Provided by: e2fsprogs_1.42-1ubuntu2_amd64 bug

NAME

       chattr - change file attributes on a Linux file system

SYNOPSIS

       chattr [ -RVf ] [ -v version ] [ mode ] files...

DESCRIPTION

       chattr changes the file attributes on a Linux file system.

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

       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  `acdeijstuADST'  select  the  new attributes for the files: append only (a),
       compressed (c), no dump (d), extent format  (e),  immutable  (i),  data  journalling  (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).

       The following attributes are read-only, and may be listed by lsattr(1) but not modified by
       chattr: huge file (h), compression error  (E),  indexed  directory  (I),  compression  raw
       access (X), and compressed dirty file (Z).

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 systems.

       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 'e' attribute indicates that the file is using extents for mapping the blocks on disk.
       It may not be removed using chattr(1).

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

       The  'h'  attribute  indicates  the  file is storing its blocks in units of the filesystem
       blocksize instead of in units of sectors, and means that the file is (or at one time  was)
       larger than 2TB.  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 superuser
       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.  This is a hint to the block allocator used
       by ext3 and ext4 that the subdirectories under this directory are not  related,  and  thus
       should  be  spread  apart for allocation purposes.   For example it is a very good idea to
       set the 'T' attribute on the /home directory, so that /home/john and /home/mary are placed
       into  separate  block  groups.  For directories where this attribute is not set, the Orlov
       block allocator will try to group subdirectories closer together where possible.

       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
       filesystems 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)