The "physical layer" used for WLAN is more complicated than you think, it's actually several layers.
Out of the box, without hacking and modifying the firmware of a specific card, the lowest you can get is to capture packets with 802.11 headers, by enabling "monitor mode" in that driver (which usually will give you a second WLAN interface).
Wireshark can ...
This question is already answered
on superuser.com by sysadmin1138:
The filesystem itself, represented by the physical order of information on a storage-representation, is independent of the OS. The OS contains a driver that allows it to work with the filesystem. Some filesystems may only have one OS that can talk to it, and that OS has that filesystem ...
As all current file systems do not require the file to be stored in a continuous memory block,
Filesystems might not require files to be stored in a continuous area (and that would be very inflexible indeed), but usually files are stored in fixed-size blocks (or sequences of contiguous blocks). Doing it that way simplifies the implementation, and the blocks ...
On recent Linux systems that is actually possible, but with block (4096 most of the time), not byte granularity, and only on some filesystems (ext4 and xfs).
Quoting from the fallocate(2) manpage:
int fallocate(int fd, int mode, off_t offset, off_t len);
Collapsing file space
Specifying the FALLOC_FL_COLLAPSE_RANGE flag (available ...