File systems

Set default file permissions on Linux with umask

Learn how to use umask to set the default file permissions in Linux. We look at examples, including how and where to implement them.

How to monitor disk activity (I/O) on Linux

Learn how to monitor a Linux system and focus on disk activity with tools like iotop, sar, vmstat, or iostat.

How to see the file type on Linux

Learn how to see the file type of normal and special files on a Linux system by using the file command.

How to see the size of a file

Learn how to see the size of a file on Linux systems using the ls or stat command.

How to display directory contents sorted by modification time

Learn how to sort the output of the ls command to list a directory contents by its modification time.

How to see the size of a directory

Learn how to see the size of a directory or folder on Linux systems using the du command.

How to see hidden files

Learn how to see any hidden files on the command line or in the terminal using the ls command.

How to see files great than a specific size

Learn how to see files smaller or bigger than a specific defined size on Linux, using the du command.

How to find when the last modification happened in a directory

Learn how to find the last modification time of a file or subdirectory in a specified directory on Linux.

How to see inode usage

Learn how to see inode usage on a Linux file system or mount point.

How to see used and free disk space

Learn how to see used and disk space of file systems or mount point on Linux systems.

How to find symbolic links that point to a directory

Learn how to use the find command to discover symbolic links that refer to a directory.

How to compare two directories and find the differences

Learn how to compare two directories and see their differences or what files they are having in common.

How to securely delete a file and its contents

Need to delete the contents of a sensitive file? Instead of just deleting it with rm, look at this option first.

How to see the creation date of a file

Learn how to use the stat command to find the initial creation time of a file, also known as its birth time.

Understanding the output of the stat command

Learn everything about the output that the stat command returns. Great for forensics, intrusion detection, and system administration.

How to change file permissions

Learn how to change the file permissions of files and directories on a Linux system. Follow the examples and make your system more secure.

Linux file permissions

Learn the basics of file permissions on Linux systems and common filesystems such as ext4, XFS, and ZFS. Guided by examples, everyone is able to learn how they work.

Introduction in Linux file permissions

Learn the basics of how a Linux system applies file permissions. We look at examples to demystify the permissions mean and learn to troubleshoot common issues.

How to find hard links or files that point to a specific file

Learn how to find hardlinks on a file system or which files they have in common. We will use the find command to get this information quickly available.

Linux file systems

All articles about the purpose of a file system and how it works. Learn how to become a specialist to further secure your system.

Linux system hardening: adding hidepid to /proc mount point

The pseudo-filesystem /proc contains a lot of useful information for the system administrator. With the hidepid option we can restrict what users can see.

Linux History: How Dot Files Became Hidden Files

Ever wondered why there are files on your Linux system, starting with a dot? The short answer: they are shortcuts. Here is the full story.

Using xattrs or Extended Attributes on Linux

Linux supports extended attributes (xattr) on most file systems. Learn how they work and allow security features like access control lists and more.

Plus sign in ls output

When file access control lists, or ACLs are being used, the output of ls will change. Learn about the additional plus sign in its output.