On Tue, Nov 18, 2025 at 07:36:11PM +0100, Edgar Fu wrote: > > So, my first question would be, what precisely is it you're trying to > > prevent? > I want to prevent B to mount something on a temporary mount point already > in use by A. I.e., A sees the mount point is free, B sees it's free, > A mounts, B mounts, and A operates on the wrong thing. > > I have scripts that operate on snapshots they take. I.e., when I backup > /export/home, I look for an unused fss device, take an ffs snapshot of > /dev/dk5 on it, mount it, backup it, unmount, fssconfig -u. > The problem is I need a temporary mount point like /mnt which (highly > unlikely) could be in use by another (incarnation of the same) script. > Yes, I guess I could be using temporary entries in /tmp.
In this case I would probably create a dedicated directory such as /mnt_myscript, and for each invokation of the script have it always create a unique random mount point under that directory, use it for the duration of that particular run, then unlink it. I.E. never use /mnt_myscript directly, but only as a place to create a temporary mountpoint. Assuming that there are no other file sharing or locking issues, that potentially also allows multiple copies of the script to run simultaneously instead of erroring out.
