fsdb(8) - NetBSD Manual Pages

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FSDB(8)                 NetBSD System Manager's Manual                 FSDB(8)


NAME

     fsdb -- FFS debugging/editing tool


SYNOPSIS

     fsdb [-dFnN] -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.

     The -N option causes the superblock not to be marked dirty when fsdb
     exits.


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 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
     birthtime time
             Change the modification, change, access time, or birthtime
             (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, atimensec, or birthtimensec field will be
             set to zero.  The birthtime field is only available on ufs2
             filesystems.

     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 sys-
     tem 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.

NetBSD 10.1                      May 29, 2021                      NetBSD 10.1