root@localhost:/boot/uboot# cat /etc/fw_env.config 
/boot/uboot/uboot.env 0x0000 0x4000
root@localhost:/boot/uboot# cat /etc/fw_env.config 
/boot/uboot/uboot.env 0x0000 0x4000
root@localhost:/boot/uboot# fw_setenv foo bar
root@localhost:/boot/uboot# fw_getenv foo 
bash: fw_getenv: command not found
root@localhost:/boot/uboot# fw_printenv foo |grep foo
foo=bar
root@localhost:/boot/uboot# cat uboot.env |grep foo
Binary file (standard input) matches
root@localhost:/boot/uboot# cat uboot.env |grep foo=bar
Binary file (standard input) matches
root@localhost:/boot/uboot# ls -l uboot.env 
-rwxr-xr-x 1 root root 16384 Jul 16 10:28 uboot.env