fsdb
—
FFS debugging/editing tool
fsdb
opens fsname (usually a raw
disk partition) and runs a command loop allowing manipulation of the file
system's inode data. You are prompted to enter a command with “fsdb
(inum X)>” where X is the currently selected
i-number. The initial selected inode is the root of the filesystem (i-number
2). The command processor uses the
editline(3) library, so you
can use command line editing to reduce typing if desired. When you exit the
command loop, the file system superblock is marked dirty and any buffered
blocks are written to the file system.
The -d
option enables additional debugging
output (which comes primarily from
fsck(8)-derived code).
The -F
option indicates that
filesystem is a file system image, rather than a raw
character device. It will be accessed ‘as-is’, and no attempts
will be made to read a disklabel.
The -n
option disables writing to the
device, preventing any changes from being made to the filesystem.
Besides the built-in editline(3)
commands, fsdb
supports these commands:
help
- Print out the list of accepted commands.
inode
i-number
- Select inode i-number as the new current inode.
back
- Revert to the previously current inode.
clri
i-number
- Clear the inode i-number.
lookup
name
-
cd
name
- Find name in the current directory and make its
inode the current inode. Name may be a
multi-component name or may begin with slash to indicate that the root
inode should be used to start the lookup. If some component along the
pathname is not found, the last valid directory encountered is left as the
active inode.
This command is valid only if the starting inode is a directory.
active
-
print
- Print out the active inode.
uplink
- Increment the active inode's link count.
downlink
- Decrement the active inode's link count.
linkcount
number
- Set the active inode's link count to number.
ls
- List the current inode's directory entries. This command is valid only if
the current inode is a directory.
blks
- List the current inode's blocks numbers.
findblk
disk block number ...
- Find the inode(s) owning the specified disk block(s) number(s). Note that
these are not absolute disk blocks numbers, but offsets from the start of
the partition.
saveblks
filename
- Save the current inode's data into filename.
rm
name
-
del
name
- Remove the entry name from the current directory
inode. This command is valid only if the current inode is a directory.
ln
ino name
- Create a link to inode ino under the name
name in the current directory inode. This command is
valid only if the current inode is a directory.
chinum
dirslot inum
- Change the i-number in directory entry dirslot to
inum.
chname
dirslot name
- Change the name in directory entry dirslot to
name. This command cannot expand a directory entry.
You can only rename an entry if the name will fit into the existing
directory slot.
chtype
type
- Change the type of the current inode to type.
type may be one of: file,
dir, socket, or
fifo.
chmod
mode
- Change the mode bits of the current inode to mode.
You cannot change the file type with this subcommand; use
chtype
to do that.
chflags
flags
- Change the file flags of the current inode to flags.
chown
uid
- Change the owner of the current inode to uid.
chgrp
gid
- Change the group of the current inode to gid.
chgen
gen
- Change the generation number of the current inode to
gen.
mtime
time
-
ctime
time
-
atime
time
- Change the modification, change, or access time (respectively) on the
current inode to time. Time
should be in the format YYYYMMDDHHMMSS[.nsec] where
nsec is an optional nanosecond specification. If no
nanoseconds are specified, the mtimensec,
ctimensec, or atimensec field
will be set to zero.
quit
,
q
, exit
,
⟨EOF⟩
- Exit the program.
fsdb
uses the source code for
fsck(8) to implement most of the
file system manipulation code. The remainder of fsdb
first appeared in NetBSD 1.1.
Use this tool with extreme caution -- you can damage an FFS file system beyond
what fsck(8) can repair.
Manipulation of “short” symlinks doesn't work (in particular,
don't try changing a symlink's type).
You must specify modes as numbers rather than symbolic names.
There are a bunch of other things that you might want to do which
fsdb
doesn't implement.