jfs_debugfs (8) Linux Manual Page
jfs_debugfs – shell-type JFS file system editor
Synopsis
jfs_debugfs device
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.
See Also
jfs_fsck(8), jfs_mkfs(8), jfs_fscklog(8), jfs_logdump(8), jfs_tune(8),
Authors
Barry Arndt (barndt [at] us.ibm.com) William Braswell, Jr.
jfs_debugfs is maintained by IBM.
See the JFS project web site for more details: http://jfs.sourceforge.net/