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CHATTR(1)							     CHATTR(1)

NAME
       chattr - change file attributes on a Linux second extended file system

SYNOPSIS
       chattr [ -RV ] [ -v version ] [ mode ] files...

DESCRIPTION
       chattr changes the file attributes on a Linux second extended file sys‐
       tem.

       The format of a symbolic mode is +-=[ASacDdIijsTtu].

       The operator `+' causes the selected attributes	to  be	added  to  the
       existing	 attributes  of	 the files; `-' causes them to be removed; and
       `=' causes them to be the only attributes that the files have.

       The letters `acdijsuADST' select the  new  attributes  for  the	files:
       append only (a), compressed (c), no dump (d), immutable (i), data jour‐
       nalling (j), secure deletion (s), no tail-merging (t), undeletable (u),
       no  atime  updates  (A), synchronous directory updates (D), synchronous
       updates (S), and top of directory hierarchy (T).

OPTIONS
       -R     Recursively change attributes of directories and their contents.
	      Symbolic links encountered during recursive directory traversals
	      are ignored.

       -V     Be verbose with chattr's output and print the program version.

       -v version
	      Set the file's version/generation number.

ATTRIBUTES
       When a file with the 'A' attribute set is accessed, its atime record is
       not modified.  This avoids a certain amount of disk I/O for laptop sys‐
       tems.

       A file with the `a' attribute set can only be open in append  mode  for
       writing.	   Only	  the	superuser   or	 a   process   possessing  the
       CAP_LINUX_IMMUTABLE capability can set or clear this attribute.

       A file with the `c' attribute set is automatically  compressed  on  the
       disk  by	 the kernel.  A read from this file returns uncompressed data.
       A write to this file compresses data before storing them on  the	 disk.
       Note:  please make sure to read the bugs and limitations section at the
       end of this document.

       When a directory with the `D' attribute set is  modified,  the  changes
       are  written  synchronously  on	the  disk;  this  is equivalent to the
       `dirsync' mount option applied to a subset of the files.

       A file with the `d' attribute set is not candidate for backup when  the
       dump(8) program is run.

       The  'E'	 attribute  is used by the experimental compression patches to
       indicate that a compressed file has a compression error.	 It may not be
       set  or	reset  using  chattr(1),  although  it	can  be	 displayed  by
       lsattr(1).

       The 'I' attribute is used by the htree code to indicate that  a	direc‐
       tory  is behind indexed using hashed trees.  It may not be set or reset
       using chattr(1), although it can be displayed by lsattr(1).

       A file with the `i' attribute cannot be modified: it cannot be  deleted
       or  renamed,  no	 link  can  be created to this file and no data can be
       written to the file.  Only the superuser or a  process  possessing  the
       CAP_LINUX_IMMUTABLE capability can set or clear this attribute.

       A  file	with the `j' attribute has all of its data written to the ext3
       journal before being written to the file itself, if the	filesystem  is
       mounted	with the "data=ordered" or "data=writeback" options.  When the
       filesystem is mounted with the "data=journal" option all file  data  is
       already	journalled  and	 this attribute has no effect.	Only the supe‐
       ruser or a process possessing the CAP_SYS_RESOURCE capability  can  set
       or clear this attribute.

       When  a	file  with  the	 `s'  attribute set is deleted, its blocks are
       zeroed and written back to the disk.  Note: please make	sure  to  read
       the bugs and limitations section at the end of this document.

       When  a	file  with  the `S' attribute set is modified, the changes are
       written synchronously on the disk; this is  equivalent  to  the	`sync'
       mount option applied to a subset of the files.

       A  directory  with  the	'T'  attribute will be deemed to be the top of
       directory hierarchies for the purposes of  the  Orlov  block  allocator
       (which is used in on systems with Linux 2.5.46 or later).

       A file with the 't' attribute will not have a partial block fragment at
       the end of the file merged with	other  files  (for  those  filesystems
       which  support  tail-merging).  This is necessary for applications such
       as LILO which read the filesystem directly, and which don't  understand
       tail-merged files.  Note: As of this writing, the ext2 or ext3 filesys‐
       tems do not (yet, except in very experimental  patches)	support	 tail-
       merging.

       When  a	file  with  the `u' attribute set is deleted, its contents are
       saved.  This allows the user to ask for its undeletion.	 Note:	please
       make  sure  to read the bugs and limitations section at the end of this
       document.

       The 'X' attribute is used by the experimental  compression  patches  to
       indicate	 that  a  raw  contents	 of  a compressed file can be accessed
       directly.  It currently may  not	 be  set  or  reset  using  chattr(1),
       although it can be displayed by lsattr(1).

       The  'Z'	 attribute  is used by the experimental compression patches to
       indicate a compressed file is dirty.  It may not be set or reset	 using
       chattr(1), although it can be displayed by lsattr(1).

AUTHOR
       chattr was written by Remy Card <Remy.Card@linux.org>.  It is currently
       being maintained by Theodore Ts'o <tytso@alum.mit.edu>.

BUGS AND LIMITATIONS
       The `c', 's',  and `u' attributes are not honored by the ext2 and  ext3
       filesystems  as	implemented  in	 the  current  mainline Linux kernels.
       These attributes may be implemented in future versions of the ext2  and
       ext3 filesystems.

       The `j' option is only useful if the filesystem is mounted as ext3.

       The `D' option is only useful on Linux kernel 2.5.19 and later.

AVAILABILITY
       chattr  is  part	 of  the  e2fsprogs  package  and  is  available  from
       http://e2fsprogs.sourceforge.net.

SEE ALSO
       lsattr(1)

E2fsprogs version 1.39		   May 2006			     CHATTR(1)
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