fuser

fuser Plugin

Identify processes using files, sockets, or filesystems. Essential for debugging file locking, port conflicts, and resource contention issues.

Commands

File & Socket Inspection

• fuser file check <path> — Identify processes using a file or socket
• fuser tcp port <port> — Find processes using a specific TCP port
• fuser self version — Show fuser version info
• fuser _ _ <args> — Passthrough to fuser CLI

Usage Examples

• "Check what process is using file /var/log/syslog"
• "Find which process is using port 8080"
• "Kill all processes using /dev/ttyUSB0"

Installation

# Pre-installed on most Linux systems
# If missing:
apt-get install util-linux
supercli plugins install ./plugins/fuser --on-conflict replace --json

Examples

# Check what process is using a file
fuser -v /var/log/syslog

# Find processes using TCP port 8080
fuser -v 8080/tcp

# Kill processes using a file
fuser -k /path/to/file

# Find processes on a mount point
fuser -vm /mnt/data

# List processes using IPC resources
fuser -v --ipc /dev/shm/some-file

Key Features

• Identify PIDs using files, sockets, and filesystems
• Kill processes blocking resources
• TCP/UDP port conflict resolution
• Mount point usage inspection
• IPC resource tracking