fuser (Unix)

The Unix command fuser is used to show which processes are using a specified file, file system, or unix socket. For example, to check process IDs and users accessing a USB drive:

$ fuser -m -u /mnt/usb1
/mnt/usb1:   1347c(root)  1348c(guido)  1349c(guido)

The command displays the process identifiers of processes using the specified files or file systems. In the default display mode, each file name is followed by a letter denoting the type of access:

c: current directory.
e: executable being run.
f: open file.
F: open file for writing.
r: root directory.
m: mmap'ed file or shared library

The command can also be used to check what processes are using a network port:

$ fuser -v -n tcp 80
                     USER        PID ACCESS COMMAND
80/tcp:              root       3067 F.... (root)httpd
                     apache     3096 F.... (apache)httpd
                     apache     3097 F.... (apache)httpd

The command returns a non-zero code if none of the files are accessed or in case of a fatal error. If at least one access has succeeded, fuser returns zero. The output of "fuser" may be useful in diagnosing "resource busy" messages arising when attempting to unmount filesystems.

Options

-k: kills all process accessing a file. For example, fuser -k /path/to/your/filename kills all processes accessing this directory without confirmation. Use -i for confirmation
-i: interactive mode. Prompt before killing process
-v: verbose.
-u: append username
-a: display all files
-m: name specifies a file on a mounted file system or a block device that is mounted. All processes accessing files on that file system are listed. If a directory file is specified, it is automatically changed to name/. to use any file system that might be mounted on that directory.

Also, note that -k sends a SIGKILL to all process. Use the -signal to send a different signal. For a list of signals supported by the fuser run 'fuser -l'

Related commands

The list of all open files and the processes that have them open can be obtained through the lsof command.
The equivalent command on BSD operating systems is fstat(1)

External links

fuser – Commands & Utilities Reference, The Single UNIX® Specification, Issue 7 from The Open Group

Unix command-line interface programs and shell builtins

File system	cat chmod chown chgrp cksum cmp cp dd du df file fsck fuser ln ls mkdir mount mv pax pwd rm rmdir split tee touch type umask

Processes	at bg chroot cron fg kill killall nice pgrep pkill ps pstree time top

User environment	clear env exit finger history logname mesg passwd su sudo uptime talk tput uname w wall who whoami write

Text processing	awk banner basename comm csplit cut diff dirname ed ex fmt fold head iconv join less more nl paste printf sed sort spell strings tail tr uniq vi wc xargs yes

Shell builtins	alias cd echo test unset wait

Networking	dig host ifconfig inetd netcat netstat nslookup ping rdate rlogin route ssh traceroute

Searching	find grep locate whatis whereis

Documentation	apropos help man

Miscellaneous	bc dc cal expr lp od sleep true and false

List of Unix commands

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