lsof

Identify processes using open files, network sockets, and devices on Linux.

6|1|Updated Feb 16, 2026
One-click install
npx skills add https://github.com/L3DigitalNet/Claude-Code-Plugins --skill lsof
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: lsof
Source: https://github.com/L3DigitalNet/Claude-Code-Plugins/tree/main/plugins/linux-sysadmin/skills/lsof
Command: npx skills add https://github.com/L3DigitalNet/Claude-Code-Plugins --skill lsof

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

This Skill helps you identify which processes are using specific files, directories, or network ports on your system, crucial for troubleshooting resource conflicts and understanding system activity.

Core Features & Use Cases

  • Identify Process Ownership: Determine which process has a particular file or network port open.
  • Network Troubleshooting: Diagnose "address already in use" errors by finding which process is listening on a port.
  • Disk Space Issues: Find deleted files that are still held open by processes, consuming disk space.
  • Use Case: If you're trying to unmount a directory and get a "resource busy" error, use this Skill to find out which process is still accessing files within it.

Quick Start

Use the lsof skill to find out which process is using port 8080.

Frequently Asked Questions about lsof

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I find which process is using a specific port?

This Skill identifies processes associated with open network sockets to help you find which process is using a specific port. It helps diagnose "address already in use" errors by finding which process is listening on that port.

How do I troubleshoot a resource busy error when unmounting a directory?

To troubleshoot a resource busy error, you identify processes still accessing files within the target directory. This Skill finds open files and devices on your Linux system, allowing you to close the associated processes and successfully unmount the directory.

Why does my Linux system show missing disk space after deleting files?

Missing disk space after deletion often occurs because processes still hold deleted files open. This Skill identifies processes associated with open files, allowing you to find deleted files that are still held open by processes and consuming disk space.

Does the lsof Skill require any specific software to be installed?

Yes, this Skill requires the lsof binary to be installed and executable on your Linux system. It uses this binary to identify processes associated with open files, network sockets, and devices for diagnosing resource contention.

How do I check file descriptor usage for a specific process?

To check file descriptor usage for a specific process, you identify the open files and devices associated with its process ID. This Skill helps you understand file descriptor usage by specific processes on a Linux system.