NAME¶

apex-env - user-mode access to APEX flash environment

SYNOPSIS¶

apex-env COMMAND [ ARGS ... ]

DESCRIPTION¶

apex-env is a utility for viewing and modifying the environment used by the APEX Boot Loader to define how the system will boot. APEX has a predefined set of environment variables, determined by the build-time configuration, that control operation of the boot loader.

Embedded in the APEX image is a linking structure that apex-env uses to identify the boot loader image and to locate information about the environment variables as well as the flash region that holds the user-modified values. If APEX is built without enabling this user-modifiable flash region, apex-env will only allow the user to browse the variables and the default values.

apex-env depends on the /dev/mtd driver to locate the APEX. It first looks for a partition named 'Loader', but it will also check the first partition in case APEX is used as the primary boot loader.

The user may need root privileges to run apex-env, even when only reading the environment.

COMMANDS¶

describe [KEY]

Displays a description of KEY or descriptions of every environment variable is KEY is omitted.

dump

Displays the contents of the flash environment region in a hexadecimal/ASCII format useful for troubleshooting.

eraseenv

Clears the environment region by setting all of the bytes to 0xff. Use this command with care. Assuming that APEX was properly built for your system, it still relies on the caching feature of the MTD block driver to modify only a portion of a flash eraseblock. Be mindful that interrupting this command after the block is erased and before the important data has been restored could render the system unbootable.

printenv [KEY]

Displays the value of KEY or the values of every environment variable if KEY is omitted. The separator between the key and the value is =* for default values or just = when the default value has been overridden by a value saved in the flash environment.

setenv KEY VALUE

Overrides the default value of KEY with VALUE. Use quoting to prevent the shell from splitting VALUE into separate words and from interpolation.

unsetenv KEY

Restores the default value of KEY by marking any value stored in flash as deleted.

EXAMPLES¶

apex-env printenv

Show all of the environment variables and the current values for each.

apex-env setenv startup 'copy $kernelsrc $bootaddr ; boot'

Change the startup variable to copy the kernel and immediately boot.

apex-env dump | head

Examine the first few bytes of the environment data.

AUTHOR¶

Marc Singer <elf@debian.org>