"chattr" Command

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chattr (Change Attribute) is a command that is used to set/unset certain attributes of files/folders in Linux/Unix system to secure accidental deletion or modification of important files and folders, even though you have full permission over files. root user only can change the file attributes.

root:~# man chattr
          

The operator + causes the selected attributes to be added to the existing attributes of the files.
The operator - causes the selected attributes to be removed.
The operator = causes to be the only attributes that the files have.

The letters acdeijstuACDST 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), no Copy on write (C), 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 command but not modified by chattr: huge file (h), compression Error (E), Indexed directory (I), compression raw access (X), and compressed dirty file (Z).

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.

root:~# cat test.txt
This is Test File.
root:~# chattr +i test.txt
root:~# lsattr test.txt
----i----------- test.txt
root:~# rm test.txt
rm: cannot remove 'test.txt': Operation not permitted
root:~# echo "hello" >> test.txt
-bash: test.txt: Permission denied
root:~# chattr -i test.txt
root:~# lsattr test.txt
---------------- test.txt
root:~# rm test.txt
          

root:~# mkdir ABC
root:~# cd ABC
root:~# touch x y z
root:~# chattr -R +i ABC/
root:~# lsattr ABC/
----i----------- ABC/x
----i----------- ABC/y
----i----------- ABC/z
root:~# rm -rf ABC
rm: cannot remove 'ABC/x': Permission denied
rm: cannot remove 'ABC/y': Permission denied
rm: cannot remove 'ABC/z': Permission denied
root:~# chattr -R -i ABC
root:~# rm -rfv ABC/
removed 'ABC/x'
removed 'ABC/y'
removed 'ABC/z'
removed directory: 'ABC/'
          

root:~# cat test.txt
This is Test File.
root:~# lsattr test.txt
---------------- test.txt
root:~# chattr +a test.txt
root:~# lsattr test.txt
-----a---------- test.txt
root:~# echo "hello" > test.txt
-bash: test.txt: Operation not permitted
root:~# echo "hello" >> test.txt
root:~# cat test.txt
This is Test File.
hello
root:~#