Provided by: e2fsprogs_1.45.3-4ubuntu1_amd64 bug

NAME

       chattr - change file attributes on a Linux file system

SYNOPSIS

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

DESCRIPTION

       chattr changes the file attributes on a Linux file system.

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

       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  'aAcCdDeFijPsStTu' select the new attributes for the files: append only (a),
       no atime updates (A), compressed (c), no copy on  write  (C),  no  dump  (d),  synchronous
       directory  updates  (D),  extent  format  (e),  case-insensitive  directory  lookups  (F),
       immutable  (i),  data  journalling  (j),  project  hierarchy  (P),  secure  deletion  (s),
       synchronous  updates  (S),  no  tail-merging  (t),  top  of  directory  hierarchy (T), and
       undeletable (u).

       The following attributes are read-only, and may be listed by lsattr(1) but not modified by
       chattr: encrypted (E), indexed directory (I), and inline data (N).

       Not  all  flags are supported or utilized by all filesystems; refer to filesystem-specific
       man pages such as btrfs(5), ext4(5), and xfs(5) for more filesystem-specific details.

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.

       -p project
              Set the file's project number.

ATTRIBUTES

       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.

       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 '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.

       A file with the 'C' attribute set will not be subject to copy-on-write updates.  This flag
       is  only supported on file systems which perform copy-on-write.  (Note: For btrfs, the 'C'
       flag should be set on new or empty files.  If it is set on a file which already  has  data
       blocks, it is undefined when the blocks assigned to the file will be fully stable.  If the
       'C' flag is set on a directory, it will have no effect on the  directory,  but  new  files
       created in that directory will have the No_COW attribute set.)

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

       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.

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

       A  directory  with  the  'F' attribute set indicates that all the path lookups inside that
       directory are made in a case-insensitive fashion.  This attribute can only be  changed  in
       empty directories on file systems with the casefold feature enabled.

       A file with the 'i' attribute cannot be modified: it cannot be deleted or renamed, no link
       can be created to this file, most of the file's metadata can not be modified, and the file
       can  not  be  opened  in  write  mode.   Only  the  superuser  or a process possessing the
       CAP_LINUX_IMMUTABLE capability can set or clear this attribute.

       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).

       A file with the 'j' attribute has all of its data written to  the  ext3  or  ext4  journal
       before  being  written  to  the  file  itself,  if  the  file  system  is mounted with the
       "data=ordered" or "data=writeback" options and the file system has a  journal.   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.

       A  file  with the 'N' attribute set indicates that the file has data stored inline, within
       the inode itself. It may not be set or reset using chattr(1), although it can be displayed
       by lsattr(1).

       A  directory  with the 'P' attribute set will enforce a hierarchical structure for project
       id's.  This means that files and directory created  in  the  directory  will  inherit  the
       project id of the directory, rename operations are constrained so when a file or directory
       is moved into another directory, that the project id's much match.  In  addition,  a  hard
       link  to  file  can  only  be created when the project id for the file and the destination
       directory match.

       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 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.

       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.

       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.

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, ext3, and ext4 filesystems
       as implemented in the current mainline Linux kernels.  Setting 'a' and 'i' attributes will
       not affect the ability to write to already existing file descriptors.

       The 'j' option is only useful for ext3 and ext4 file systems.

       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), btrfs(5), ext4(5), xfs(5).