SYNOPSIS

DESCRIPTION

jfs_debugfs is a program which can be used to perform various low-level actions on a JFS formatted device.

device is the special file name corresponding to the actual device to be edited (e.g. /dev/hdb1).

jfs_debugfs must be run as root.

COMMANDS

a[lter] <block> <offset> <hex_string>

 replaces the data located at the <offset> of <block> with <hex_string>

<block> is the block number - given in decimal

<offset> is the offset within that block - given in hexadecimal

<hex_string> is an even-numbered string of hexadecimal digits to write to the disk

b[tree] <block> [<offset>]

* not implemented yet *
 displays one node of the btree located at <offset> of <block> and enters a subcommand mode to navigate the btree

SUBCOMMANDS:
 l => visit left sibling
 m => modify current node
 p => visit parent node
 r => visit right sibling
 [0-9] => visit the n'th child node
 x => exit subcommand mode

cb[blfsck]

 displays the area used by ClearBadBlockList for communication with fsck

SUBCOMMANDS:
 m => modify entries
 x => exit subcommand mode

dir[ectory] <inode_number> [<file_set>]

 displays the directory entries at <inode_number> and enters subcommand mode

<inode_number> is the directory's inode - given in decimal

<file_set> currently must be zero

SUBCOMMANDS:
 m => modify entries
 x => exit subcommand mode

d[isplay] [<block> [<offset> [<format> [<count>]]]]

displays <count> objects located at the <offset> of <block> in <format>

<block> is the block number - given in decimal

<offset> is the offset within <block> - given in hexadecimal

<format> is one of the following:
 a => ascii
 b => block allocation map
 d => decimal
 i => inode
 I => inode allocation map
 s => superblock
 x => hexadecimal
 X => extent allocation descriptor

<count> is the number of objects to display - given in decimal

dm[ap]

 displays aggregate disk (block) map

SUBCOMMANDS
 m => modify map fields
 f => display free count
 t => display tree levels
 x => exit subcommand mode

dt[ree] <inode_number> [<file_set>]

 displays root of the directory btree located at <inode_number> and enters a subcommand mode to navigate the btree

<inode_number> is the directory's inode - given in decimal

<file_set> currently must be zero

SUBCOMMANDS
 l => visit left sibling
 m => modify current node
 p => visit parent node (not parent directory)
 r => visit right sibling
 [0-9] => visit the n'th child node
 x => exit subcommand mode

fsckw[sphdr]

 displays the header of the fsck workspace in the aggregate

SUBCOMMANDS:
 m => modify entries
 x => exit subcommand mode

h[elp] [<command>]

 displays help for <command>
 if no command is given, all possible commands are displayed

ia[g] [<IAG_number>] [a | s | <file_set>]

 displays IAG information for <IAG_number> and enters subcommand mode

<IAG_number> is given in decimal

a is to use the primary aggregate inode table

s is to use the secondary aggregate inode table

<file_set> currently must be zero

SUBCOMMANDS
 e => display/modify inode extents map
 m => modify IAG
 p => display/modify persistent map
 w => display/modify working map
 x => exit subcommand mode

i[node] [<inode_number>] [a | s | <file_set>]

 displays inode information for <inode_number> and enters subcommand mode

<inode_number> is given in decimal

a is to use the primary aggregate inode table

s is to use the secondary aggregate inode table

<file_set> currently must be zero

SUBCOMMANDS
 a => display/modify inode's ACL
 m => modify inode
 x => exit subcommand mode

logs[uper]

 displays the journal log superblock and enters subcommand mode

SUBCOMMANDS
 m => modify journal log superblock
 x => exit subcommand mode

q[uit]

 exits jfs_debugfs

se[t] [<variable> <value>]

* not implemented yet *
 set user-defined <variable> to <value>
 if no arguments are given, displays all set variables

<variable> must begin with an alphabetic character

su[perblock] [p | s]

 displays superblock data

p displays the primary superblock

s displays the secondary superblock

SUBCOMMANDS:
 m => modify entries
 x => exit subcommand mode

s2p[erblock] [p | s]

 displays alternate superblock data

p displays the primary superblock

s displays the secondary superblock

SUBCOMMANDS:
 m => modify entries
 x => exit subcommand mode

u[nset] <variable>

* not implemented yet *
 deletes user-defined <variable>

xt[ree] <inode_number> [<file_set>]

 displays root of the non-directory btree located at <inode_number> and enters a subcommand mode to navigate the btree

<inode_number> is the directory's inode - given in decimal

<file_set> currently must be zero

SUBCOMMANDS
 l => visit left sibling
 m => modify current node
 p => visit parent node (not parent directory)
 r => visit right sibling
 [0-9] => visit the n'th child node
 x => exit subcommand mode

REPORTING BUGS

If you find a bug in JFS or jfs_debugfs, please report it via the bug tracking system ("Report Bugs" section) of the JFS project web site:

http://jfs.sourceforge.net/

Please send as much pertinent information as possible, including the complete output of running jfs_fsck with the -v and -n options on the JFS device.

AUTHORS

Barry Arndt  ([email protected])
William Braswell, Jr.

See the JFS project web site for more details:
http://jfs.sourceforge.net/