FSDB(8)

NAME
fsdb - FFS debugging/editing tool

SYNOPSIS
fsdb [-dFn] -f fsname

DESCRIPTION
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.

COMMANDS
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
    Clear the current inode.

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.

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.

SEE ALSO
editline(3), fs(5), clri(8), fsck(8)

HISTORY
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.

WARNING
Use this tool with extreme caution -- you can damage an FFS file system beyond what fsck(8) can repair.

BUGS
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.