dumplfs —
dump file system information
  
    | dumplfs | [ -adiS] [-bblkno] [-Iblkno] [-ssegno] filesys
      | device | 
dumplfs prints out the file system layout information
  for the LFS file system or special device specified. The listing is very long
  and detailed. This command is useful mostly for finding out certain file
  system information such as the file system block size.
The following flags are interpreted by
    dumplfs.
  - -a
- Dump the contents of all superblocks, not just the first. Superblocks
      appear in the dumplfs output with the segment containing them.
- -b
- Use the block specified immediately after the flag as the super block for
      the filesystem.
- -d
- Check partial segment data checksums and report mismatches. This makes
      dumplfsoperate much more slowly.
- -I
- Use the block specified immediately after the flag as the inode block
      containing the index file inode.
- -i
- Dump information about the inode free list.
- -S
- Dump information about the segment table.
- -s
- Add the segment number immediately following the flag to a list of
      segments to dump. This flag may be specified more than once to dump more
      than one segment. The default is to dump all segments.
Thedumplfs command appeared in
  4.4BSD.