chattr − change file attributes on a Linux file system
chattr [ −RVf ] [ −v version ] [ mode ] files...
chattr changes the file attributes on a Linux file system.
The format of a symbolic mode is +-=[acdeijstuADST].
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 ‘acdeijstuADST’ select the new attributes for the files: append only (a), compressed (c), no
dump (d), extent format (e), immutable (i), data journalling (j), secure deletion (s), no tail-merging (t),
undeletable (u), no atime updates (A), synchronous directory updates (D), synchronous updates (S), and top
of directory hierarchy (T).
The following attributes are read-only, and may be listed by lsattr(1) but not modified by chattr: huge file
(h), compression error (E), indexed directory (I), compression raw access (X), and compressed dirty file
Recursively change attributes of directories and their contents.
Be verbose with chattr’s output and print the program version.
Suppress most error messages.
Set the file’s version/generation number.
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.
A file with the ‘a’ attribute set can only be open in append mode for writing. Only the superuser or a
process possessing 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. Note:
please make sure to read the bugs and limitations section at the end of this document.
When a directory with the ‘D’ attribute set is modified, the changes are written synchronously on the disk;
this is equivalent to the ‘dirsync