[Android]Recovery调用外部Shell脚本，Shell脚本使用ui_print方法

busybox_bin=/sbin/busybox

# 获取PIPE
get_outfd(){
    if $busybox_bin ls -l /proc/self/fd/21 | $busybox_bin grep -q 'pipe'; then
        echo 21
    else
        local all_pipe_file=/tmp/all_pipe_file.txt
        $busybox_bin ls -l /proc/self/fd/ > $all_pipe_file
        $busybox_bin grep 'pipe:' $all_pipe_file | $busybox_bin awk '{print $9}'
    fi
}

OUTFD=$(get_outfd)

# 打印日志
ui_print(){
    if $busybox_bin test -n $OUTFD;then 
        echo -n -e "ui_print $1
" > /proc/self/fd/$OUTFD
        echo -n -e "ui_print
" > /proc/self/fd/$OUTFD
    fi
}

ui_print "Iam here!!!"

在Shell脚本中可以使用ui_print可以方便调试Recovery环境运行的Shell脚本，也可以向用户提供关键的日志信息