SYNOPSIS

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


DESCRIPTION

       chattr changes the  file  attributes  on  a  Linux  second
       extended file system.

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

       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 `ASacDdijsu' select the new attributes for the
       files:  don't  update  atime (A), synchronous updates (S),
       synchronous directory updates (D), append only  (a),  com­
       pressed  (c), no dump (d), immutable (i), data journalling
       (j), secure deletion (s), and undeletable (u).


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  pro­
              gram 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 systems.

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

       A  file  with  the `c' attribute set is automatically com­
       pressed 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.

       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 sub­
       set of the files.

       A  file  with  the  `d' attribute set is not candidate for
       itself,  if   the   filesystem   is   mounted   with   the
       "data=ordered"  or  "data=writeback"  options.   When  the
       filesystem is mounted with  the  "data=journalled"  option
       all file data is already journalled and this attribute has
       no effect.

       When a file with the `s' attribute  set  is  deleted,  its
       blocks are zeroed and written back to the disk.

       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 file with the 't' attribute  will  not  have  a  partial
       block  fragment at the 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 who don't understand  tail-merged
       files.

       When  a  file  with  the `u' attribute set is deleted, its
       contents are saved.  This allows the user to ask  for  its
       undeletion.

       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>.


BUGS AND LIMITATIONS

       As of Linux 2.2, the `c', 's',  and `u' attribute are  not
       honored by the kernel filesystem code.    These attributes
       will be implemented in a future ext2 fs version.

       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



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