Provided by: e2fsprogs_1.44.4-2_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 'aAcCdDeijPsStTu' 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), 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 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).