fsdb(1M) (s5) fsdb(1M)
NAME
fsdb (s5) - s5 file system debugger
SYNOPSIS
fsdb [-F s5] [generic_options] [-z i-number] special [-]
DESCRIPTION
generic_options are options supported by the generic fsdb command.
fsdb can be used to patch up a damaged s5 file system after a crash.
It has conversions to translate block and i-numbers into their
corresponding disk addresses. Also included are mnemonic offsets to
access different parts of an i-node. These greatly simplify the
process of correcting control block entries or descending the file
system tree.
fsdb contains several error-checking routines to verify i-node and
block addresses. These can be disabled if necessary by invoking fsdb
with the optional - argument or by the use of the O symbol. (fsdb
reads the i-size and f-size entries from the superblock of the file
system as the basis for these checks.)
The options are:
-F s5 Specifies the s5-FSType.
-z i-number Clear the i-node identified by i-number. Non-
interactive.
Numbers are considered decimal by default. Octal numbers must be
prefixed with a zero. During any assignment operation, numbers are
checked for a possible truncation error due to a size mismatch
between source and destination.
fsdb reads a block at a time and will therefore work with raw as well
as block I/O. A buffer management routine 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.
The symbols recognized by fsdb are:
# absolute address
i convert from i-number to i-node address
b convert to block address
d directory slot offset
+ , - address arithmetic
q quit
> , < save, restore an address
= numerical assignment
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fsdb(1M) (s5) fsdb(1M)
=+ incremental assignment
=- decremental assignment
=" character string assignment
O error checking flip flop
p general print facilities
f file print facility
B byte mode
W word mode
D double word mode
! escape to shell
The print facilities generate a formatted output in various styles.
The current address is normalized to an appropriate boundary before
printing begins. It advances with the printing and is left at the
address of the last item printed. The output can be terminated at
any time by typing the delete character. If a number follows the p
symbol, that many entries are printed. A check is made to detect
block boundary overflows since logically sequential blocks are
generally not physically sequential. If a count of zero is used, all
entries to the end of the current block are printed. The print
options available are:
i print as i-nodes
d print as directories
o print as octal words
e print as decimal words
c print as characters
b print as octal bytes
The f symbol is used to print data blocks associated with the
current i-node. If followed by a number, that block of the file is
printed. (Blocks are numbered from zero.) The desired print option
letter follows the block number, if present, or the f symbol. This
print facility works for small as well as large files. It checks for
special devices and that the block pointers used to find the data are
not zero.
Dots, tabs, and spaces may be used as function delimiters but are not
necessary. A line with just a new-line character will increment the
current address by the size of the data type last printed. That is,
the address is set to the next byte, word, double word, directory
entry or i-node, allowing the user to step through a region of a file
system. Information is printed in a format appropriate to the data
type. Bytes, words and double words are displayed with the octal
address followed by the value in octal and decimal. A .B or .D is
appended to the address for byte and double word values,
respectively. Directories are printed as a directory slot offset
followed by the decimal i-number and the character representation of
the entry name. I-nodes are printed with labeled fields describing
each element.
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fsdb(1M) (s5) fsdb(1M)
The following mnemonics are used for i-node examination and refer to
the current working i-node:
md mode
ln link count
uid user ID number
gid group ID number
sz file size
a # data block numbers (0 - 12)
at access time
mt modification time
maj major device number
min minor device number
EXAMPLES
386i prints i-number 386 in an i-node format. This now
becomes the current working i-node.
ln=4 changes the link count for the working i-node to 4.
ln=+1 increments the link count by 1.
fc prints, in ASCII, block zero of the file associated
with the working i-node.
2i.fd prints the first 32 directory entries for the root
i-node of this file system.
d5i.fc changes the current i-node to that associated with
the 5th directory entry (numbered from zero) found
from the above command. The first logical block of
the file is then printed in ASCII.
512B.p0o prints the superblock of this file system in octal.
2i.a0b.d7=3 changes the i-number 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="name" changes the name field in the directory slot to the
given string. Quotes are optional when used with nm
if the first character is alphabetic.
a2b.p0d prints the third block of the current i-node as
directory entries.
SEE ALSO
fsck(1M), generic fsdb(1M).
dir(4), fs(4) in the Programmers Reference Manual
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