xref: /freebsd/sbin/dumpfs/dumpfs.8 (revision abd87254)
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28.Dd July 2, 2021
29.Dt DUMPFS 8
30.Os
31.Sh NAME
32.Nm dumpfs
33.Nd dump UFS file system information
34.Sh SYNOPSIS
35.Nm
36.Op Fl f
37.Op Fl l
38.Op Fl m
39.Op Fl s
40.Ar filesys | device
41.Sh DESCRIPTION
42The
43.Nm
44utility prints out the UFS super block and cylinder group information
45for the file system or special device specified, unless the
46.Fl f ,
47.Fl l ,
48.Fl m ,
49or
50.Fl s
51flag is specified.
52The listing is very long and detailed.
53This
54command is useful mostly for finding out certain file system
55information such as the file system block size and minimum
56free space percentage.
57.Pp
58If
59.Fl f
60is specified, a sorted list of all free fragments and free fragment ranges,
61as represented in cylinder group block free lists, is printed.
62If the flag is specified twice, contiguous free fragments are not collapsed
63into ranges and instead printed in a simple list.
64Fragment numbers may be converted to raw byte offsets by multiplying by the
65fragment size, which may be useful when recovering deleted data.
66.Pp
67If
68.Fl l
69is specified, the pathname to the file system's container derived from
70its unique identifier is printed.
71.Pp
72If
73.Fl m
74is specified, a
75.Xr newfs 8
76command is printed that can be used to generate a new file system
77with equivalent settings.
78Please note that
79.Xr newfs 8
80options
81.Fl E ,
82.Fl R ,
83.Fl S ,
84and
85.Fl T
86are not handled and
87.Fl p
88is not useful in this case so is omitted.
89The
90.Xr newfs 8
91options
92.Fl n
93and
94.Fl r
95are neither checked for nor output but should be.
96The
97.Fl r
98flag is needed if the filesystem uses
99.Xr gjournal 8 .
100.Pp
101If
102.Fl s
103is specified, only the super block information is printed.
104.Sh SEE ALSO
105.Xr fs 5 ,
106.Xr fsck 8 ,
107.Xr gpart 8 ,
108.Xr newfs 8 ,
109.Xr tunefs 8
110.Sh HISTORY
111The
112.Nm
113utility appeared in
114.Bx 4.2 .
115