
.Op Fl -ascii
.Op Fl -attributes
.Op Fl -binary
.Op Fl -delete
.Op Fl -fromfile Ar file
.Op Fl -hex
.Op Fl -list-guids
.Op Fl -list
.Op Fl -name Ar name
.Op Fl -no-name
.Op Fl -print
.Op Fl -print-decimal
.Op Fl -raw-guid
.Op Fl -write
.Ar name Ns Op = Ns Ar value
.Sh DESCRIPTION
This program manages
.Dq Unified Extensible Firmware Interface
.Pq UEFI
environment variables.
UEFI variables have three part: A namespace, a name and a value.
The namespace is a GUID that's 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.
.Pp
The following options are available:
.Bl -tag -width 20m
.It Fl n Ar name Fl -name Ar name
Specify the name of the variable to operate on.
The
.Ar name
argument is the GUID of 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
.Fl -list-guids
for a complete list).
.It Fl f Ar file Fl -fromfile Ar file
When writing or appending to a variable, take the data for the
variable's value from
.Ar file
instead of from the command line.
This flag implies
.Fl -write
unless the
.Fl -append
flag is given.
This is not well understood and currently unimplemented.
.It Fl a Fl -append
Append the specified value to the UEFI variable rather than replacing
it.p
.It Fl t Ar attr Fl -attributes Ar attr
Specify, in user hostile hexidecimal, the attributes for this
variable.
See section 7.2 (GetVariable subsection, Related Definitions) of the
UEFI Specification for hex values to use.
.It Fl A Fl -ascii
Display the variable data as modified ascii: All printable characters
are printed, while unprintable characters are rendered as a two-digit
hexadecimal number preceeded by a % character.
.It Fl b Fl -binary
Display the variable data as binary data.
Usually will be used with the
.Fl N
or
.Fl -no-name
flag.
Useful in scripts.
.It Fl D Fl -delete
Delete the specified variable.
May not be used with either the
.Fl -write
or the
.Fl -append
flags.
No
.Ar value
may be specified.
.It Fl H Fl -hex
List variable data as a hex dump.
.It Fl L Fl -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
.Fl -raw-guid
flag is specified.
.It Fl l Fl -list
List all the variables.
If the
.Fl -print
flag is also listed, their values will be displayed.
.It Fl N Fl -no-name
Do not display the variable name.
.It Fl p Fl -print
Print the value of the variable.
.It Fl d Fl -print-decimal
Treat the value of the variable as a number and print it as a
decimal.
This is currently unimplemented.
.It Fl R Fl -raw-guid
Do not substitute well known names for GUID numeric values in output.
.It Fl w Fl -write
Write (replace) the variable specified with the value specified.
.It Ar name
Display the
.Ar name
environment variable.
.It Ar name Ns = Ns Ar value
Set the specified
.Ar name
to
.Ar value .
This is not yet implemented.
.Sh COMPATIBILITY
The
.Nm
program is intended to be compatible (strict superset) with a progam
of the same name included in the Red Hat libefivar package.
.Sh SEE ALSO
Appendix A of the UEFI specification has the format for GUIDs.
All GUIDs
.Dq Globally Unique Identifiers
have the format described in RFC 4122.
.El