[U-Boot] How to take value of an environmental variable of uboot in linux

Hi,

I type fw_printenv variable_name to take the name of a uboot variable from linux.

I get variable_name=10 for example

How can I use the value 10 in the continuation of my script?

I have tried

string = fw_printenv flag_boot_error IFS="=" read name value <<< $string

but it does not work

Thank you