chattr - change file attributes on a Linux second extended file system
chattr [ -RV ] [ -v version ] [ mode ] files...
chattr changes the file attributes on a Linux second extended file system.
The format of a symbolic mode is +-=[ASacdistu].
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 `ASacdijsu' select the new attributes for the files: don't
update atime (A), synchronous updates (S), append only (a), compressed
(c), no dump (d), immutable (i), data journalling (j), secure deletion
(s), and undeletable (u).
-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.
When a file with the 'A' attribute set is modified, its atime record is
not modified. This avoids a certain amount of disk I/O for laptop systems.
A file with the `a' attribute set can only be open in append mode for
writing. Only the superuser 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.
A file with the `d' attribute set is not candidate for backup when the
dump(8) program is run.
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 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.
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 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 tailmerged
files.
When a file with the `u' attribute set is deleted, its contents are
saved. This allows the user to ask for its undeletion.
chattr was written by Remy Card <Remy.Card@linux.org>.
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.
chattr is part of the e2fsprogs package and is available from
http://e2fsprogs.sourceforge.net.
lsattr(1)
E2fsprogs version 1.27 March 2002 CHATTR(1)
[ Back ] | 