u-boot-utilite/u-boot-update-env.sh

#!/bin/bash

# This script will accept a text file with standard u-boot commands and 
# load it to the U-Boot environment. The original environment is saved
# in a backup file in the current directory

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
BACKUP_FILE=u-boot_env-$$.bak

if [ -z "$1" ]; then
    echo "Usage: $0 U-BOOT_ENV_FILE"
    exit 1
fi

# Backup existing U-Boot environment
env fw_printenv > $BACKUP_FILE || exit 2

# Check if the ethaddr variable is defined
ethaddr=$(fw_printenv ethaddr 2> /dev/null)

while read line
do
    # Suppress the ethaddr overwrite warning
    [ -z "$ethaddr"] && [[ "$line" =~ "ethaddr" ]] && continue

    # ignore comments starting with '#'
    if [[ "$line" == *'#'* ]]; then
        line=$(echo $line | cut -d\# -f1)
    fi

    if [[ $line  = *[^[:space:]]* ]]; then
        env fw_setenv $(echo $line | sed 's/=/ /') || exit 3
    fi
done < "$1"