fuser

Find processes accessing a file or directory

$ fuser path/to/file

$ fuser -v path/to/file

$ fuser 80/tcp

$ fuser 53/udp

$ fuser -k path/to/file

$ fuser -m /mnt/usb

$ fuser -k 8080/tcp

fuser [-fuv] [-a|-s] [-4|-6] [-c|-m|-n space] [-k [-i] [-SIGNAL]] name...

fuser displays the PIDs of processes using specified files or file systems. It can identify which processes have files open, executables running, or sockets in use, and optionally terminate them.

-a, --all

Display all specified files, including those not accessed

Kill processes accessing the file (SIGKILL by default)

Ask for confirmation before killing

Target processes accessing a mounted filesystem

Only match if target is a mount point

Select namespace: file, tcp, or udp

Include process owner usernames

Display processes in ps-like format

Operate silently

Search IPv4 sockets only

Search IPv6 sockets only

Send specified signal instead of SIGKILL

List available signal names

c: Current directory
e: Executable being run
f: Open file
F: Open file for writing
r: Root directory
m: Memory-mapped file or shared library

The -k option kills processes with SIGKILL by default, which cannot be caught. Use -i to confirm before killing. Root privileges may be needed to see all processes.

fuser is part of the psmisc package, providing tools for managing processes by file access.

lsof(8), kill(1), killall(1), ps(1)