fsdb(1M) UNIX System V(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.
special is a special device used to indicate the file system to be
debugged. 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
=+ incremental assignment
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fsdb(1M) UNIX System V(s5) fsdb(1M)
=- 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.
The following mnemonics are used for i-node examination and refer to the
current working i-node:
md mode
ln link count
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fsdb(1M) UNIX System V(s5) fsdb(1M)
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).
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