On booting, a memory/RAM file system for the writeable directories (
mount_mfs(8)) will be newly (re)created/formatted.
mount_mfs is kind of an alias for
newfs. They share so much functionality that they are the same binary and are described in the same man page.
Code:
$ ls -li /sbin/{newfs,mount_mfs}
26020 -r-xr-xr-x 2 root bin 214224 Dec 21 2012 /sbin/mount_mfs
26020 -r-xr-xr-x 2 root bin 214224 Dec 21 2012 /sbin/newfs
These executables have the same inode, and one is thus a hard linked to the other.
From
mount_mfs(8)
Code:
NAME
newfs, mount_mfs - construct a new file system
With the
-P option you specify a directory or file system that on (re)boot will be copied to the the newly
newfsed file system.