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Is there any way to find the physical address of a file if the path is provided?

Devika M J
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    Welcome to the site. Could you explain what exactly you mean by "memory address"? – AdminBee Apr 20 '20 at 14:33
  • Don't you think it's weird to say "memory address" of a file on disk ? – 炸鱼薯条德里克 Apr 20 '20 at 15:17
  • Sorry , I made a mistake.I mean the physical address of a file – Devika M J Apr 20 '20 at 15:50
  • That's possible on Linux with the FIBMAP ioctl (combined with FIGETBSZ). Most filesystems support it. I know that boot loaders like lilo and grub are using it when setting up their 2nd or 3rd stage, but I'm not aware of any readily available utility making use of it. –  Apr 20 '20 at 16:03

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You can do that with hdparm --fibmap:

# hdparm --fibmap /var/log/messages

/var/log/messages:
 filesystem blocksize 4096, begins at LBA 360720384; assuming 512 byte sectors.
 byte_offset  begin_LBA    end_LBA    sectors
           0  413190576  413190583          8
        4096  409598016  409598135        120
       65536  371059584  371059711        128
      131072  371060224  371060359        136
      200704  360802936  360803567        632
      524288  399259648  399260047        400
      729088  360797952  360798207        256
      860160  413419968  413420335        368
     1048576  413421568  413422199        632

# echo LOL >/tmp/lol
# hdparm --fibmap /tmp/lol

/tmp/lol:
 filesystem blocksize 4096, begins at LBA 360720384; assuming 512 byte sectors.
 byte_offset  begin_LBA    end_LBA    sectors
           0  413374584  413374591          8
# dd if=/dev/sda skip=413374584 count=8 status=none | hexdump -C
00000000  4c 4f 4c 0a 00 00 00 00  00 00 00 00 00 00 00 00  |LOL.............|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00001000

hdparm is making use of the FS_IOC_FIEMAP ioctl, and falls back to FIGETBSZ / FIBMAP if that's not available.