u-boot/doc/usage/cmd/printenv.rst
Heinrich Schuchardt eaa268589e doc: man-page for the printenv command
Privide a man-page for the printenv command.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
2022-06-19 15:53:09 +02:00

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.. SPDX-License-Identifier: GPL-2.0+:
printenv command
================
Synopsis
--------
::
printenv [-a] [name ...]
printenv -e [-guid guid][-n] [name]
Description
-----------
The printenv command is used to print environment or UEFI variables.
\-a
Print environment variables starting with a period ('.').
\-e
Print UEFI variables. Without -e environment variables are printed.
\-guid *guid*
Specify vendor GUID *guid*. If none is specified, all UEFI variables with
the specified name are printed irrespective of their vendor GUID.
\-n
don't show hexadecimal dump of value
name
Variable name. If no name is provided, all variables are printed.
Multiple environment variable names may be specified.
Examples
--------
The following examples demonstrates the effect of the *-a* flag when displaying
environment variables:
::
=> setenv .foo bar
=> printenv
arch=sandbox
baudrate=115200
board=sandbox
...
stdout=serial,vidconsole
Environment size: 644/8188 bytes
=> printenv -a
.foo=bar
arch=sandbox
baudrate=115200
board=sandbox
...
stdout=serial,vidconsole
Environment size: 653/8188 bytes
=>
The next example shows the effect of the *-n* flag when displaying an UEFI
variable and how to specify a vendor GUID:
::
=> printenv -e -guid 8be4df61-93ca-11d2-aa0d-00e098032b8c PlatformLangCodes
PlatformLangCodes:
8be4df61-93ca-11d2-aa0d-00e098032b8c (EFI_GLOBAL_VARIABLE_GUID)
BS|RT|RO, DataSize = 0x6
00000000: 65 6e 2d 55 53 00 en-US.
=> printenv -e -n PlatformLangCodes
PlatformLangCodes:
8be4df61-93ca-11d2-aa0d-00e098032b8c (EFI_GLOBAL_VARIABLE_GUID)
BS|RT|RO, DataSize = 0x6
=>
Configuration
=============
UEFI variables are only supported if CONFIG_CMD_NVEDIT_EFI=y. The value of UEFI
variables can only be displayed if CONFIG_HEXDUMP=y.
Return value
------------
The return value $? is 1 (false) if a specified variable is not found.
Otherwise $? is set to 0 (true).