[Linux] Bash chattr Uso: Change file attributes on a Linux filesystem

Overview

The chattr command in Linux is used to change file attributes on a filesystem. It allows users to set or remove certain attributes that can affect how files are accessed or modified, providing an additional layer of security and control over file management.

Usage

The basic syntax of the chattr command is as follows:

chattr [options] [arguments]

Common Options

• +a: Append-only. Files can only be opened in append mode for writing.
• +i: Immutable. The file cannot be modified, deleted, or renamed.
• -a: Remove append-only attribute.
• -i: Remove immutable attribute.
• +e: Allow the file to be used for extents (for filesystems that support it).
• -e: Remove extent support.

Common Examples

1. Set a file as immutable:

   chattr +i myfile.txt
   

   This command makes myfile.txt immutable, preventing any changes to it.

2. Remove the immutable attribute:

   chattr -i myfile.txt
   

   This command allows modifications to myfile.txt again.

3. Set a file to append-only:

   chattr +a mylogfile.log
   

   This command allows mylogfile.log to be opened only in append mode.

4. Check current attributes of a file:

   lsattr myfile.txt
   

   This command displays the current attributes of myfile.txt.

5. Set multiple attributes at once:

   chattr +i +a myfile.txt
   

   This command makes myfile.txt both immutable and append-only.

Tips

• Use lsattr to check the current attributes of files before making changes.
• Be cautious when setting the immutable attribute, as it can prevent all modifications, including deletions.
• Consider using these attributes on critical system files to prevent accidental changes or deletions.