Provided by: e2fsprogs_1.45.6-1ubuntu1_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 +-=[aAcCdDeFijPsStTu].

       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), inline data (N), and verity (V).

       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      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.

       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.)

       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
              filesystem.   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  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.

       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  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, ext3, and ext4 filesystems 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.

       V      A  file with the 'V' attribute set has fs-verity enabled.  It cannot be written to,
              and the filesystem 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  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).