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
file system (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 options are as follows:
- Enables additional debugging output (which comes primarily from
- Open file system fsname.
Besides the built-in
fsdb supports these commands:
- Print out the list of accepted commands.
- Select inode i-number as the new current inode.
- 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
This command is valid only if the starting inode is a
- Print out the active inode.
- Increment the active inode's link count.
- Decrement the active inode's link count.
- Set the active inode's link count to number.
- List the current inode's directory entries. This command is valid only if
the current inode is a directory.
- Remove the entry name from the current directory
inode. This command is valid only if the current inode is a directory.
- 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.
- Change the i-number in directory entry dirslot to
- 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
- Change the type of the current inode to type.
type may be one of: file,
dir, socket, or
- 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 length of the current inode to length.
- Change the group of the current inode to gid.
- Change the generation number of the current inode to
- 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.
- Exit the program.
fsdb uses the source code for
fsck(8) to implement most of the
file system manipulation code. The remainder of
first appeared in NetBSD 1.1.
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
Use this tool with extreme caution – you can damage an FFS file system
beyond what fsck(8) can repair.
fsdb doesn't implement.