How to confirm ready state for an external USB disk before attempting other actions

[start of edit 1] Before I plug in my external USB backup drive , my computer is fully booted-up, and I am in my session as root. Because of its location, my USB cord is already plugged in, but I manually plug in my power cord for the drive when I need it. [end of edit 1] I have routines for mounting the multiple partitions found on an external USB3 MyBook hard drive. I have not had any issues in having the partitions mount because after plugging in my USB drive, I hold my hand on the drive to feel when the Linux initiation routines are done by choosing when I no longer sense the vibration fro

Question by Eric Marceau on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.