Linux Command - fuser

The Linux fuser command shows the PIDs of all processes that are acessing a specific file or file system. It will display a list of pids and the type of access they have.

NOTE:

• Run as root to see everything.
• Access by the kernel is only shown with the -v option.

Basic usage:

fuser /home/user1     # show all procs acessing this file
fuser -m /home/user1     # show all procs acessing any file on same FS as this file
fuser -u /home/user1   #  include user id
fuser -v /home/user1   #  verbose, columns with  info

Killing processes:

fuser -k /data1       # kill all procs acessing this file
fuser -ki /data1      # same but interactive
fuser -kM /data1      # same but only if it is a mountpoint ( for safety )
fuser -kMi /data1     # more safe ( mountpoint only and interactive )
fuser -kw  /data1     # only kill procs with write access

fuser -km /data1      # kill all processes acessing FS that this file is on
fuser -kmM /data1     # same but only if mountpoint

List signal names:

fuser -l

Showing TCP / UDP network ports:

sudo fuser -n tcp http/tcp   # TCP port 80
sudo fuser -n tcp 80         # TCP port 80

sudo fuser -k -n tcp 80      # TCP port 80 - kill procs on this port
sudo fuser -u -n tcp 80      # TCP port 80 with users
sudo fuser -v -n tcp 80      # TCP port 80 verbose

sudo fuser -n udp 53         # UDP port 53

Type of access:

c	current directory.
e	executable being run.
f	open file. f is omitted in default display mode.
F	open file for writing. F is omitted in default display mode.
r	root directory.
m	mmap’ed file or shared library.
.	Placeholder, omitted in default display mode.

Parameters:

-a	show all files even if not accessed
-c	same as -m
-f	does nothing
-k	kill ( SIGKILL )
-i	interactve, ask before kill
-I	use inodes instead of names
-l	list signal names
-m name	list procs for all files on same FS as this file
-M	only run request if mountpoint has been specified ( for safety )
-w	only kill processes with write access
-n	namespace (file, udp, tcp )
-s	silent ( -u and -v ignored, don’t use with -a )
-SIGNAL	alternate signal instead of SIGKILL ex: -HUP or -1
-u	show username
-v	verbose
-V	version
-4	only IPv4
-6	only IPv6