env command

Synopsis

env ask name [message] [size]
env callbacks
env default [-f] (-a | var [...])
env delete [-f] var [...]
env edit name
env exists name
env export [-t | -b | -c] [-s size] addr [var ...]
env flags
env grep [-e] [-n | -v | -b] string [...]
env import [-d] [-t [-r] | -b | -c] addr [size] [var ...]
env info [-d] [-p] [-q]
env print [-a | name ...]
env print -e [-guid guid] [-n] [name ...]
env run var [...]
env save
env erase
env load
env select [target]
env set [-f] name [value]
env set -e [-nv][-bs][-rt][-at][-a][-i addr:size][-v] name [value]

Description

The env commands is used to handle the U-Boot (Environment Variables) or the UEFI variables.

The next commands are kept as alias and for compatibility:

editenv = env edit
grepenv = env grep
setenv = env set
askenv = env ask
run = env run

Ask

The env ask command asks for the new value of an environment variable (alias askenv command).

name
name of the environment variable.

message
message to be displayed while the command waits for the value to be entered from stdin. If no message is specified, a default message “Please enter name:” will be displayed.

size
maximum number of characters that will be stored in the environment variable name. This is in decimal number format (unlike in other commands where size values are hexa-decimal). The default value of size is 1023 (CONFIG_SYS_CBSIZE - 1).

Callbacks

The env callbacks command prints callbacks and their associated variables.

Default

The env default command resets the selected variables in the U-Boot environment to their default values.

var
list of variable name.

-a
all U-Boot environment.

-f
forcibly, overwrite read-only/write-once variables.

Delete

The env delete command deletes the selected variables from the U-Boot environment.

var
name of the variable to delete.

-f
forcibly, overwrite read-only/write-once variables.

Edit

The env edit command edits an environment variable.

name
name of the variable.

Exists

The env exists command tests for existence of variable.

name
name of the variable.

Export

The env export command exports the U-Boot environment in memory; on success, the variable $filesize will be set.

addr
memory address where environment gets stored.

var
list of variable names that get included into the export. Without arguments, the whole environment gets exported.

-b
export as binary format (name=value pairs separated by list end marked by double “00”).

-t
export as text format; if size is given, data will be padded with ‘0’ bytes; if not, one terminating ‘0’ will be added.

-c
Export as checksum protected environment format as used by ‘env save’ command.

-s size
size of output buffer.

Flags

The env flags command prints variables that have non-default flags.

Grep

The env grep command searches environment, list environment name=value pairs matching the requested ‘string’.

string
string to search in U-Boot environment.

-e
enable regular expressions.

-n
search string in variable names.

-v
search string in vairable values.

-b
search both names and values (default).

Import

The env import command imports environment from memory.

addr
memory address to read from.

size
length of input data; if missing, proper ‘0’ termination is mandatory if var is set and size should be missing (i.e. ‘0’ termination), set size to ‘-‘.

var
List of the names of the only variables that get imported from the environment at address ‘addr’. Without arguments, the whole environment gets imported.

-d
delete existing environment before importing if no var is passed; if vars are passed, if one var is in the current environment but not in the environment at addr, delete var from current environment; otherwise overwrite / append to existing definitions.

-t
assume text format; either “size” must be given or the text data must be ‘0’ terminated.

-r
handle CRLF like LF, that means exported variables with a content which ends with r won’t get imported. Used to import text files created with editors which are using CRLF for line endings. Only effective in addition to -t.

-b
assume binary format (’0’ separated, “00” terminated).

-c
assume checksum protected environment format.

Info

The env info command displays (without argument) or evaluates the U-Boot environment information.

-d
evaluate if the default environment is used.

-p
evaluate if environment can be persisted.

-q
quiet output, use only for command result, by example with ‘test’ command.

Print

The env print command prints the selected variables in U-Boot environment or in UEFI variables.

name
list of variable name.

-a
all U-Boot environment, when ‘name’ is absent.

-e
print UEFI variables, all by default when ‘name’.

-guid guid
print only the UEFI variables matching this GUID (any by default) with guid format = “xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx”.

-n
suppress dumping variable’s value for UEFI.

Run

The env run command runs commands in an environment variable.

var
name of the variable.

Save

The env save command saves the U-Boot environment in persistent storage.

Erase

The env erase command erases the U-Boot environment.

Load

The env load command loads the U-Boot environment from persistent storage.

Select

The env select command selects an U-Boot environment target, it is useful to overid the default location when several U-Boot environment backend are availables.

target
name of the U-Boot environment backend to select: EEPROM, EXT4, FAT, Flash, MMC, NAND, nowhere, NVRAM, OneNAND, Remote, SATA, SPIFlash, UBI.

Set

The env set command sets or delete (when ‘value’ or ‘-i’ are absent) U-Boot variable in environment or UEFI variables (when -e is specified).

name
variable name to modify.

value
when present, set the environment variable ‘name’ to ‘value’ when absent, delete the environment variable ‘name’.

-f
forcibly, overwrite read-only/write-once U-Boot variables.

-e
update UEFI variables.

-nv
set non-volatile attribute (UEFI).

-bs
set boot-service attribute (UEFI).

-rt
set runtime attribute (UEFI).

-at
set time-based authentication attribute (UEFI).

-a
append-write (UEFI).

-i addr:size
use <addr,size> as variable’s value (UEFI).

-v
verbose message (UEFI).

Example

Print the U-Boot environment variables:

=> env print -a
=> env print bootcmd stdout

Update environment variable in memory:

=> env set bootcmd "run distro_bootcmd"
=> env set stdout "serial,vidconsole"

Delete environment variable in memory:

=> env delete bootcmd
=> env set bootcmd

Reset environment variable to default value, in memory:

=> env default bootcmd
=> env default -a

Save current environment in persistent storage:

=> env save

Restore the default environment in persistent storage:

=> env erase

Create a text snapshot/backup of the current settings in RAM (${filesize} can be use to save the snapshot in file):

=> env export -t ${backup_addr}

Re-import this snapshot, deleting all other settings:

=> env import -d -t ${backup_addr}

Save environment if default enviromnent is used and persistent storage is selected:

=> if env info -p -d -q; then env save; fi

Configuration

The env command is always available but some sub-commands depend on configuration options:

ask: CONFIG_CMD_ASKENV
callback: CONFIG_CMD_ENV_CALLBACK
edit: CONFIG_CMD_EDITENV
exists: CONFIG_CMD_ENV_EXISTS
flags: CONFIG_CMD_ENV_FLAGS
erase: CONFIG_CMD_ERASEENV
export: CONFIG_CMD_EXPORTENV
grep: CONFIG_CMD_GREPENV, CONFIG_REGEX for ‘-e’ option
import: CONFIG_CMD_IMPORTENV
info: CONFIG_CMD_NVEDIT_INFO
load: CONFIG_CMD_NVEDIT_LOAD
run: CONFIG_CMD_RUN
save: CONFIG_CMD_SAVEENV
select: CONFIG_CMD_NVEDIT_SELECT
set, print: CONFIG_CMD_NVEDIT_EFI for ‘-e’ option