The package u-boot-linux-utils provides a Linux utility for accessing the U-Boot environment. The utility provided with U-Boot in version 1.3.4 does not work with NAND flash. This utility is meant as an alternative to U-Boot’s fw_{print,set}env.

$ u-boot
Usage: u-boot { printenv [ name ] | setenv name [ value ] }

$ u-boot printenv test
environment variable not found
$ u-boot setenv test me
$ u-boot printenv test
test=me