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MAN PAGE: CHATTR(1)Contents
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 +-=[ASacdisu].
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 `ASacdisu' select the new attributes for the
files: don't update atime (A), synchronous updates (S),
append only (a), compressed (c), immutable (i), no dump
(d), 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 pro
gram version.
-v version
Set the filesystem version.
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 com
pressed 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 can
not 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.
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.
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 <card@masi.ibp.fr>, the
developer and maintainer of the ext2 fs.
As of ext2 fs 0.5a, the `c' and `u' attribute are not hon
oured by the kernel code. As of the Linux 2.0 kernel, the
'A' attribute is not yet supported by the kernel code.
(The noatime code is still in testing.)
These attributes will be implemented in a future ext2 fs
version.
chattr is part of the e2fsprogs package and is available
for anonymous ftp from tsx-11.mit.edu in /pub/linux/pack
ages/ext2fs.
lsattr(1)
E2fsprogs version 1.18 November 1999 2 | 
