NAME
    chattr - change file attributes on a Linux second extended file system

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

DESCRIPTION
    chattr changes the file attributes on a Linux second extended file sys-
    tem.

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

    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), compressed (c), no  dump (d), immutable
    (i), data journalling (j), secure deletion (s), top of directory hier-
    archy (T), no tail-merging (t), 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 program 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 sys-
    tems.

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

    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.

    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.

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

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

    The 'I' attribute is used by the htree code to indicate that a direc-
    tory is behind 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 `i' attribute cannot be modified: it cannot be deleted
    or renamed, no  link can be created to this file and no data can be
    written to the file. Only the superuser or a process pessessing the
    CAP_LINUX_IMMUTABLE capability can set or clear this attribute.

    A file with the `j' attribute has all of its data written to the ext3
    journal before being written to the file 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. Only the supe-
    ruser or a process possessing the CAP_SYS_RESOURCE capability can set
    or clear this attribute.

    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 directory with the 'T' attribute will be deemed to be the top of
    directory hierarchies for the  purposes of the Orlov block allocator
    (which is used in on systems with Linux 2.5.46 or later).

    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
    chattr is part  of the e2fsprogs package and is available from
    http://e2fsprogs.sourceforge.net.

SEE ALSO
   lsattr(1)