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CHATTR(1)							     CHATTR(1)



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

SYNOPSIS
       chattr [ -RVf ] [ -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.

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

       -f     Suppress most error messages.

       -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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