-? -h These two equivalent options select a usage (help) output list. Lsof displays a shortened form
of this output when it detects an error in the options supplied to it, after it has displayed
messages explaining each error. (Escape the `?' character as your shell requires.)
-a This option causes list selection options to be ANDed, as described above.
-A A This option is available on systems configured for AFS whose AFS kernel code is implemented via
dynamic modules. It allows the lsof user to specify A as an alternate name list file where the
kernel addresses of the dynamic modules might be found. See the lsof FAQ (The FAQ section gives
its location.) for more information about dynamic modules, their symbols, and how they affect
-b This option causes lsof to avoid kernel functions that might block - lstat(2), readlink(2), and
See the BLOCKS AND TIMEOUTS and AVOIDING KERNEL BLOCKS sections for information on using this
-c c This option selects the listing of files for processes executing the command that begins with
the characters of c. Multiple commands may be specified, using multiple -c options. They are
joined in a single ORed set before participating in AND option selection.
If c begins with a '^', then the following characters specify a command name whose processes are
to be ignored (excluded.)
If c begins and ends with a slash ('/'), the characters between the slashes are interpreted as a
regular expression. Shell meta-characters in the regular expression must be quoted to prevent
their interpretation by the shell. The closing slash may be followed by these modifiers:
b the regular expression is a basic one.
i ignore the case of letters.
x the regular expression is an extended one
See the lsof FAQ (The FAQ section gives its location.) for more information on basic and
extended regular expressions.
The simple command specification is tested first. If that test fails, the command regular
expression is applied. If the simple command test succeeds, the command regular expression test
isn't made. This may result in ``no command found for regex:'' messages when lsof's -V option
+c w This option defines the maximum number of initial characters of the name, supplied by the UNIX
dialect, of the UNIX command associated with a process to be printed in the COMMAND column.
(The lsof default is nine.)
Note that many UNIX dialects do not supply all command name characters to lsof in the files and
structures from which lsof obtains command name. Often dialects limit the number of characters
supplied in those sources. For example, Linux 2.4.27 and Solaris 9 both limit command name
length to 16 characters.
If w is zero ('0'), all command characters supplied to lsof by the UNIX dialect will be printed.
If w is less than the length of the column title, ``COMMAND'', it will be raised to that length.
-C This option disables the reporting of any path name components from the kernel's name cache.
See the KERNEL NAME CACHE section for more information.
+d s This option causes lsof to search for all open instances of directory s and the files and
directories it contains at its top level. This option does NOT descend the directory tree,
rooted at s. The +D D option may be used to request a full-descent directory tree search,
rooted at directory D.
Processing of the +d option does not follow symbolic links within s unless the -x or -x l
option is also specified. Nor does it search for open files on file system mount points on
subdirectories of s unless the -x or -x f option is also specified.
Note: the authority of the user of this option limits it to searching for files that the user
has permission to examine with the system stat(2) function.
-d s This option specifies a list of file descriptors (FDs) to exclude from or include in the output
listing. The file descriptors are specified in the comma-separated set s - e.g., ``cwd,1,3'',
``^6,^2''. (There should be no spaces in the set.)
The list is an exclusion list if all entries of the set begin with '^'. It is an inclusion list
if no entry begins with '^'. Mixed lists are not permitted.
A file descriptor number range may be in the set as long as neither member is empty, both
members are numbers, and the ending member is larger than the starting one - e.g., ``0-7'' or
``3-10''. Ranges may be specified for exclusion if they have the '^' prefix - e.g., ``^0-7''
excludes all file descriptors 0 through 7.
Multiple file descriptor numbers are joined in a single ORed set before participating in AND
When there are exclusion and inclusion members in the set, lsof reports them as errors and exits
with a non-zero return code.
See the description of File Descriptor (FD) output values in the OUTPUT section for more
information on file descriptor names.
+D D This option causes lsof to search for all open instances of directory D and all the files and
directories it contains to its complete depth.
Processing of the +D option does not follow symbolic links within D unless the -x or -x l
option is also specified. Nor does it search for open files on file system mount points on
subdirectories of D unless the -x or -x f option is also specified.
Note: the authority of the user of this option limits it to searching for files that the user
has permission to examine with the system stat(2) function.
Further note: lsof may process this option slowly and require a large amount of dynamic memory
to do it. This is because it must descend the entire directory tree, rooted at D, calling
stat(2) for each file and directory, building a list of all the files it finds, and searching
that list for a match with every open file. When directory D is large, these steps can take a
long time, so use this option prudently.
-D D This option directs lsof's use of the device cache file. The use of this option is sometimes
restricted. See the DEVICE CACHE FILE section and the sections that follow it for more
information on this option.
-D must be followed by a function letter; the function letter may optionally be followed by a
path name. Lsof recognizes these function letters:
? - report device cache file paths
b - build the device cache file
i - ignore the device cache file
r - read the device cache file
u - read and update the device cache file
The b, r, and u functions, accompanied by a path name, are sometimes restricted. When these
functions are restricted, they will not appear in the description of the -D option that
accompanies -h or -? option output. See the DEVICE CACHE FILE section and the sections that
follow it for more information on these functions and when they're restricted.
The ? function reports the read-only and write paths that lsof can use for the device cache
file, the names of any environment variables whose values lsof will examine when forming the
device cache file path, and the format for the personal device cache file path. (Escape the `?'
character as your shell requires.)
When available, the b, r, and u functions may be followed by the device cache file's path. The
standard default is .lsof_hostname in the home directory of the real user ID that executes lsof,
but this could have been changed when lsof was configured and compiled. (The output of the -h
and -? options show the current default prefix - e.g., ``.lsof''.) The suffix, hostname, is
the first component of the host's name returned by gethostname(2).
When available, the b function directs lsof to build a new device cache file at the default or
The i function directs lsof to ignore the default device cache file and obtain its information
about devices via direct calls to the kernel.
The r function directs lsof to read the device cache at the default or specified path, but
prevents it from creating a new device cache file when none exists or the existing one is
improperly structured. The r function, when specified without a path name, prevents lsof from
updating an incorrect or outdated device cache file, or creating a new one in its place. The r
function is always available when it is specified without a path name argument; it may be
restricted by the permissions of the lsof process.
When available, the u function directs lsof to read the device cache file at the default or
specified path, if possible, and to rebuild it, if necessary. This is the default device cache
file function when no -D option has been specified.
f by itself clarifies how path name arguments are to be interpreted. When followed by c, f, g,
G, or n in any combination it specifies that the listing of kernel file structure information is
to be enabled (`+') or inhibited (`-').
Normally a path name argument is taken to be a file system name if it matches a mounted-on
directory name reported by mount(8), or if it represents a block device, named in the mount
output and associated with a mounted directory name. When +f is specified, all path name
arguments will be taken to be file system names, and lsof will complain if any are not. This
can be useful, for example, when the file system name (mounted-on device) isn't a block device.
This happens for some CD-ROM file systems.
When -f is specified by itself, all path name arguments will be taken to be simple files. Thus,
for example, the ``-f -- /'' arguments direct lsof to search for open files with a `/' path
name, not all open files in the `/' (root) file system.
Be careful to make sure +f and -f are properly terminated and aren't followed by a character
(e.g., of the file or file system name) that might be taken as a parameter. For example, use
``--'' after +f and -f as in these examples.
$ lsof +f -- /file/system/name
$ lsof -f -- /file/name
The listing of information from kernel file structures, requested with the +f [cfgGn] option
form, is normally inhibited, and is not available in whole or part for some dialects - e.g.,
/proc-based Linux kernels below 2.6.22. When the prefix to f is a plus sign (`+'), these
characters request file structure information:
c file structure use count (not Linux)
f file structure address (not Linux)
g file flag abbreviations (Linux 2.6.22 and up)
G file flags in hexadecimal (Linux 2.6.22 and up)
n file structure node address (not Linux)
When the prefix is minus (`-') the same characters disable the listing of the indicated values.
File structure addresses, use counts, flags, and node addresses may be used to detect more
readily identical files inherited by child processes and identical files in use by different
processes. Lsof column output can be sorted by output columns holding the values and listed to
identify identical file use, or lsof field output can be parsed by an AWK or Perl post-filter
script, or by a C program.
-F f This option specifies a character list, f, that selects the fields to be output for processing
by another program, and the character that terminates each output field. Each field to be
output is specified with a single character in f. The field terminator defaults to NL, but may
be changed to NUL (000). See the OUTPUT FOR OTHER PROGRAMS section for a description of the
field identification characters and the field output process.
When the field selection character list is empty, all standard fields are selected (except the
raw device field, security context and zone field for compatibility reasons) and the NL field
terminator is used.
When the field selection character list contains only a zero (`0'), all fields are selected
(except the raw device field for compatibility reasons) and the NUL terminator character is
Other combinations of fields and their associated field terminator character must be set with
explicit entries in f, as described in the OUTPUT FOR OTHER PROGRAMS section.
When a field selection character identifies an item lsof does not normally list - e.g., PPID,
selected with -R - specification of the field character - e.g., ``-FR'' - also selects the
listing of the item.
When the field selection character list contains the single character `?', lsof will display a
help list of the field identification characters. (Escape the `?' character as your shell
-g [s] This option excludes or selects the listing of files for the processes whose optional process
group IDentification (PGID) numbers are in the comma-separated set s - e.g., ``123'' or
``123,^456''. (There should be no spaces in the set.)
PGID numbers that begin with `^' (negation) represent exclusions.
Multiple PGID numbers are joined in a single ORed set before participating in AND option
selection. However, PGID exclusions are applied without ORing or ANDing and take effect before
other selection criteria are applied.
The -g option also enables the output display of PGID numbers. When specified without a PGID
set that's all it does.
-i [i] This option selects the listing of files any of whose Internet address matches the address
specified in i. If no address is specified, this option selects the listing of all Internet and
x.25 (HP-UX) network files.
If -i4 or -i6 is specified with no following address, only files of the indicated IP version,
IPv4 or IPv6, are displayed. (An IPv6 specification may be used only if the dialects supports
IPv6, as indicated by ``'' and ``IPv'' in lsof's -h or -? output.) Sequentially
specifying -i4, followed by -i6 is the same as specifying -i, and vice-versa. Specifying -i4,
or -i6 after -i is the same as specifying -i4 or -i6 by itself.
Multiple addresses (up to a limit of 100) may be specified with multiple -i options. (A port
number or service name range is counted as one address.) They are joined in a single ORed set
before participating in AND option selection.
An Internet address is specified in the form (Items in square brackets are optional.):
46 specifies the IP version, IPv4 or IPv6
that applies to the following address.
'6' may be be specified only if the UNIX
dialect supports IPv6. If neither '4' nor
'6' is specified, the following address
applies to all IP versions.
protocol is a protocol name - TCP, UDP
hostname is an Internet host name. Unless a
specific IP version is specified, open
network files associated with host names
of all versions will be selected.
hostaddr is a numeric Internet IPv4 address in
dot form; or an IPv6 numeric address in
colon form, enclosed in brackets, if the
UNIX dialect supports IPv6. When an IP
version is selected, only its numeric
addresses may be specified.
service is an /etc/services name - e.g., smtp -
or a list of them.
port is a port number, or a list of them.
IPv6 options may be used only if the UNIX dialect supports IPv6. To see if the dialect supports
IPv6, run lsof and specify the -h or -? (help) option. If the displayed description of the -i
option contains ``'' and ``IPv'', IPv6 is supported.
IPv4 host names and addresses may not be specified if network file selection is limited to IPv6
with -i 6. IPv6 host names and addresses may not be specified if network file selection is
limited to IPv4 with -i 4. When an open IPv4 network file's address is mapped in an IPv6
address, the open file's type will be IPv6, not IPv4, and its display will be selected by '6',
At least one address component - 4, 6, protocol, ,IR hostname , hostaddr, or service - must be
supplied. The `@' character, leading the host specification, is always required; as is the `:',
leading the port specification. Specify either hostname or hostaddr. Specify either service
name list or port number list. If a service name list is specified, the protocol may also need
to be specified if the TCP, UDP and UDPLITE port numbers for the service name are different.
Use any case - lower or upper - for protocol.
Service names and port numbers may be combined in a list whose entries are separated by commas
and whose numeric range entries are separated by minus signs. There may be no embedded spaces,
and all service names must belong to the specified protocol. Since service names may contain
embedded minus signs, the starting entry of a range can't be a service name; it can be a port
Here are some sample addresses:
-i6 - IPv6 only
TCP:25 - TCP and port 25
@126.96.36.199 - Internet IPv4 host address 188.8.131.52
@[3ffe:1ebc::1]:1234 - Internet IPv6 host address
3ffe:1ebc::1, port 1234
UDP:who - UDP who service port
TCP@lsof.itap:513 - TCP, port 513 and host name lsof.itap
tcp@foo:1-10,smtp,99 - TCP, ports 1 through 10,
service name smtp, port 99, host name foo
tcp@bar:1-smtp - TCP, ports 1 through smtp, host bar
:time - either TCP, UDP or UDPLITE time service port
-k k This option specifies a kernel name list file, k, in place of /vmunix, /mach, etc. This option
is not available under AIX on the IBM RISC/System 6000.
-l This option inhibits the conversion of user ID numbers to login names. It is also useful when
login name lookup is working improperly or slowly.
+|-L [l] This option enables (`+') or disables (`-') the listing of file link counts, where they are
available - e.g., they aren't available for sockets, or most FIFOs and pipes.
When +L is specified without a following number, all link counts will be listed. When -L is
specified (the default), no link counts will be listed.
When +L is followed by a number, only files having a link count less than that number will be
listed. (No number may follow -L.) A specification of the form ``+L1'' will select open files
that have been unlinked. A specification of the form ``+aL1 <file_system>'' will select
unlinked open files on the specified file system.
For other link count comparisons, use field output (-F) and a post-processing script or program.
+|-m m This option specifies an alternate kernel memory file or activates mount table supplement
The option form -m m specifies a kernel memory file, m, in place of /dev/kmem or /dev/mem -
e.g., a crash dump file.
The option form +m requests that a mount supplement file be written to the standard output file.
All other options are silently ignored.
There will be a line in the mount supplement file for each mounted file system, containing the
mounted file system directory, followed by a single space, followed by the device number in
hexadecimal "0x" format - e.g.,
Lsof can use the mount supplement file to get device numbers for file systems when it can't get
them via stat(2) or lstat(2).
The option form +m m identifies m as a mount supplement file.
Note: the +m and +m m options are not available for all supported dialects. Check the output of
lsof's -h or -? options to see if the +m and +m m options are available.
+|-M Enables (+) or disables (-) the reporting of portmapper registrations for local TCP, UDP and
UDPLITE ports. The default reporting mode is set by the lsof builder with the HASPMAPENABLED
#define in the dialect's machine.h header file; lsof is distributed with the HASPMAPENABLED
#define deactivated, so portmapper reporting is disabled by default and must be requested with
+M. Specifying lsof's -h or -? option will report the default mode. Disabling portmapper
registration when it is already disabled or enabling it when already enabled is acceptable.
When portmapper registration reporting is enabled, lsof displays the portmapper registration (if
any) for local TCP, UDP or UDPLITE ports in square brackets immediately following the port
numbers or service names - e.g., ``:1234[name]'' or ``:name''. The registration
information may be a name or number, depending on what the registering program supplied to the
portmapper when it registered the port.
When portmapper registration reporting is enabled, lsof may run a little more slowly or even
become blocked when access to the portmapper becomes congested or stopped. Reverse the
reporting mode to determine if portmapper registration reporting is slowing or blocking lsof.
For purposes of portmapper registration reporting lsof considers a TCP, UDP or UDPLITE port
local if: it is found in the local part of its containing kernel structure; or if it is located
in the foreign part of its containing kernel structure and the local and foreign Internet
addresses are the same; or if it is located in the foreign part of its containing kernel
structure and the foreign Internet address is INADDR_LOOPBACK (127.0.0.1). This rule may make
lsof ignore some foreign ports on machines with multiple interfaces when the foreign Internet
address is on a different interface from the local one.
See the lsof FAQ (The FAQ section gives its location.) for further discussion of portmapper
registration reporting issues.
-n This option inhibits the conversion of network numbers to host names for network files.
Inhibiting conversion may make lsof run faster. It is also useful when host name lookup is not
-N This option selects the listing of NFS files.
-o This option directs lsof to display file offset at all times. It causes the SIZE/OFF output
column title to be changed to OFFSET. Note: on some UNIX dialects lsof can't obtain accurate or
consistent file offset information from its kernel data sources, sometimes just for particular
kinds of files (e.g., socket files.) Consult the lsof FAQ (The FAQ section gives its location.)
for more information.
The -o and -s options are mutually exclusive; they can't both be specified. When neither is
specified, lsof displays whatever value - size or offset - is appropriate and available for the
type of the file.
-o o This option defines the number of decimal digits (o) to be printed after the ``0t'' for a file
offset before the form is switched to ``0x...''. An o value of zero (unlimited) directs lsof to
use the ``0t'' form for all offset output.
This option does NOT direct lsof to display offset at all times; specify -o (without a trailing
number) to do that. This option only specifies the number of digits after ``0t'' in either
mixed size and offset or offset-only output. Thus, for example, to direct lsof to display
offset at all times with a decimal digit count of 10, use:
-o -o 10
The default number of digits allowed after ``0t'' is normally 8, but may have been changed by
the lsof builder. Consult the description of the -o o option in the output of the -h or -?
option to determine the default that is in effect.
-O This option directs lsof to bypass the strategy it uses to avoid being blocked by some kernel
operations - i.e., doing them in forked child processes. See the BLOCKS AND TIMEOUTS and
AVOIDING KERNEL BLOCKS sections for more information on kernel operations that may block lsof.
While use of this option will reduce lsof startup overhead, it may also cause lsof to hang when
the kernel doesn't respond to a function. Use this option cautiously.
-p s This option excludes or selects the listing of files for the processes whose optional process
IDentification (PID) numbers are in the comma-separated set s - e.g., ``123'' or ``123,^456''.
(There should be no spaces in the set.)
PID numbers that begin with `^' (negation) represent exclusions.
Multiple process ID numbers are joined in a single ORed set before participating in AND option
selection. However, PID exclusions are applied without ORing or ANDing and take effect before
other selection criteria are applied.
-P This option inhibits the conversion of port numbers to port names for network files. Inhibiting
the conversion may make lsof run a little faster. It is also useful when port name lookup is
not working properly.
This option puts lsof in repeat mode. There lsof lists open files as selected by other options,
delays t seconds (default fifteen), then repeats the listing, delaying and listing repetitively
until stopped by a condition defined by the prefix to the option.
If the prefix is a `-', repeat mode is endless. Lsof must be terminated with an interrupt or
If the prefix is `+', repeat mode will end the first cycle no open files are listed - and of
course when lsof is stopped with an interrupt or quit signal. When repeat mode ends because no
files are listed, the process exit code will be zero if any open files were ever listed; one, if
none were ever listed.
Lsof marks the end of each listing: if field output is in progress (the -F, option has been
specified), the default marker is `m'; otherwise the default marker is ``========''. The marker
is followed by a NL character.
The optional "m<fmt>" argument specifies a format for the marker line. The <fmt> characters
following `m' are interpreted as a format specification to the strftime(3) function, when both
it and the localtime(3) function are available in the dialect's C library. Consult the
strftime(3) documentation for what may appear in its format specification. Note that when field
output is requested with the -F option, <fmt> cannot contain the NL format, ``%n''. Note also
that when <fmt> contains spaces or other characters that affect the shell's interpretation of
arguments, <fmt> must be quoted appropriately.
Repeat mode reduces lsof startup overhead, so it is more efficient to use this mode than to call
lsof repetitively from a shell script, for example.
To use repeat mode most efficiently, accompany +|-r with specification of other lsof selection
options, so the amount of kernel memory access lsof does will be kept to a minimum. Options
that filter at the process level - e.g., -c, -g, -p, -u - are the most efficient selectors.
Repeat mode is useful when coupled with field output (see the -F, option description) and a
supervising awk or Perl script, or a C program.
-R This option directs lsof to list the Parent Process IDentification number in the PPID column.
-s [p:s] s alone directs lsof to display file size at all times. It causes the SIZE/OFF output column
title to be changed to SIZE. If the file does not have a size, nothing is displayed.
When followed by a protocol name (p), either TCP or UDP, a colon (`:') and a comma-separated
protocol state name list, the option causes open TCP and UDP files to be excluded if their state
name(s) are in the list (s) preceded by a `^'; or included if their name(s) are not preceded by
When an inclusion list is defined, only network files with state names in the list will be
present in the lsof output. Thus, specifying one state name means that only network files with
that lone state name wil be listed.
Case is unimportant in the protocol or state names, but there may be no spaces and the colon
(`:') separating the protocol name (p) and the state name list (s) is required.
If only TCP and UDP files are to be listed, as controlled by the specified exclusions and
inclusions, the -i option must be specified, too. If only a single protocol's files are to be
listed, add its name as an argument to the -i option.
For example, to list only network files with TCP state LISTEN, use:
Or, for example, to list network files with all UDP states except Idle, use:
State names vary with UNIX dialects, so it's not possible to provide a complete list. Some
common TCP state names are: CLOSED, IDLE, BOUND, LISTEN, ESTABLISHED, SYN_SENT, SYN_RCDV,
ESTABLISHED, CLOSE_WAIT, FIN_WAIT1, CLOSING, LAST_ACK, FIN_WAIT_2, and TIME_WAIT. Two common
UDP state names are Unbound and Idle.
See the lsof FAQ (The FAQ section gives its location.) for more information on how to use
protocol state exclusion and inclusion, including examples.
The -o (without a following decimal digit count) and -s option (without a following protocol and
state name list) are mutually exclusive; they can't both be specified. When neither is
specified, lsof displays whatever value - size or offset - is appropriate and available for the
type of file.
Since some types of files don't have true sizes - sockets, FIFOs, pipes, etc. - lsof displays
for their sizes the content amounts in their associated kernel buffers, if possible.
-S [t] This option specifies an optional time-out seconds value for kernel functions - lstat(2),
readlink(2), and stat(2) - that might otherwise deadlock. The minimum for t is two; the
default, fifteen; when no value is specified, the default is used.
See the BLOCKS AND TIMEOUTS section for more information.
-T [t] This option controls the reporting of some TCP/TPI information, also reported by netstat(1),
following the network addresses. In normal output the information appears in parentheses, each
item except TCP or TPI state name identified by a keyword, followed by `=', separated from
others by a single space:
<TCP or TPI state name>
QR=<read queue length>
QS=<send queue length>
SO=<socket options and values>
TF=<TCP flags and values>
WR=<window read length>
WW=<window write length>
Not all values are reported for all UNIX dialects. Items values (when available) are reported
after the item name and '='.
When the field output mode is in effect (See OUTPUT FOR OTHER PROGRAMS.) each item appears as a
field with a `T' leading character.
-T with no following key characters disables TCP/TPI information reporting.
-T with following characters selects the reporting of specific TCP/TPI information:
f selects reporting of socket options,
states and values, and TCP flags and
q selects queue length reporting.
s selects connection state reporting.
w selects window size reporting.
Not all selections are enabled for some UNIX dialects. State may be selected for all dialects
and is reported by default. The -h or -? help output for the -T option will show what
selections may be used with the UNIX dialect.
When -T is used to select information - i.e., it is followed by one or more selection characters
- the displaying of state is disabled by default, and it must be explicitly selected again in
the characters following -T. (In effect, then, the default is equivalent to -Ts.) For example,
if queue lengths and state are desired, use -Tqs.
Socket options, socket states, some socket values, TCP flags and one TCP value may be reported
(when available in the UNIX dialect) in the form of the names that commonly appear after SO_,
so_, SS_, TCP_ and TF_ in the dialect's header files - most often <sys/socket.h>,
<sys/socketvar.h> and <netinet/tcp_var.h>. Consult those header files for the meaning of the
flags, options, states and values.
``SO='' precedes socket options and values; ``SS='', socket states; and ``TF='', TCP flags and
If a flag or option has a value, the value will follow an '=' and the name -- e.g.,
``SO=LINGER=5'', ``SO=QLIM=5'', ``TF=MSS=512''. The following seven values may be reported:
Reported Description (Common Symbol)
KEEPALIVE keep alive time (SO_KEEPALIVE)
LINGER linger time (SO_LINGER)
MSS maximum segment size (TCP_MAXSEG)
PQLEN partial listen queue connections
QLEN established listen queue connections
QLIM established listen queue limit
RCVBUF receive buffer length (SO_RCVBUF)
SNDBUF send buffer length (SO_SNDBUF)
Details on what socket options and values, socket states, and TCP flags and values may be
displayed for particular UNIX dialects may be found in the answer to the ``Why doesn't lsof
report socket options, socket states, and TCP flags and values for my dialect?'' and ``Why
doesn't lsof report the partial listen queue connection count for my dialect?'' questions in
the lsof FAQ (The FAQ section gives its location.)
-t This option specifies that lsof should produce terse output with process identifiers only and no
header - e.g., so that the output may be piped to kill(1). This option selects the -w option.
-u s This option selects the listing of files for the user whose login names or user ID numbers are
in the comma-separated set s - e.g., ``abe'', or ``548,root''. (There should be no spaces in
Multiple login names or user ID numbers are joined in a single ORed set before participating in
AND option selection.
If a login name or user ID is preceded by a `^', it becomes a negation - i.e., files of
processes owned by the login name or user ID will never be listed. A negated login name or user
ID selection is neither ANDed nor ORed with other selections; it is applied before all other
selections and absolutely excludes the listing of the files of the process. For example, to
direct lsof to exclude the listing of files belonging to root processes, specify ``-u^root'' or
-U This option selects the listing of UNIX domain socket files.
-v This option selects the listing of lsof version information, including: revision number; when
the lsof binary was constructed; who constructed the binary and where; the name of the compiler
used to construct the lsof binary; the version number of the compiler when readily available;
the compiler and loader flags used to construct the lsof binary; and system information,
typically the output of uname's -a option.
-V This option directs lsof to indicate the items it was asked to list and failed to find - command
names, file names, Internet addresses or files, login names, NFS files, PIDs, PGIDs, and UIDs.
When other options are ANDed to search options, or compile-time options restrict the listing of
some files, lsof may not report that it failed to find a search item when an ANDed option or
compile-time option prevents the listing of the open file containing the located search item.
For example, ``lsof -V -iTCP@foobar -a -d 999'' may not report a failure to locate open files at
``TCP@foobar'' and may not list any, if none have a file descriptor number of 999. A similar
situation arises when HASSECURITY and HASNOSOCKSECURITY are defined at compile time and they
prevent the listing of open files.
+|-w Enables (+) or disables (-) the suppression of warning messages.
The lsof builder may choose to have warning messages disabled or enabled by default. The
default warning message state is indicated in the output of the -h or -? option. Disabling
warning messages when they are already disabled or enabling them when already enabled is
The -t option selects the -w option.
-x [fl] This option may accompany the +d and +D options to direct their processing to cross over
symbolic links and|or file system mount points encountered when scanning the directory (+d) or
directory tree (+D).
If -x is specified by itself without a following parameter, cross-over processing of both
symbolic links and file system mount points is enabled. Note that when -x is specified without
a parameter, the next argument must begin with '-' or '+'.
The optional 'f' parameter enables file system mount point cross-over processing; 'l', symbolic
link cross-over processing.
The -x option may not be supplied without also supplying a +d or +D option.
-X This is a dialect-specific option.
This IBM AIX RISC/System 6000 option requests the reporting of executed text file and shared
WARNING: because this option uses the kernel readx() function, its use on a busy AIX system
might cause an application process to hang so completely that it can neither be killed nor
stopped. I have never seen this happen or had a report of its happening, but I think there is a
remote possibility it could happen.
By default use of readx() is disabled. On AIX 5L and above lsof may need setuid-root permission
to perform the actions this option requests.
The lsof builder may specify that the -X option be restricted to processes whose real UID is
root. If that has been done, the -X option will not appear in the -h or -? help output unless
the real UID of the lsof process is root. The default lsof distribution allows any UID to
specify -X, so by default it will appear in the help output.
When AIX readx() use is disabled, lsof may not be able to report information for all text and
loader file references, but it may also avoid exacerbating an AIX kernel directory search kernel
error, known as the Stale Segment ID bug.
The readx() function, used by lsof or any other program to access some sections of kernel
virtual memory, can trigger the Stale Segment ID bug. It can cause the kernel's dir_search()
function to believe erroneously that part of an in-memory copy of a file system directory has
been zeroed. Another application process, distinct from lsof, asking the kernel to search the
directory - e.g., by using open(2) - can cause dir_search() to loop forever, thus hanging the
Consult the lsof FAQ (The FAQ section gives its location.) and the 00README file of the lsof
distribution for a more complete description of the Stale Segment ID bug, its APAR, and methods
for defining readx() use when compiling lsof.
This Linux option requests that lsof skip the reporting of information on all open TCP, UDP and
UDPLITE IPv4 and IPv6 files.
This Linux option is most useful when the system has an extremely large number of open TCP, UDP
and UDPLITE files, the processing of whose information in the /proc/net/tcp* and /proc/net/udp*
files would take lsof a long time, and whose reporting is not of interest.
Use this option with care and only when you are sure that the information you want lsof to
display isn't associated with open TCP, UDP or UDPLITE socket files.
Solaris 10 and above:
This Solaris 10 and above option requests the reporting of cached paths for files that have been
deleted - i.e., removed with rm(1) or unlink(2).
The cached path is followed by the string `` (deleted)'' to indicate that the path by which the
file was opened has been deleted.
Because intervening changes made to the path - i.e., renames with mv(1) or rename(2) - are not
recorded in the cached path, what lsof reports is only the path by which the file was opened,
not its possibly different final path.
-z [z] specifies how Solaris 10 and higher zone information is to be handled.
Without a following argument - e.g., NO z - the option specifies that zone names are to be
listed in the ZONE output column.
The -z option may be followed by a zone name, z. That causes lsof to list only open files for
processes in that zone. Multiple -z z option and argument pairs may be specified to form a list
of named zones. Any open file of any process in any of the zones will be listed, subject to
other conditions specified by other options and arguments.
-Z [Z] specifies how SELinux security contexts are to be handled. This option and 'Z' field output
character support are inhibited when SELinux is disabled in the running Linux kernel. See
OUTPUT FOR OTHER PROGRAMS for more information on the 'Z' field output character.
Without a following argument - e.g., NO Z - the option specifies that security contexts are to
be listed in the SECURITY-CONTEXT output column.
The -Z option may be followed by a wildcard security context name, Z. That causes lsof to list
only open files for processes in that security context. Multiple -Z Z option and argument pairs
may be specified to form a list of security contexts. Any open file of any process in any of
the security contexts will be listed, subject to other conditions specified by other options and
arguments. Note that Z can be A:B:C or *:B:C or A:B:* or *:*:C to match against the A:B:C
-- The double minus sign option is a marker that signals the end of the keyed options. It may be
used, for example, when the first file name begins with a minus sign. It may also be used when
the absence of a value for the last keyed option must be signified by the presence of a minus
sign in the following option and before the start of the file names.
names These are path names of specific files to list. Symbolic links are resolved before use. The
first name may be separated from the preceding options with the ``--'' option.
If a name is the mounted-on directory of a file system or the device of the file system, lsof
will list all the files open on the file system. To be considered a file system, the name must
match a mounted-on directory name in mount(8) output, or match the name of a block device
associated with a mounted-on directory name. The +|-f option may be used to force lsof to
consider a name a file system identifier (+f) or a simple file (-f).
If name is a path to a directory that is not the mounted-on directory name of a file system, it
is treated just as a regular file is treated - i.e., its listing is restricted to processes that
have it open as a file or as a process-specific directory, such as the root or current working
directory. To request that lsof look for open files inside a directory name, use the +d s and
+D D options.
If a name is the base name of a family of multiplexed files - e. g, AIX's /dev/pt[cs] - lsof
will list all the associated multiplexed files on the device that are open - e.g.,
/dev/pt[cs]/1, /dev/pt[cs]/2, etc.
If a name is a UNIX domain socket name, lsof will usually search for it by the characters of the
name alone - exactly as it is specified and is recorded in the kernel socket structure. (See
the next paragraph for an exception to that rule for Linux.) Specifying a relative path - e.g.,
./file - in place of the file's absolute path - e.g., /tmp/file - won't work because lsof must
match the characters you specify with what it finds in the kernel UNIX domain socket structures.
If a name is a Linux UNIX domain socket name, in one case lsof is able to search for it by its
device and inode number, allowing name to be a relative path. The case requires that the
absolute path -- i.e., one beginning with a slash ('/') be used by the process that created the
socket, and hence be stored in the /proc/net/unix file; and it requires that lsof be able to
obtain the device and node numbers of both the absolute path in /proc/net/unix and name via
successful stat(2) system calls. When those conditions are met, lsof will be able to search for
the UNIX domain socket when some path to it is is specified in name. Thus, for example, if the
path is /dev/log, and an lsof search is initiated when the working directory is /dev, then name
could be ./log.
If a name is none of the above, lsof will list any open files whose device and inode match that
of the specified path name.
If you have also specified the -b option, the only names you may safely specify are file systems
for which your mount table supplies alternate device numbers. See the AVOIDING KERNEL BLOCKS
and ALTERNATE DEVICE NUMBERS sections for more information.
Multiple file names are joined in a single ORed set before participating in AND option