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.Dd April 7, 2021 26.Dt EFIVAR 8 27.Os 28.Sh NAME 29.Nm efivar 30.Nd UEFI environment variable interaction 31.Sh SYNOPSIS 32.Nm 33.Op Fl abdDHlLNpqRtuw 34.Op Fl n Ar name 35.Op Fl f Ar file 36.Op Fl -append 37.Op Fl -ascii 38.Op Fl -attributes 39.Op Fl -binary 40.Op Fl -delete 41.Op Fl -device-path 42.Op Fl -fromfile Ar file 43.Op Fl -guid 44.Op Fl -hex 45.Op Fl -list-guids 46.Op Fl -list 47.Op Fl -load-option 48.Op Fl -name Ar name 49.Op Fl -no-name 50.Op Fl -print 51.Op Fl -print-decimal 52.Op Fl -quiet 53.Op Fl -raw-guid 54.Op Fl -utf8 55.Op Fl -write 56.Sh DESCRIPTION 57This program manages 58.Dq Unified Extensible Firmware Interface 59.Pq UEFI 60environment variables. 61UEFI variables have three parts: A namespace, a name and a value. 62The namespace is a GUID that is self assigned by the group defining the 63variables. 64The name is a Unicode name for the variable. 65The value is binary data. 66All Unicode data is presented to the user as UTF-8. 67.Pp 68The following options are available: 69.Bl -tag -width 20m 70.It Fl n Ar name Fl -name Ar name 71Specify the name of the variable to operate on. 72The 73.Ar name 74argument is the GUID of the variable, followed by a dash, followed by the 75UEFI variable name. 76The GUID may be in numeric format, or may be one of the well known 77symbolic names (see 78.Fl -list-guids 79for a complete list). 80.It Fl f Ar file Fl -fromfile Ar file 81When writing or appending to a variable, take the data for the 82variable's value from 83.Ar file 84instead of from the command line. 85This flag implies 86.Fl -write 87unless the 88.Fl -append 89or 90.Fl -print 91flags are given. 92This behavior is not well understood and is currently unimplemented 93for writes. 94When 95.Fl -print 96is specified, the contents of the file are used as the value to 97print using any other specified flags. 98This is used primarily for testing purposes for more complicated 99variable decoding. 100.It Fl a Fl -append 101Append the specified value to the UEFI variable rather than replacing 102it. 103.It Fl t Ar attr Fl -attributes Ar attr 104Specify, in hexadecimal, the attributes for this 105variable. 106See section 7.2 (GetVariable subsection, Related Definitions) of the 107UEFI Specification for hex values to use. 108.It Fl A Fl -ascii 109Display the variable data as modified ASCII: All printable characters 110are printed, while unprintable characters are rendered as a two-digit 111hexadecimal number preceded by a % character. 112.It Fl b Fl -binary 113Display the variable data as binary data. 114Usually will be used with the 115.Fl N 116or 117.Fl -no-name 118flag. 119Useful in scripts. 120.It Fl D Fl -delete 121Delete the specified variable. 122May not be used with either the 123.Fl -write 124or the 125.Fl -append 126flags. 127No 128.Ar value 129may be specified. 130.It Fl d Fl -device Fl -device-path 131Interpret the variables printed as UEFI device paths and print the 132UEFI standard string representation. 133.It Fl g Fl -guid 134Convert GUIDs to names if they are known 135.Po and show them in 136.Fl -list-guids 137.Pc . 138.It Fl H Fl -hex 139List variable data as a hex dump. 140.It Fl L Fl -list-guids 141Lists the well known GUIDs. 142The names listed here may be used in place of the numeric GUID values. 143These names will replace the numeric GUID values unless the 144.Fl -raw-guid 145flag is specified. 146.It Fl l Fl -list 147List all the variables. 148If the 149.Fl -print 150flag is also listed, their values will be displayed. 151.It Fl -load-option 152Decode the variable as if it were a UEFI Boot Option, including information 153about what device and/or paths the UEFI DevicePaths decode to. 154.It Fl N Fl -no-name 155Do not display the variable name. 156.It Fl p Fl -print 157Print the value of the variable. 158.It Fl q Fl -quiet 159When an error occurs, exit with a non-zero value without outputting 160any error messages. 161Otherwise, produce the normal output and exit with a zero status. 162.It Fl R Fl -raw-guid 163Do not substitute well known names for GUID numeric values in output. 164.It Fl u Fl -utf8 165Treat the value of the variable as UCS2 and convert it to UTF8 and 166print the result. 167.It Fl w Fl -write 168Write (replace) the variable specified with the value specified from 169standard input. 170No command line option to do this is available since UEFI variables 171are binary structures rather than strings. 172.Xr echo 1 173.Fl n 174can be used to specify simple strings. 175.It Ar name 176Display the 177.Ar name 178environment variable. 179.El 180.Sh COMPATIBILITY 181The 182.Nm 183program is intended to be compatible (strict superset) with a program 184of the same name included in the Red Hat libefivar package, 185but the 186.Fl d 187and 188.Fl -print-decimal 189flags are not implemented and never will be. 190.Pp 191The 192.Fl d 193flag is short for 194.Fl -device-path . 195.Sh SEE ALSO 196Appendix A of the UEFI specification has the format for GUIDs. 197All GUIDs 198.Dq Globally Unique Identifiers 199have the format described in RFC 4122. 200.Sh HISTORY 201The 202.Nm 203utility first appeared in 204.Fx 11.1 . 205