System Administration Commands fsdbufs(1M)
NAME
fsdbufs - ufs file system debugger
SYNOPSIS
fsdb -F ufs [genericoptions] [specificoptions] special
DESCRIPTION
The fsdbufs command is an interactive tool that can be used
to patch up a damaged UFS file system. It has conversions to
translate block and i-numbers into their corresponding disk
addresses. Also included are mnemonic offsets to access dif-
ferent parts of an inode. These greatly simplify the process
of correcting control block entries or descending the file
system tree.
fsdb contains several error-checking routines to verify
inode and block addresses. These can be disabled if neces-
sary by invoking fsdb with the -o option or by the use of
the o command.
fsdb reads a block at a time and will therefore work with
raw as well as block I/O devices. A buffer management rou-
tine is used to retain commonly used blocks of data in order
to reduce the number of read system calls. All assignment
operations result in an immediate write-through of the
corresponding block. Note that in order to modify any por-
tion of the disk, fsdb must be invoked with the w option.
Wherever possible, adb-like syntax was adopted to promote
the use of fsdb through familiarity.
OPTIONS
The following option is supported:
-o Specify UFS file system specific options. These
options can be any combination of the following
separated by commas (with no intervening spaces). The
options available are:
? Display usage
o Override some error conditions
p='string' set prompt to string
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w open for write
USAGE
Numbers are considered hexadecimal by default. However, the
user has control over how data is to be displayed or
accepted. The base command will display or set the
input/output base. Once set, all input will default to this
base and all output will be shown in this base. The base can
be overridden temporarily for input by preceding hexadecimal
numbers with '0x', preceding decimal numbers with '0t', or
octal numbers with '0'. Hexadecimal numbers beginning with
a-f or A-F must be preceded with '0x' to distinguish them
from commands.
Disk addressing by fsdb is at the byte level. However, fsdb
offers many commands to convert a desired inode, directory
entry, block, superblock and so forth to a byte address.
Once the address has been calculated, fsdb will record the
result in dot (.).
Several global values are maintained by fsdb:
o the current base (referred to as base),
o the current address (referred to as dot),
o the current inode (referred to as inode),
o the current count (referred to as count),
o and the current type (referred to as type).
Most commands use the preset value of dot in their execu-
tion. For example,
> 2:inode
will first set the value of dot to 2, ':', will alert the
start of a command, and the inode command will set inode to
2. A count is specified after a ','. Once set, count will
remain at this value until a new command is encountered
which will then reset the value back to 1 (the default). So,
if
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> 2000,400/X
is typed, 400 hex longs are listed from 2000, and when com-
pleted, the value of dot will be 2000 ] 400 * sizeof (long).
If a RETURN is then typed, the output routine will use the
current values of dot, count, and type and display 400 more
hex longs. A '*' will cause the entire block to be
displayed.
End of fragment, block and file are maintained by fsdb. When
displaying data as fragments or blocks, an error message
will be displayed when the end of fragment or block is
reached. When displaying data using the db, ib, directory,
or file commands an error message is displayed if the end of
file is reached. This is mainly needed to avoid passing the
end of a directory or file and getting unknown and unwanted
results.
An example showing several commands and the use of RETURN
would be:
> 2:ino; 0:dir?d
or
> 2:ino; 0:db:block?d
The two examples are synonymous for getting to the first
directory entry of the root of the file system. Once there,
any subsequent RETURN (or ], -) will advance to subsequent
entries. Note that
> 2:inode; :ls
or
> :ls /
is again synonymous.
Expressions
The symbols recognized by fsdb are:
RETURN update the value of dot by the current value of
type and display using the current value of
count.
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# numeric expressions may be composed of ], -, *,
and % operators (evaluated left to right) and
may use parentheses. Once evaluated, the value
of dot is updated.
, count count indicator. The global value of count will
be updated to count. The value of count will
remain until a new command is run. A count
specifier of '*' will attempt to show a
blocks's worth of information. The default for
count is 1.
? f display in structured style with format specif-
ier f. See FormattedOutput.
/ f display in unstructured style with format
specifier f See FormattedOutput.
. the value of dot.
]e increment the value of dot by the expression e.
The amount actually incremented is dependent on
the size of type:
dot = dot ] e * sizeof (type)
The default for e is 1.
-e decrement the value of dot by the expression e.
See ].
*e multiply the value of dot by the expression e.
Multiplication and division don't use type. In
the above calculation of dot, consider the
sizeof(type) to be 1.
%e divide the value of dot by the expression e.
See *.
< name restore an address saved in register name. name
must be a single letter or digit.
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> name save an address in register name. name must be
a single letter or digit.
= f display indicator. If f is a legitimate format
specifier. then the value of dot is displayed
using the format specifier f. See FormattedOut-
put. Otherwise, assignment is assumed See =.
= [s] [e] assignment indicator. The address pointed to by
dot has its contents changed to the value of
the expression e or to the ASCI representation
of the quoted (") string s. This may be useful
for changing directory names or ASCI file
information.
=] e incremental assignment. The address pointed to
by dot has its contents incremented by expres-
sion e.
=- e decremental assignment. The address pointed to
by dot has its contents decremented by expres-
sion e.
Commands
A command must be prefixed by a ':' character. Only enough
letters of the command to uniquely distinguish it are
needed. Multiple commands may be entered on one line by
separating them by a SPACE, TAB or ';'.
In order to view a potentially unmounted disk in a reason-
able manner, fsdb offers the cd, pwd, ls and find commands.
The functionality of these commands substantially matches
those of its UNIX counterparts. See individual commands for
details. The '*', '?', and '[-]' wild card characters are
available.
base=b
display or set base. As stated above, all input and out-
put is governed by the current base. If the =b is omit-
ted, the current base is displayed. Otherwise, the
current base is set to b. Note that this is interpreted
using the old value of base, so to ensure correctness
use the '0', '0t', or '0x' prefix when changing the
base. The default for base is hexadecimal.
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block
convert the value of dot to a block address.
cd dir
change the current directory to directory dir. The
current values of inode and dot are also updated. If no
dir is specified, then change directories to inode 2
("/").
cg
convert the value of dot to a cylinder group.
directory
If the current inode is a directory, then the value of
dot is converted to a directory slot offset in that
directory and dot now points to this entry.
file
the value of dot is taken as a relative block count from
the beginning of the file. The value of dot is updated
to the first byte of this block.
find dir [ -name n] [-inum i]
find files by name or i-number. find recursively
searches directory dir and below for filenames whose i-
number matches i or whose name matches pattern n. Note
that only one of the two options (-name or -inum) may be
used at one time. Also, the -print is not needed or
accepted.
fill=p
fill an area of disk with pattern p. The area of disk is
delimited by dot and count.
fragment
convert the value of dot to a fragment address. The only
difference between the fragment command and the block
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command is the amount that is able to be displayed.
inode
convert the value of dot to an inode address. If suc-
cessful, the current value of inode will be updated as
well as the value of dot. As a convenient shorthand, if
':inode' appears at the beginning of the line, the value
of dot is set to the current inode and that inode is
displayed in inode format.
logchk
run through the valid log entries without printing any
information and verify the layout.
logdelta
count the number of deltas into the log, using the value
of dot as an offset into the log. No checking is done to
make sure that offset is within the head/tail offsets.
loghead
display the header information about the file system
logging. This shows the block allocation for the log and
the data structures on the disk.
logotodb
return the physical disk block number, using the value
of dot as an offset into the log.
logshow
display all deltas between the beginning of the log
(BOL) and the end of the log (EOL).
ls
[ -R ] [ -l ] pat1 pat2... list directories or files. If
no file is specified, the current directory is assumed.
Either or both of the options may be used (but, if used,
must be specified before the filename specifiers). Also,
as stated above, wild card characters are available and
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multiple arguments may be given. The long listing shows
only the i-number and the name; use the inode command
with '?i' to get more information.
override
toggle the value of override. Some error conditions may
be overriden if override is toggled on.
prompt p
change the fsdb prompt to p. p must be surrounded by
(")s.
pwd
display the current working directory.
quit
quit fsdb.
sb
the value of dot is taken as a cylinder group number and
then converted to the address of the superblock in that
cylinder group. As a shorthand, ':sb' at the beginning
of a line will set the value of dot to the superblock
and display it in superblock format.
shadow
if the current inode is a shadow inode, then the value
of dot is set to the beginning of the shadow inode data.
!
escape to shell
Inode Commands
In addition to the above commands, there are several com-
mands that deal with inode fields and operate directly on
the current inode (they still require the ':'). They may be
used to more easily display or change the particular fields.
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The value of dot is only used by the ':db' and ':ib' com-
mands. Upon completion of the command, the value of dot is
changed to point to that particular field. For example,
> :ln=]1
would increment the link count of the current inode and set
the value of dot to the address of the link count field.
at access time.
bs block size.
ct creation time.
db use the current value of dot as a direct block index,
where direct blocks number from 0 - 11. In order to
display the block itself, you need to 'pipe' this
result into the block or fragment command. For exam-
ple,
> 1:db:block,20/X
would get the contents of data block field 1 from the
inode and convert it to a block address. 20 longs are
then displayed in hexadecimal. See FormattedOutput.
gid group id.
ib use the current value of dot as an indirect block
index where indirect blocks number from 0 - 2. This
will only get the indirect block itself (the block
containing the pointers to the actual blocks). Use
the file command and start at block 12 to get to the
actual blocks.
ln link count.
mt modification time.
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md mode.
maj major device number.
min minor device number.
nm although listed here, this command actually operates
on the directory name field. Once poised at the
desired directory entry (using the directory com-
mand), this command will allow you to change or
display the directory name. For example,
> 7:dir:nm="foo"
will get the 7th directory entry of the current inode
and change its name to foo. Note that names cannot be
made larger than the field is set up for. If an
attempt is made, the string is truncated to fit and a
warning message to this effect is displayed.
si shadow inode.
sz file size.
uid user id.
Formatted Output
There are two styles and many format types. The two styles
are structured and unstructured. Structured output is used
to display inodes, directories, superblocks and the like.
Unstructured displays raw data. The following shows the dif-
ferent ways of displaying:
?
c display as cylinder groups
i display as inodes
d display as directories
s display as superblocks
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S display as shadow inode data
/
b display as bytes
c display as characters
o O display as octal shorts or longs
d D display as decimal shorts or longs
x X display as hexadecimal shorts or longs
The format specifier immediately follows the '/' or '?'
character. The values displayed by '/b' and all '?'
formats are displayed in the current base. Also, type
is appropriately updated upon completion.
EXAMPLES
Example 1 Displaying in Decimal
The following command displays 2010 in decimal (use of fsdb
as a calculator for complex arithmetic):
> 2000]400%(20]20)=D
Example 2 Displaying an i-number in Inode Format
The following command displays i-number 386 in an inode for-
mat. This now becomes the current inode:
> 386:ino?i
Example 3 Changing the Link Count
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The following command changes the link count for the current
inode to 4:
> :ln=4
Example 4 Incrementing the Link Count
The following command increments the link count by 1:
> :ln=]1
Example 5 Displaying the Creation Time
The following command displays the creation time as a hexa-
decimal long:
> :ct=X
Example 6 Displaying the Modification Time
The following command displays the modification time in time
format:
> :mt=t
Example 7 Displaying in ASCI
The following command displays in ASCI, block zero of the
file associated with the current inode:
> 0:file/c
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Example 8 Displaying the First Block's Worth of Directorty
Entries
The following command displays the first block's worth of
directory entries for the root inode of this file system. It
will stop prematurely if the EOF is reached:
> 2:ino,*?d
Example 9 Displaying Changes to the Current Inode
The following command displays changes the current inode to
that associated with the 5th directory entry (numbered from
zero) of the current inode. The first logical block of the
file is then displayed in ASCI:
> 5:dir:inode; 0:file,*/c
Example 10 Displaying the Superblock
The following command displays the superblock of this file
system:
> :sb
Example 11 Displaying the Cylinder Group
The following command displays cylinder group information
and summary for cylinder group 1:
> 1:cg?c
Example 12 Changing the i-number
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The following command changes the i-number for the seventh
directory slot in the root directory to 3:
> 2:inode; 7:dir=3
Example 13 Displaying as Directory Entries
The following command displays the third block of the
current inode as directory entries:
> 2:db:block,*?d
Example 14 Changing the Name Field
The following command changes the name field in the direc-
tory slot to name:
> 7:dir:nm="name"
Example 15 Getting and Filling Elements
The following command gets fragment 3c3 and fill 20 type
elements with 0x20:
> 3c3:fragment,20:fill=0x20
Example 16 Setting the Contents of an Address
The following command sets the contents of address 2050 to
0xffffffff. 0xffffffff may be truncated depending on the
current type:
> 2050=0xffff
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Example 17 Placing ASCI
The following command places the ASCI for the string at
1c92434:
> 1c92434="this is some text"
Example 18 Displaying Shadow Inode Data
The following command displays all of the shadow inode data
in the shadow inode associated with the root inode of this
file system:
> 2:ino:si:ino;0:shadow,*?S
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWcsu
SEE ALSO
clri(1M), fsckufs(1M), dirufs(4), attributes(5), ufs(7FS)
WARNINGS
Since fsdb reads the disk raw, extreme caution is advised in
determining its availability of fsdb on the system. Sug-
gested permissions are 600 and owned by bin.
NOTES
The old command line syntax for clearing i-nodes using the
ufs-specific '-z i-number' option is still supported by the
new debugger, though it is obsolete and will be removed in a
future release. Use of this flag will result in correct
operation, but an error message will be printed warning of
the impending obsolesence of this option to the command. The
equivalent functionality is available using the more
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flexible clri(1M) command.
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