1.\" 2.\" Copyright (c) 2017-2021 Netflix, Inc. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd April 7, 2021 28.Dt EFIVAR 8 29.Os 30.Sh NAME 31.Nm efivar 32.Nd UEFI environment variable interaction 33.Sh SYNOPSIS 34.Nm 35.Op Fl abdDHlLNpqRtuw 36.Op Fl n Ar name 37.Op Fl f Ar file 38.Op Fl -append 39.Op Fl -ascii 40.Op Fl -attributes 41.Op Fl -binary 42.Op Fl -delete 43.Op Fl -device-path 44.Op Fl -fromfile Ar file 45.Op Fl -guid 46.Op Fl -hex 47.Op Fl -list-guids 48.Op Fl -list 49.Op Fl -load-option 50.Op Fl -name Ar name 51.Op Fl -no-name 52.Op Fl -print 53.Op Fl -print-decimal 54.Op Fl -quiet 55.Op Fl -raw-guid 56.Op Fl -utf8 57.Op Fl -write 58.Sh DESCRIPTION 59This program manages 60.Dq Unified Extensible Firmware Interface 61.Pq UEFI 62environment variables. 63UEFI variables have three parts: A namespace, a name and a value. 64The namespace is a GUID that is self assigned by the group defining the 65variables. 66The name is a Unicode name for the variable. 67The value is binary data. 68All Unicode data is presented to the user as UTF-8. 69.Pp 70The following options are available: 71.Bl -tag -width 20m 72.It Fl n Ar name Fl -name Ar name 73Specify the name of the variable to operate on. 74The 75.Ar name 76argument is the GUID of the variable, followed by a dash, followed by the 77UEFI variable name. 78The GUID may be in numeric format, or may be one of the well known 79symbolic names (see 80.Fl -list-guids 81for a complete list). 82.It Fl f Ar file Fl -fromfile Ar file 83When writing or appending to a variable, take the data for the 84variable's value from 85.Ar file 86instead of from the command line. 87This flag implies 88.Fl -write 89unless the 90.Fl -append 91or 92.Fl -print 93flags are given. 94This behavior is not well understood and is currently unimplemented 95for writes. 96When 97.Fl -print 98is specified, the contents of the file are used as the value to 99print using any other specified flags. 100This is used primarily for testing purposes for more complicated 101variable decoding. 102.It Fl a Fl -append 103Append the specified value to the UEFI variable rather than replacing 104it. 105.It Fl t Ar attr Fl -attributes Ar attr 106Specify, in hexadecimal, the attributes for this 107variable. 108See section 7.2 (GetVariable subsection, Related Definitions) of the 109UEFI Specification for hex values to use. 110.It Fl A Fl -ascii 111Display the variable data as modified ASCII: All printable characters 112are printed, while unprintable characters are rendered as a two-digit 113hexadecimal number preceded by a % character. 114.It Fl b Fl -binary 115Display the variable data as binary data. 116Usually will be used with the 117.Fl N 118or 119.Fl -no-name 120flag. 121Useful in scripts. 122.It Fl D Fl -delete 123Delete the specified variable. 124May not be used with either the 125.Fl -write 126or the 127.Fl -append 128flags. 129No 130.Ar value 131may be specified. 132.It Fl d Fl -device Fl -device-path 133Interpret the variables printed as UEFI device paths and print the 134UEFI standard string representation. 135.It Fl g Fl -guid 136Convert GUIDs to names if they are known 137.Po and show them in 138.Fl -list-guids 139.Pc . 140.It Fl H Fl -hex 141List variable data as a hex dump. 142.It Fl L Fl -list-guids 143Lists the well known GUIDs. 144The names listed here may be used in place of the numeric GUID values. 145These names will replace the numeric GUID values unless the 146.Fl -raw-guid 147flag is specified. 148.It Fl l Fl -list 149List all the variables. 150If the 151.Fl -print 152flag is also listed, their values will be displayed. 153.It Fl -load-option 154Decode the variable as if it were a UEFI Boot Option, including information 155about what device and/or paths the UEFI DevicePaths decode to. 156.It Fl N Fl -no-name 157Do not display the variable name. 158.It Fl p Fl -print 159Print the value of the variable. 160.It Fl q Fl -quiet 161When an error occurs, exit with a non-zero value without outputting 162any error messages. 163Otherwise, produce the normal output and exit with a zero status. 164.It Fl R Fl -raw-guid 165Do not substitute well known names for GUID numeric values in output. 166.It Fl u Fl -utf8 167Treat the value of the variable as UCS2 and convert it to UTF8 and 168print the result. 169.It Fl w Fl -write 170Write (replace) the variable specified with the value specified from 171standard input. 172No command line option to do this is available since UEFI variables 173are binary structures rather than strings. 174.Xr echo 1 175.Fl n 176can be used to specify simple strings. 177.It Ar name 178Display the 179.Ar name 180environment variable. 181.El 182.Sh COMPATIBILITY 183The 184.Nm 185program is intended to be compatible (strict superset) with a program 186of the same name included in the Red Hat libefivar package, 187but the 188.Fl d 189and 190.Fl -print-decimal 191flags are not implemented and never will be. 192.Pp 193The 194.Fl d 195flag is short for 196.Fl -device-path . 197.Sh SEE ALSO 198Appendix A of the UEFI specification has the format for GUIDs. 199All GUIDs 200.Dq Globally Unique Identifiers 201have the format described in RFC 4122. 202.Sh HISTORY 203The 204.Nm 205utility first appeared in 206.Fx 11.1 . 207