Inodes / Index Nodes

Inodes represent anything you can see in a UNIX or Linux filesystem. When we say there are files and directories we are sort of lying. There are really just inodes that point to different parts of memory — or no memory at all. For example, every running process is represented as an inode in the /proc/ pseudo filesystem.

⚠️ Running out of inodes is one of the rare things that will being even the most robust Linux system to a screeching halt. You’ll know it when it happens. Your terminal will fill with the dreaded “OUT OF INODES” messages. Every system administrator sees this at some point in their lives — hopefully only once.