Provided by: e2fsprogs_1.46.5-2ubuntu2_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 +-=[aAcCdDeFijmPsStTux].

       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 'aAcCdDeFijmPsStTux' 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 journaling (j), don't compress  (m),  project  hierarchy  (P),  secure
       deletion  (s),  synchronous  updates  (S), no tail-merging (t), top of directory hierarchy
       (T), undeletable (u), and direct access for files (x).

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

       Not all flags are supported or utilized by all file systems; refer to file system-specific
       man pages such as btrfs(5), ext4(5), and xfs(5) for more file system-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      A file with the 'a' attribute set can only be opened in append  mode  for  writing.
              Only  the  superuser or a process possessing the CAP_LINUX_IMMUTABLE capability can
              set or clear this attribute.

       A      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.

       c      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.  (Note: For btrfs, If
              the  'c'  flag  is  set, then the 'C' flag cannot be set. Also conflicts with btrfs
              mount option 'nodatasum')

       C      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. If the 'C' flag is set, then the 'c' flag cannot be set.)

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

       D      When  a  directory  with the 'D' attribute set is modified, the changes are written
              synchronously to the disk; this is equivalent to the 'dirsync' mount option applied
              to a subset of the files.

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

       E      A file, directory, or symlink with the 'E' attribute set is encrypted by  the  file
              system.   This attribute may not be set or cleared using chattr(1), although it can
              be displayed by lsattr(1).

       F      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.

       i      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.

       I      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 cleared using chattr(1), although
              it can be displayed by lsattr(1).

       j      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  file  system  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.

       m      A  file  with  the  'm' attribute is excluded from compression on file systems that
              support per-file compression.

       N      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 cleared using chattr(1), although it
              can be displayed by lsattr(1).

       P      A directory with the 'P' attribute set will enforce a  hierarchical  structure  for
              project  id's.  This means that files and directories 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 ids must
              match.  In addition, a hard link to file can only be created when  the  project  id
              for the file and the destination directory match.

       s      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.

       S      When  a  file  with  the  'S'  attribute  set  is modified, the changes are written
              synchronously to the disk; this is equivalent to the 'sync' mount option applied to
              a subset of the files.

       t      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  file  systems  which  support  tail-
              merging).   This  is  necessary  for  applications such as LILO which read the file
              system directly, and which don't understand tail-merged files.  Note:  As  of  this
              writing, the ext2, ext3, and ext4 file systems do not support tail-merging.

       T      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.

       u      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.

       x      The 'x' attribute can be set on a directory or file.  If the attribute is set on an
              existing  directory,  it will be inherited by all files and subdirectories that are
              subsequently created in the directory.  If an existing directory has contained some
              files  and  subdirectories, modifying the attribute on the parent directory doesn't
              change the attributes on these files and subdirectories.

       V      A file with the 'V' attribute set has fs-verity enabled.  It cannot be written  to,
              and  the  file  system  will  automatically  verify all data read from it against a
              cryptographic hash that covers the entire file's contents, e.g. via a Merkle  tree.
              This  makes  it  possible to efficiently authenticate the file.  This attribute may
              not be set or cleared 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, ext3, and ext4 file systems
       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).