How to replace and sync(on the fly) EFS partitions via Termux instead of Fastboot or Recovery?

I have backup of my EFS partitions in raw and also in .Img format. So now i want to: 1. replace my current EFS partitions via Termux/Terminal emulator app. 2. replaced EFS should also sync with modem without any reboot. **I have successfully done above via Fastboot and Recovery but that i don't want to.** **My Findings:** I found EFS and modem partitions are mounted as modemst1, modemst2, modem and fsg etc in /dev/block/ and /dev/block/by-name. But replacing them via Termux won't make any difference to actual EFS partitions. Also after reboot these again gets re-created/replaced. But if i replace all these partitons via Recovery/Fastboot then it make actual permanent changes to EFS partitions and sync with modem and also sustain reboot.