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NAME [Toc] [Back]
fsdb_vxfs: fsdb - VxFS file system debugger
SYNOPSIS [Toc] [Back]
fsdb [-F vxfs] [-z inumber] special
DESCRIPTION [Toc] [Back]
fsdb can analyze VxFS file system problems or repair a damaged VxFS
file system after a crash. A special device special specifies the
file system to debug. The fsdb command is intended for experienced
users only.
fsdb can convert block and inumbers into their corresponding disk
addresses. In addition, mnemonic offsets allow access to different
parts of an inode. These greatly simplify the process of correcting
control block entries or descending the file system tree.
By default, numbers are considered decimal. You must prefix octal
numbers with 0, and prefix hexadecimal numbers with 0x. When using
hexadecimal numbers, it is preferable to follow the number with a
space, because several commands are letters that are also hexadecimal
digits. In this document a pound sign (#) indicates that a number is
to be specified.
fsdb reads a block at a time and works with raw and block I/O. All
I/O is unbuffered, so changes made to the file system are immediate
and changes made by other processes or by the kernel are immediately
seen by fsdb.
Options [Toc] [Back]
fsdb recognizes the following options:
generic_options
Supported by the generic fsdb command. See
fsdb(1M).
-F vxfs Specify the VxFS file-system type.
-z inumber Clear the inode identified by inumber (noninteractive).
Multiple -z options accumulate.
Operands [Toc] [Back]
fsdb recognizes the following operand:
special Name of the special device that contains the VxFS
file system to debug.
Using Commands and Symbols [Toc] [Back]
It is best to separate each token on a command line with a space.
Although the command parser does not require element separation, there
is no ambiguity in the command language if each token is separated
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with a space. For example, the command 0x23b b sets the current
position to block 0x23b hexadecimal. The command 0x23bb is invalid,
because the command is parsed as simply a hexadecimal number. The
command 23b positions to block 23 decimal, since the command is not
ambiguous.
You can separate commands with new lines. You can put multiple
commands on one line and separate them with a dot (.) or a semicolon
(;) If multiple commands are placed on one line, generally only the
last command displays results. This allows positioning commands to be
followed by printing commands or change commands without intermediate
printing.
Symbols for the fsdb Command [Toc] [Back]
The following symbols are recognized by the fsdb command:
h[mod|print] Print summary of commands that display
[modify|format] the file system.
?[mod|print] Print summary of commands that display
[modify|format] the file system.
help[mod|print]
Print summary of commands that display
[modify|format] the file system.
! Escape to shell.
| Pipe output of fsdb to a shell command.
q Quit.
string A character string. Inside a character string, a
NULL character can be specified with ``\0''; a
double quote can be specified with ``\"''; and a
backslash can be specified with ``\\ ''.
+ - * / % Add, subtract, multiply, divide, and modulus.
= Assignment
i An inode in the primary inode list.
ai An inode in the attribute inode list.
au An allocation unit.
b A block.
im The immediate data area of an inode. Small
directories and symbolic link files (96 bytes or
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less) are stored directly in the inode itself, in
the area normally occupied by data block numbers
and extent sizes.
attr An attribute inode.
cdb Current directory block.
d A directory entry.
a An inode address entry.
B A byte.
H A half-word (2 bytes)
W A word (4 bytes)
D A double-word (8 bytes)
p General print facility
calc Simple calculator and base converter
find Find a matching pattern in the file system
fset A fileset.
iau An inode allocation unit in the primary inode
list.
aiau An inode allocation unit in the attribute inode
list.
cut The current usage table.
olt The object location table.
mapi Map logical file offset to an inode extent.
reset Reset device.
Print Facility Print Formats [Toc] [Back]
The print facility recognizes the following print formats:
S Print as a super-block.
A Print as an allocation-unit header.
AS Print as an auxiliary super-block.
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L Print as intent-log records.
I Print as inodes.
ST List state table blocks.
T Print as typed extent descriptors.
dent Print as directory entries.
db Print as a directory block.
dh Print as a directory header.
o Print as octal words.
oB oH oW oD Print as octal bytes, half-words, words, or
double-words.
x Print as hexadecimal words.
xB xH xW xD Print as hexadecimal bytes, half-words, words, or
double-words.
e Print as decimal words.
eB eH eW eD Print as decimal bytes, half-words, words, or
double-words.
u Print as unsigned words.
uB uH uW uD Print as unsigned bytes, half-words, words, or
double-words.
c Print as characters.
F Print as fileset headers.
C Print as current usage table entries.
IA Print as an inode allocation unit header.
oltext Print as an object location table extent.
Q Prints as a BSD quota record.
DV Print as a device record.
Symbols in Inode Fields [Toc] [Back]
Changes to inode fields can be made symbolically. The following
symbols represent inode fields:
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md Inode mode field
ln Inode link count field
uid Inode user ID Number field
gid Inode group ID Number field
szlo Low-order word of inode file size field
szhi High-order word of inode file size field
sz Inode file size field
de# Inode direct extent data block numbers (0 - 9)
des# Inode direct extent sizes (0 - 9)
ie# Inode indirect extent data block numbers (0 - 1)
ies Inode indirect extent size
at Inode access time field (seconds)
ats Inode access time field (microseconds).
ct Inode change time field (seconds).
cts Inode change time field (microseconds).
mt Inode modification time field (seconds).
mts Inode modification time field (microseconds).
af Inode allocation flags field.
gen Inode generation count field.
org Inode mapping type field.
fe Inode fixed extent size field.
bl Inode blocks held field.
eopflg Inode extended operation flag field.
eopdat Inode extended operation data field.
rdev If device, inode device number.
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maj If device, inode major number.
min If device, inode minor number.
pd If directory, inode parent directory.
res If regular file, inode reservation.
verhi Inode high-order word of serial number.
verlo Inode low-order word of serial number.
fsindex Referencing fileset ID.
matching Inode number of matching inode.
iano Indirect attribute inode.
Symbols for Directory Block Fields [Toc] [Back]
Changes to directory block fields can be made symbolically. The
following symbols represent directory block fields:
tfree Total free space (only if in a data block).
hash# Hash chain start (0 through 31, only if in a data
block).
d# Directory entry (variable number of entries).
nhash Number of hash chains.
Symbols for Directory Entry Fields [Toc] [Back]
Changes to directory entry fields can be made symbolically. The
following symbols represent directory entry fields:
ino Inode number
nm Entry name
nmlen Name length
reclen Record length (only if in a data block)
hnext Name hash next (only if in a data block)
Positions in File Systems and Positioning Commands [Toc] [Back]
fsdb maintains several positions in the file system:
+ current position
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+ current primary-inode position (i)
+ current attribute-inode position (ai)
+ current inode type (i or ai)
+ current fileset-header position (fset)
+ current allocation-unit position (au)
+ current primary-inode allocation-unit (iau) position
+ current inode allocation-unit type (iau or aiau)
+ current attribute-inode allocation-unit (aiau) position
These are used by various fsdb commands. (The au positions are only
supported on the Version 2 disk layout.)
The following commands are supported:
# B|H|W|D Set the current position in the file system to the
specified offset in bytes, half-words, words, or
double-words. If it is the last command on a
line, print the byte, half-word, word, or doublewords
in hexadecimal.
+|- # B|H|W|D Set the current position to the specified relative
offset in bytes, half-words, words, or doublewords.
If it is the last command on a line, print
the byte, half-word, word, or double-words in
hexadecimal.
# au Set the current position in the file system to the
specified allocation unit (au) position. Set the
current allocation unit position to the resulting
offset. If it is the last command on a line,
print the allocation unit header.
+|- # au Set the current position in the file system to the
specified position relative to the current
allocation unit (au) position. Set the current
allocation unit position to the resulting offset.
If it is the last command on a line, print the
allocation unit header.
au Set the current position in the file system to the
current allocation unit position. If it is the
last command on a line, print the allocation unit
header.
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# b Set the current position in the file system to the
specified offset in blocks. Set the current block
position to the resulting offset. The block size
is the block size of the file system. If it is
the last command on a line, print the first word
in the block in hexadecimal.
+|- # b Set the current position to specified relative
offset in blocks. Set the current block position
to the resulting offset. If it is the last
command on a line, print the first word in the
block in hexadecimal.
b Set the current position to current block position
(the block specified by the last [+|-] # b
operation). If it is the last command on a line,
print the first word in the block in hexadecimal.
cut Set the current position to the current usage
table (cut). If it is the last command on a line,
print the first current usage table entry.
dev Set the current position to the primary device's
configuration record. If it is the last command
on a line, print the device-configuration record.
# fset Set the current position in the file system to the
fileset header entry for the specified fileset
index. Set the current fileset position to the
resulting offset. If it is the last command on a
line, print the specified fileset header.
+|- # fset Set the current position in the file system to the
fileset header entry for the specified position
relative to the current fileset position. Set the
current fileset position to resulting offset. If
it is the last command on a line, print the
specified fileset header.
fset Set the current position in the file system to the
current fileset position. If it is the last
command on a line, print the fileset header for
the current fileset.
# aiau Set the current position in the file system to the
specified attribute inode allocation unit (aiau)
in a fileset. Set the current attribute inode
allocation unit position to the resulting offset.
If it is the last command on a line, print the
attribute inode allocation unit header.
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+|- # aiau Set the current position in the file system to the
specified position relative to the current
attribute inode allocation unit (aiau) position.
Set the current attribute inode allocation unit
position to the resulting offset. If it is the
last command on a line, print the attribute inode
allocation unit header.
aiau Set the current position in the file system to the
current attribute inode allocation unit (aiau)
position. If it is the last command on a line,
print the attribute inode allocation unit header.
# iau Set the current position in the file system to the
specified inode allocation unit (iau) in a
fileset. Set the current inode allocation unit
position to the resulting offset. If it is the
last command on a line, print the inode allocation
unit header.
+|- # iau Set the current position in the file system to the
specified position relative to the current inode
allocation unit (iau) position. Set the current
inode allocation unit position to the resulting
offset. If it is the last command on a line,
print the inode allocation unit header.
iau Set the current position in the file system to the
current inode allocation unit (iau) position. If
it is the last command on a line, print the inode
allocation unit header.
# ai Set the current position in the current fileset to
the ilist entry for the specified attribute inode.
Set the current attribute inode position to the
resulting offset. If it is the last command on a
line, print the ilist entry for the inode.
+|- # ai Set the current position in the current fileset to
the ilist entry for the specified relative
attribute inode. Set the current attribute inode
position to the resulting offset. If it is the
last command on a line, print the ilist entry for
the inode.
ai Set the current position in the current fileset to
the current attribute inode position. If it is
the last command on a line, print the ilist entry
for the inode.
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# i Set the current position in the current fileset to
the ilist entry for the specified inode. Set the
current inode position to the resulting offset.
If it is the last command on a line, print the
ilist entry for the inode.
+|- # i Set the current position in the current fileset to
the ilist entry for the specified relative inode.
Set the current inode position to the resulting
offset. If it is the last command on a line,
print the ilist entry for the inode.
i Set the current position in the current fileset to
the current inode position. If it is the last
command on a line, print the ilist entry for the
inode.
a# Set the current position to specified offset in
blocks specified by the inode address #.
Addresses 0 through 9 are for direct extents ( de
). Addresses 10-11 are for indirect extents ( ie
). The addresses are displayed when printing an
ilist entry. Set the current block position to
the resulting offset. If it is the last command
on a line, print the first word in the block in
hexadecimal.
im Set the current position to immediate data area of
the current inode. Set the current block position
to the resulting offset. If it is the last
command on a line, print the first word of the
area in hexadecimal.
attr Set the current position to attribute data area of
the current inode. Set the current block position
to the resulting offset. If it is the last
command on a line, print the first word in the
block in hexadecimal.
# B|H|W|D =# [#]
Set the current position and change the number at
the specified offset to the given number. If a
double-word offset is specified, then two numbers
separated by a space are required. The resulting
value is printed in hexadecimal.
+|-# B|H|W|D =# [#]
Set the current position and change the number at
the specified relative offset to the given number.
If a double-word offset is specified, then two
numbers separated by a space are required. The
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resulting value is printed in hexadecimal.
# B|H|W|D = string
Set the current position and change the characters
at the specified offset to the given string. The
resulting value is printed as a character string.
+|- # B|H|W|D = string
Set the current position and change the characters
at the specified relative offset to the given
string. The resulting value is printed as a
character string.
olt Set the current position to the object location
table (olt). If it is the last command on a line,
print the object location table.
p [#] format Print the contents of the file system at the
current offset as the specified number of entries
of a given format. The allowable print formats
are specified above. If a number of entries to
print is not specified, one entry is printed.
inode_field = #
Set the contents of the given inode field to the
specified number. The current inode specifies the
inode list entry to be modified. The symbols
representing inode fields are listed above.
directory_block_field = #
Set the contents of the given directory block
field to the specified number. The current block
is treated as a directory block and the offset in
that block which is represented by the given field
is changed. The symbols representing directory
block fields are listed above.
d# Set the current directory entry to the specified
number. The current block is treated as a
directory block. If the current block is an
immediate data area for an inode, then the block
is treated as containing immediate directory
entries. If it is the last command on a line, the
directory entry at the resulting offset is
printed.
directory_entry_field = #
Set the contents of the given directory field to
the specified number. The current directory entry
specifies where the directory entry is located.
The resulting value is printed in hexadecimal.
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nm = string Set the directory name field of the current
directory entry to the specified string. The
resulting value is printed as a character string.
calc # [+|-|*|/ #]
Take a number or the sum, difference, product or
dividend of two numbers and print in decimal,
octal, hexadecimal and character format.
find # B|H|W|D [#]
Search for the given numeric pattern in the file
system. The size of the object to match is
specified. If a double-word is specified, then
two numbers must be given. The search is
performed forward from the current offset. A
maximum number of blocks to search can be
specified. If found, the location and value are
printed in hexadecimal.
find string [#]
Search for the given character string in the file
system. The search is performed forward from the
current offset. A maximum number of blocks to
search can be specified. If found the location
and string are printed.
fmtlog Format all intent log entries. A completely
formatted intent log can be quite lengthy. It is a
good idea use the fsdb command as a filter and
redirect the output to a file or pager to look at
a complete log format.
listfset List all filesets by their indexes and names.
mapi # Treat the number as a logical offset in the file
described by the current inode, and print the
extent that it maps to.
reset Does the equivalent of exiting fsdb and restarting
on same device.
Help Commands [Toc] [Back]
The following help commands are supported:
h|help Display primary help screen.
h mod Display modification-commands help screen.
h print Display print-commands help screen.
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EXAMPLES [Toc] [Back]
386i Prints inumber 386 in an inode format. This now
becomes the current working inode.
ln=4 Changes the link count for the working inode to 4.
8192B.p S Prints the super-block of this file system
symbolically.
d7.nm = foo Changes the name field in the directory slot to foo.
2i.a0.d7.ino = 3
Changes the inumber for the seventh directory slot in
the root directory to three (also shows how to combine
several operations on one command line)
23i.im.d5 Prints the sixth directory entry in the immediate area
of inode 23.
WARNINGS [Toc] [Back]
Always run a file system check (see fsck(1M)) after using the fsdb
command to modify a file system. (Use fsck -o full,nolog.)
Some aspects of fsdb apply to a specific VxFS disk layout version.
SEE ALSO [Toc] [Back]
fsck_vxfs(1M), fsdb(1M).
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