The chattr command in Linux is a file system command which is used for changing the attributes of a file in a directory. The primary use of this command is to make OS files unable to alter for users other than the superuser.
Here is the basic syntax for using chattr:
chattr [options] [attributes] [file or directory]
The options that can be used with chattr include:
+: add an attribute
-: remove an attribute
=: set the specified attributes and remove any others
The attributes that can be used with chattr include:
a: append mode, which prevents data from being overwritten in the file
i: immutable, which prevents the file from being deleted or modified
d: no dump, which prevents the file from being included in backups
s: secure deletion, which overwrites the file’s data with zeroes when it is deleted
To check the immutable flag:
lsattr file.txt
To make a file immutable (non-editable), you can use the following command:
chattr +i file.txt
To remove the immutable flag:
chattr -i file.txt
To check the immutable flag:
lsattr file.txt
A file with the `i’ attribute:
- Cannot be deleted or renamed.
- No link can be created to this file.
- No data can be written to the file.
- Only the superuser or a process possessing the CAP_LINUX_IMMUTABLE capability can set or clear this attribute.
- Even file owner can not edit/move/delete/update file.
Note: Only the root/superuser can use chattr command to modify an immutable file.
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