---
name: "fsdb"
section: "8"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["freebsd", "openbsd"]
url: "https://new.carta.tech/fsdb"
---

# fsdb(8)

FFS debugging/editing tool

## NAME

**fsdb** – FFS debugging/editing tool

## SYNOPSIS

**fsdb** \[**-d**\] **-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 file system (i-number 2).

The command processor uses the [editline(3)](/editline/3.md) 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:

- **-d**

  Enables additional debugging output (which comes primarily from [fsck(8)](/fsck/8.md)-derived code).

- **-f** *fsname*

  Open file system *fsname*.

Besides the built-in [editline(3)](/editline/3.md) 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.

- **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*.

- **chlen** *length*

  Change the length of the current inode to *length*.

- **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)](/editline/3.md), [fs(5)](/fs/5.md), [clri(8)](/clri/8.md), [fsck(8)](/fsck/8.md)

## HISTORY

**fsdb** uses the source code for [fsck(8)](/fsck/8.md) to implement most of the file system manipulation code. The remainder of **fsdb** first appeared in NetBSD 1.1.

## 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.

## WARNING

Use this tool with extreme caution – you can damage an FFS file system beyond what [fsck(8)](/fsck/8.md) can repair.