fsdb_vxfs(ADM)

Synopsis

Description

The fsdb command has conversions to translate block and inumbers into their corresponding disk addresses. Also included are mnemonic offsets to access 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. Octal numbers must be prefixed with 0. Hexadecimal numbers must be prefixed with 0x. When using hexadecimal numbers, it is preferable to follow the number with a space, since a number of commands are letters that are also hexadecimal digits. In this document a pound sign (#) is used to indicate that a number is to be specified.

The fsdb command 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 the fsdb command.

Options

generic_options

Supported by the generic fsdb command (see fsdb(ADM)).

-F vxfs

Specify the vxfs file system type. If -F vxfs is not specified heuristics similiar to those used by fstyp(ADM) are used to determine the file system type.

---

This command executes faster if it is not required to autodetect file system types. If possible, specify -F vxfs

---

-z inumber

Clear the inode identified by inumber (non-interactive). Multiple -z options accumulate.

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 command to a shell command.

q

Quit.

"string"

A character string. Inside a character string, a NULL character may be specified with ''\0''; a double quote may be specified with ''\"''; and a backslash may 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 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.

S

Print as a super-block.

A

Print as an allocation-unit header.

AS

Print as an auxiliary super-block.

L

Print as intent-log records.

I

Print as inodes.

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.

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

Print as a BSD quota record.

DV

Print as a device record.

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.

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.

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.

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)

Commands are separated by new lines, or multiple commands may be placed on one line, separated by a period (.) or a semicolon (;). When 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.

The fsdb command maintains several positions in the file system:

• current position
• 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

The following commands are supported:

# B|H|W|D

Set current position in the file system to the specified offset in bytes, half-words, words, or double-words. If the last command on a line, print the byte, half-word, word, or double-words in hexadecimal.

+|- # B|H|W|D

Set current position to specified relative offset in bytes, half-words, words, or double- words. If the last command on a line, print the byte, half-word, word, or double- words in hexadecimal.

# au

Set current position in the file system to the specified allocation unit (au) position. Set current allocation unit position to the resulting offset. If the last command on a line, print the allocation unit header.

+|- # au

Set current position in the file system to the specified position relative to the current allocation unit (au) position. Set current allocation unit position to the resulting offset. If the last command on a line, print the allocation unit header.

au

Set current position in the file system to the current allocation unit position. If the last command on a line, print the allocation unit header.

# b

Set current position in the file system to the specified offset in blocks. Set current block position to the resulting offset. The block size is the block size of the file system. If the last command on a line, print the first word in the block in hexadecimal.

+|- # b

Set current position to specified relative offset in blocks. Set current block position to the resulting offset. If the last command on a line, print the first word in the block in hexadecimal.

b

Set current position to current block position (the block specified by the last [+|-] # b operation). If the last command on a line, print the first word in the block in hexadecimal.

cut

Set current position to the current usage table (cut). If the last command on a line, print the first current usage table entry.

dev

Set current position to the primary device's configuration record. If the last command on a line, print the device-configuration record.

# fset

Set current position in the file system to the fileset header entry for the specified fileset index. Set current fileset position to the resulting offset. If the last command on a line, print the specified fileset header.

+|- # fset

Set current position in the file system to the fileset header entry for the specified position relative to the current fileset position. Set current fileset position to resulting offset. If the last command on a line, print the specified fileset header.

fset

Set current position in the file system to the current fileset position. If the last command on a line, print the fileset header for the current fileset.

# aiau

Set 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 the last command on a line, print the attribute inode allocation unit header.

+|- # 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 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 the last command on a line, print the attribute inode allocation unit header.

# iau

Set 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 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 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 the last command on a line, print the inode allocation unit header.

# ai

Set current position in the current fileset to the ilist entry for the specified attribute inode. Set current attribute inode position to the resulting offset. If the last command on a line, print the ilist entry for the inode.

+|- # ai

Set current position in the current fileset to the ilist entry for the specified relative attribute inode. Set current attribute inode position to the resulting offset. If the last command on a line, print the ilist entry for the inode.

ai

Set current position in the current fileset to the current attribute inode position. If the last command on a line, print the ilist entry for the inode.

# i

Set current position in the current fileset to the ilist entry for the specified inode. Set current inode position to the resulting offset. If the last command on a line, print the ilist entry for the inode.

+|- # i

Set current position in the current fileset to the ilist entry for the specified relative inode. Set current inode position to the resulting offset. If the last command on a line, print the ilist entry for the inode.

i

Set current position in the current fileset to the current inode position. If the last command on a line, print the ilist entry for the inode.

a#

Set 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 current block position to the resulting offset. If the last command on a line, print the first word in the block in hexadecimal.

im

Set current position to immediate data area of the current inode. Set current block position to the resulting offset. If the last command on a line, print the first word of the area in hexadecimal.

attr

Set current position to attribute data area of the current inode. Set current block position to the resulting offset. If 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 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 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 previously listed.

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 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.

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 may 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 may 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.

h|help

Display primary help screen.

h mod

Display modification-commands help screen.

h print

Display print-commands help screen.

Examples

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.

1024B.p S

Prints the super-block of this file system symbolically.

2i.a0b.d7.ino = 3

Changes the inumber for the seventh directory slot in the root directory to 3. This example also shows how several operations can be combined on one command line.

d7.nm = "foo "

Changes the name field in the directory slot to "foo".

23i.im.pdb

Prints the immediate area of inode 23 as a directory block.

23i.im.d5

Prints the sixth directory entry in the immediate area of inode 23.

Warnings

Always execute fsck after using the fsdb command to modify a file system (use fsck -o full, nolog).

Some aspects of fsdb apply to a specific version of vxfs disk layout.

References

fsck(ADM), fsdb(ADM), fstyp(ADM)