DUMPFS(8)               FreeBSD System Manager's Manual              DUMPFS(8)

NAME
     dumpfs - dump UFS file system information

SYNOPSIS
     dumpfs [-f] [-l] [-m] [-s] filesys | device

DESCRIPTION
     The dumpfs utility prints out the UFS super block and cylinder group
     information for the file system or special device specified, unless the
     -f, -l, -m, or -s flag is 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 and minimum free
     space percentage.

     If -f is specified, a sorted list of all free fragments and free fragment
     ranges, as represented in cylinder group block free lists, is printed.
     If the flag is specified twice, contiguous free fragments are not
     collapsed into ranges and instead printed in a simple list.  Fragment
     numbers may be converted to raw byte offsets by multiplying by the
     fragment size, which may be useful when recovering deleted data.

     If -l is specified, the pathname to the file system's container derived
     from its unique identifier is printed.

     If -m is specified, a newfs(8) command is printed that can be used to
     generate a new file system with equivalent settings.  Please note that
     newfs(8) options -E, -R, -S, and -T are not handled and -p is not useful
     in this case so is omitted.  Newfs(8) options -n and -r are neither
     checked for nor output but should be.  The -r flag is needed if the
     filesystem uses gjournal(8).

     If -s is specified, only the super block information is printed.

SEE ALSO
     fs(5), fsck(8), gpart(8), newfs(8), tunefs(8)

HISTORY
     The dumpfs utility appeared in 4.2BSD.

FreeBSD 13.1-RELEASE-p6          July 2, 2021          FreeBSD 13.1-RELEASE-p6