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FSDB(8) NetBSD System Manager's Manual FSDB(8)
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fsdb -- FFS debugging/editing tool
fsdb [-dFn] -f fsname
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.
Select inode i-number as the new current inode.
back Revert to the previously current inode.
Clear the inode i-number.
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.
print Print out the active inode.
uplink Increment the active inode's link count.
Decrement the active inode's link count.
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.
Save the current inode's data into filename.
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.
Change the type of the current inode to type. type may be one
of: file, dir, socket, or fifo.
Change the mode bits of the current inode to mode. You cannot
change the file type with this subcommand; use chtype to do that.
Change the file flags of the current inode to flags.
Change the owner of the current inode to uid.
Change the group of the current inode to gid.
Change the generation number of the current inode to gen.
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 speci-
fication. If no nanoseconds are specified, the mtimensec,
ctimensec, or atimensec field will be set to zero.
quit, q, exit, <EOF>
Exit the program.
editline(3), fs(5), clri(8), fsck(8)
fsdb uses the source code for fsck(8) to implement most of the file sys-
tem manipulation code. The remainder of fsdb first appeared in
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
NetBSD 9.0 August 3, 2017 NetBSD 9.0