> ## Documentation Index > Fetch the complete documentation index at: https://docs.domino.ai/llms.txt > Use this file to discover all available pages before exploring further. # The lsof utility - 'list open files' > Troubleshoot open files, network ports, and process locks on Linux using lsof basic and advanced command examples. **Version/Environment (if relevant):** Applicable to any Linux-based system including Domino deployments. ## Issue: Administrators and engineers need to identify processes holding file locks, investigate socket activity, or troubleshoot process ID (PID) conflicts on a Linux-based system. ## Root Cause: This is a reference article for the `lsof` utility. ## Resolution: ### What is lsof? `lsof` lists open files on Linux-based systems. It displays information about file descriptors and the processes that hold them open, including network connections and listening ports. Use `lsof` to identify processes holding file locks, investigate socket activity, and troubleshoot process ID (PID) conflicts. > ⚠️ **Prerequisite:** `lsof` may require privilege elevation to access files belonging to other users. Prepend `sudo` to any command when running as a non-root user. **Basic usage** Use the following commands to troubleshoot open files on a Linux system: Find all open files for a user: ``` lsof -u ``` Find all open files associated with a particular process using a PID: ``` lsof -p ``` List and locate all open socket files: ``` lsof +D / -a -d sock ``` Locate all open files listening on a specific port: ``` lsof -i : ``` Identify all open files linked to an application by program name: ``` lsof -c ``` **Advanced usage** Use these commands for more targeted investigation across processes, file descriptors, and time intervals: Display the process name, PID, and file name for all open files at a set time interval: ``` lsof -n -r