//po4a: entry man manual
////
Copyright 2021 Red Hat, Inc.

This file may be copied under the terms of the GNU Public License.
////
= lsfd(1)
:doctype: manpage
:man manual: User Commands
:man source: util-linux {release-version}
:page-layout: base
:command: lsfd
:colon: :

== NAME

lsfd - list file descriptors

== SYNOPSIS

*lsfd* [option]

== DESCRIPTION

*lsfd* is intended to be a modern replacement for *lsof*(8) on Linux systems.
Unlike *lsof*, *lsfd* is specialized to Linux kernel; it supports Linux
specific features like namespaces with simpler code. *lsfd* is not a
drop-in replacement for *lsof*; they are different in the command line
interface and output formats.

The default output is subject to change. So whenever possible, you should avoid using
default outputs in your scripts. Always explicitly define expected columns by using
*--output* _columns-list_ in environments where a stable output is required.

*lsfd* uses Libsmartcols for output formatting and filtering. See the description of *--output*
option for customizing the output format, and *--filter* option for filtering. Use *lsfd --list-columns*
to get a list of all available columns.

== OPTIONS

*-l*, *--threads*::
List in threads level.

*-J*, *--json*::
Use JSON output format.

*-n*, *--noheadings*::
Don't print headings.

*-o*, *--output* _list_::
Specify which output columns to print. See the *OUTPUT COLUMNS*
section for details of available columns.
+
The default list of columns may be extended if _list_ is specified in
the format +_list_ (e.g., *lsfd -o +DELETED*).

*-r*, *--raw*::
Use raw output format.

*--notruncate*::
Don't truncate text in columns.

*-p*, *--pid* _pids_::
Collect information only for specified processes.
_pids_ is a list of pids. A comma or whitespaces can be used as separators.
You can use this option with *pidof*(1). See *FILTER EXAMPLES*.
+
Both *-Q* option with an expression including PID, e.g. -Q (PID == 1),
and *-p* option, e.g. -p 1, may print the same output but using *-p*
option is much more efficient because *-p* option works at a much earlier
stage of processing than the *-Q* option.

*-i*[4|6], *--inet*[=4|=6]::
List only IPv4 sockets and/or IPv6 sockets.

*-Q*, *--filter* _expr_::
Print only the files matching the condition represented by the _expr_.
See also *scols-filter*(5) and *FILTER EXAMPLES*.

*-C*, *--counter* __label__:__filter_expr__::
Define a custom counter used in *--summary* output. *lsfd* makes a
counter named _label_. During collect information, *lsfd* counts files
matching _filter_expr_, and stores the counted number to the
counter named _label_. *lsfd* applies filters defined with *--filter*
options before counting; files excluded by the filters are not counted.
+
See *scols-filter*(5) about _filter_expr_.
_label_ should not include `{` nor `:`. You can define multiple
counters by specifying this option multiple times.
+
See also *COUNTER EXAMPLES*.

*--summary*[=_when_]::
This option controls summary lines output. The optional argument _when_
can be *only*, *append* or *never*. If the _when_ argument is omitted,
it defaults to *only*.
+
The summary reports counters. A counter consists of a label and an
integer value.  *--counter* is the option for defining a counter.  If
a user defines no counter, *lsfd* uses the definitions of pre-defined
built-in counters (default counters) to make the summary output.
+
CAUTION{colon} Using *--summary* and *--json* may make the output broken. Only combining *--summary*=*only* and *--json* is valid.
//TRANSLATORS: Keep {colon} untranslated.

*--debug-filter*::
Dump the internal data structure for the filter and exit. This is useful
only for *lsfd* developers.

*--dump-counters*::
Dump the definition of counters used in *--summary* output.

*-H*, *--list-columns*::
List available columns that you can specify at *--output* option.

include::man-common/help-version.adoc[]

== OUTPUT COLUMNS

Each column has a type. Types are surround by < and >.

//TRANSLATORS: Keep {colon} untranslated.
CAUTION{colon} The names and types of columns are not stable yet.
They may be changed in the future releases.

AINODECLASS <``string``>::
Class of anonymous inode.

ASSOC <``string``>::
Association between file and process.

BLKDRV <``string``>::
Block device driver name resolved by `/proc/devices`.

BPF-MAP.ID <``number``>::
Bpf map ID.

BPF-MAP.TYPE <``string``>::
Decoded name of bpf map type.

BPF-MAP.TYPE.RAW <``number``>::
Bpf map type (raw).

BPF.NAME <``string``>::
Bpf object name.

BPF-PROG.ID <``number``>::
Bpf program ID.

BPF-PROG.TYPE <``string``>::
Decoded name of bpf program type.

BPF-PROG.TYPE.RAW <``number``>::
Bpf program type (raw).

CHRDRV <``string``>::
Character device driver name resolved by `/proc/devices`.

COMMAND <``string``>::
Command of the process opening the file.

DELETED <``boolean``>::
Reachability from the file system.

DEV <``string``>::
ID of the device containing the file.

DEVTYPE <``string``>::
Device type (`blk`, `char`, or `nodev`).

ENDPOINT <``string``>::
IPC endpoints information communicated with the fd.
+
*lsfd* collects endpoints within the processes that
*lsfd* scans; *lsfd* may miss some endpoints
if you limits the processes with *-p* option.
+
The format of the column depends on the object associated
with the fd:

FIFO type:::
mqueue type:::
ptmx and pts sources:::
_PID_,_COMMAND_,_ASSOC_[-r][-w]
+
The last characters ([-r][-w]) represents the read and/or
write mode of the endpoint.

eventfd type:::
_PID_,_COMMAND_,_ASSOC_

UNIX-STREAM:::
_PID_,_COMMAND_,_ASSOC_[-r?][-w?]
+
About the last characters ([-r?][-w?]), see the description
of _SOCK.SHUTDOWN_.

EVENTFD.ID <``number``>::
Eventfd ID.

EVENTPOLL.TFDS <``string``>::
File descriptors targeted by the eventpoll file.

FD <``number``>::
File descriptor for the file.

FLAGS <``string``>::
Flags specified when opening the file.

FUID <``number``>::
User ID number of the file's owner.

INET.LADDR <``string``>::
Local IP address.

INET.RADDR <``string``>::
Remote IP address.

INET6.LADDR <``string``>::
Local IP6 address.

INET6.RADDR <``string``>::
Remote IP6 address.

INODE <``number``>::
Inode number.

INOTIFY.INODES <``string``>::
Cooked version of INOTIFY.INODES.RAW.
The format of the element is
_inode-number_,_source-of-inode_.

INOTIFY.INODES.RAW <``string``>::
List of monitoring inodes. The format of the element
is _inode-number_``,``_device-major_``:``_device-minor_.

KNAME <``string``>::
//
// It seems that the manpage backend of asciidoctor has limitations
// about emitting text with nested face specifications like:
//
//   `_u_` p
//
// Not only u but also p is decorated with underline.
//
Raw file name extracted from
from ``/proc/``_pid_``/fd/``_fd_ or ``/proc/``_pid_``/map_files/``_region_.

KTHREAD <``boolean``>::
Whether the process is a kernel thread or not.

MAJ:MIN <``string``>::
Device ID for special, or ID of device containing file.

MAPLEN <``number``>::
Length of file mapping (in page).

MISCDEV <``string``>::
Misc character device name resolved by `/proc/misc`.

MNTID <``number``>::
Mount ID.

MODE <``string``>::
Access mode (rwx).

NAME <``string``>::
Cooked version of KNAME. It is mostly same as KNAME.
+
Some files have special formats and information sources:
+
bpf-map:::
id=_BPF-MAP.ID_ type=_BPF-MAP.TYPE_[ name=_BPF.NAME_]
+
bpf-prog:::
id=_BPF-PROG.ID_ type=_BPF-PROG.TYPE_[ name=_BPF.NAME_]
+
eventpoll:::
tfds=_EVENTPOLL.TFDS_
+
eventfd:::
id=_EVENTFD.ID_
+
inotify:::
inodes=_INOTIFY.INODES_
+
misc:tun:::
iface=_TUN.IFACE_
+
NETLINK:::
protocol=_NETLINK.PROTOCOL_[ lport=_NETLINK.LPORT_[ group=_NETLINK.GROUPS_]]
+
PACKET:::
type=_SOCK.TYPE_[ protocol=_PACKET.PROTOCOL_][ iface=_PACKET.IFACE_]
+
pidfd:::
pid=_TARGET-PID_ comm=_TARGET-COMMAND_ nspid=_TARGET-NSPIDS_
+
*lsfd* extracts _TARGET-PID_ and _TARGET-NSPIDS_ from
``/proc/``_pid_``/fdinfo/``_fd_.
+
PING:::
state=_SOCK.STATE_[ id=_PING.ID_][ laddr=_INET.LADDR_ [ raddr=_INET.RADDR_]]
+
PINGv6:::
state=_SOCK.STATE_[ id=_PING.ID_][ laddr=_INET6.LADDR_ [ raddr=_INET6.RADDR_]]
+
ptmx:::
tty-index=_PTMX.TTY-INDEX_
+
*lsfd* extracts _PTMX.TTY-INDEX_ from
``/proc/``_pid_``/fdinfo/``_fd_.
+
RAW:::
state=_SOCK.STATE_[ protocol=_RAW.PROTOCOL_ [ laddr=_INET.LADDR_ [ raddr=_INET.RADDR_]]]
+
RAWv6:::
state=_SOCK.STATE_[ protocol=_RAW.PROTOCOL_ [ laddr=_INET6.LADDR_ [ raddr=_INET6.RADDR_]]]
+
signalfd:::
mask=_SIGNALFD.MASK_
+
TCP:::
TCPv6:::
state=_SOCK.STATE_[ laddr=_TCP.LADDR_ [ raddr=_TCP.RADDR_]]
+
timerfd:::
clockid=_TIMERFD.CLOCKID_[ remaining=_TIMERFD.REMAINING_ [ interval=_TIMERFD.INTERVAL_]]
+
UDP:::
UDPv6:::
state=_SOCK.STATE_[ laddr=_UDP.LADDR_ [ raddr=_UDP.RADDR_]]
+
*lsfd* hides ``raddr=`` if _UDP.RADDR_ is ``0.0.0.0`` and _UDP.RPORT_ is 0.
+
UDP-LITE:::
UDPLITEv6:::
state=_SOCK.STATE_[ laddr=_UDPLITE.LADDR_ [ raddr=_UDPLITE.RADDR_]]
+
UNIX-STREAM:::
state=_SOCK.STATE_[ path=_UNIX.PATH_]
+
UNIX:::
state=_SOCK.STATE_[ path=_UNIX.PATH_] type=_SOCK.TYPE_

____
Note that `(deleted)` markers are removed from this column.
Refer to _KNAME_, _DELETED_, or _XMODE_ to know the
readability of the file from the file system.
____

NETLINK.GROUPS <``number``>::
Netlink multicast groups.

NETLINK.LPORT <``number``>::
Netlink local port id.

NETLINK.PROTOCOL <``string``>::
Netlink protocol.

NLINK <``number``>::
Link count.

NS.NAME <``string``>::
Name (_NS.TYPE_:[_INODE_]) of the namespace specified with the file.

NS.TYPE <``string``>::
Type of the namespace specified with the file.
The type is `mnt`, `cgroup`, `uts`, `ipc`, `user`, `pid`, `net`,
`time`, or `unknown`.

OWNER <``string``>::
Owner of the file.

PACKET.IFACE <``string``>::
Interface name associated with the packet socket.

PACKET.PROTOCOL <``string``>::
L3 protocol associated with the packet socket.

PARTITION <``string``>::
Block device name resolved by `/proc/partition`.

PID <``number``>::
PID of the process opening the file.

PIDFD.COMM <``string``>::
Command of the process targeted by the pidfd.

PIDFD.NSPID <``string``>::
Value of NSpid field in ``/proc/``_pid_``/fdinfo/``_fd_ of the pidfd.
+
Quoted from kernel/fork.c of Linux source tree:
+
____
If pid namespaces are supported then this function will also print
the pid of a given pidfd refers to for all descendant pid namespaces
starting from the current pid namespace of the instance, i.e. the
Pid field and the first entry in the NSpid field will be identical.

Note that this differs from the Pid and NSpid fields in
/proc/<pid>/status where Pid and NSpid are always shown relative to
the pid namespace of the procfs instance.
____

PIDFD.PID <``number``>::
PID of the process targeted by the pidfd.

PING.ID <`number`>::
ICMP echo request id used on the PING socket.

POS <``number``>::
File position.

RAW.PROTOCOL <``number``>::
Protocol number of the raw socket.

RDEV <``string``>::
Device ID (if special file).

SIGNALFD.MASK <``string``>::
Masked signals.

SIZE <``number``>::
File size.

SOCK.LISTENING <``boolean``>::
Listening socket.

SOCK.NETS <``number``>::
Inode identifying network namespace where the socket belongs to.

SOCK.PROTONAME <``string``>::
Protocol name.

SOCK.SHUTDOWN <``string``>::
Shutdown state of socket.
+
[-r?]:::
If the first character is _r_, the receptions are allowed.
If it is _-_, the receptions are disallowed.
If it is _?_, the state is unknown.
+
[-w?]:::
If the second character is _w_, the transmissions are allowed.
If it is _-_, the transmissions are disallowed.
If it is _?_, the state is unknown.

SOCK.STATE <``string``>::
State of socket.

SOCK.TYPE <``string``>::
Type of socket. Here type means the second parameter of
socket system call:
+
* stream
* dgram
* raw
* rdm
* seqpacket
* dccp
* packet

SOURCE <``string``>::
File system, partition, or device containing the file.

STTYPE <``string``>::
Raw file types returned from *stat*(2): BLK, CHR, DIR, FIFO, LINK, REG, SOCK, or UNKN.

TCP.LADDR <``string``>::
Local L3 (_INET.LADDR_ or _INET6.LADDR_) address and local TCP port.

TCP.LPORT <``number``>::
Local TCP port.

TCP.RADDR <``string``>::
Remote L3 (_INET.RADDR_ or _INET6.RADDR_) address and remote TCP port.

TCP.RPORT <``number``>::
Remote TCP port.

TID <``number``>::
Thread ID of the process opening the file.

TIMERFD.CLOCKID <``string``>::
Clockid.

TIMERFD.INTERVAL <``number``>::
Interval.

TIMERFD.REMAINING <``number``>::
Remaining time.

PTMX.TTY-INDEX <``number``>::
TTY index of the counterpart.

TUN.IFACE <``string``>::
Network interface behind the tun device.

TYPE <``string``>::
Cooked version of _STTYPE_. It is same as _STTYPE_ with exceptions.
For _SOCK_, print the value for _SOCK.PROTONAME_.
For _UNKN_, print the value for _AINODECLASS_ if _SOURCE_ is `anon_inodefs`.

UDP.LADDR <``string``>::
Local IP address and local UDP port.

UDP.LPORT <``number``>::
Local UDP port.

UDP.RADDR <``string``>::
Remote IP address and remote UDP port.

UDP.RPORT <``number``>::
Remote UDP port.

UDPLITE.LADDR <``string``>::
Local IP address and local UDPLite port.

UDPLITE.LPORT <``number``>::
Local UDP port.

UDPLITE.RADDR <``string``>::
Remote IP address and remote UDPLite port.

UDPLITE.RPORT <``number``>::
Remote UDP port.

UID <``number``>::
User ID number.

UNIX.PATH <``string``>::
Filesystem pathname for UNIX domain socket.

USER <``string``>::
User of the process.

XMODE <``string``>::
Extended version of _MODE_. This column may grow; new letters may be
appended to _XMODE_ when *lsfd* supports a new state of file descriptors
and/or memory mappings.
+
[-r]:::
opened of mapped for reading. This is also in _MODE_.
+
[-w]:::
opened of mapped for writing. This is also in _MODE_.
+
[-x]:::
mapped for executing the code. This is also in _MODE_.
+
[-D]:::
deleted from  the file system. See also _DELETED_.
+
[-Ll]:::
locked or leased. _l_ represents a read, a shared lock or a read lease.
_L_ represents a write or an exclusive lock or a write lease. If both
read/shared and write/exclusive locks or leases are taken by a file
descriptor, _L_ is used as the flag.
+
[-m]:::
Multiplexed. If the file descriptor is targeted by a eventpoll file
or classical system calls for multiplexing (select, pselect, poll, and
ppoll), this bit flag is set. Note that if an invocation of the
classical system calls is interrupted, *lsfd* may fail to mark _m_
on the file descriptors monitored by the invocation.
See *restart_syscall*(2).

== FILTER EXAMPLES

*lsfd* has few options for filtering. In most of cases, what you should
know is *-Q* (or *--filter*) option.  Combined with *-o* (or
*--output*) option, you can customize the output as you want.

//TRANSLATORS: In the following messages, don't forget to add whitespace at the end!
List files associated with PID 1 and PID 2 processes: ::
....
# lsfd -Q '(PID == 1) or (PID == 2)'
....

Do the same in an alternative way: ::
....
# lsfd -Q '(PID == 1) || (PID == 2)'
....

Do the same in a more efficient way: ::
....
# lsfd --pid 1,2
....

Whitescapes can be used instead of a comma: ::
....
# lsfd --pid '1 2'
....

Utilize *pidof*(1) for list the files associated with "firefox": ::
....
# lsfd --pid "$(pidof firefox)"
....

List the 1st file descriptor opened by PID 1 process: ::
....
# lsfd -Q '(PID == 1) and (FD == 1)'
....

Do the same in an alternative way: ::
....
# lsfd -Q '(PID == 1) && (FD == 1)'
....

List all running executables: ::
....
# lsfd -Q 'ASSOC == "exe"'
....

Do the same in an alternative way: ::
....
# lsfd -Q 'ASSOC eq "exe"'
....

Do the same but print only file names: ::
....
# lsfd -o NAME -Q 'ASSOC eq "exe"' | sort -u
....

List deleted files associated to processes: ::
....
# lsfd -Q 'DELETED'
....

List non-regular files: ::
....
# lsfd -Q 'TYPE != "REG"'
....

List block devices: ::
....
# lsfd -Q 'DEVTYPE == "blk"'
....

Do the same with TYPE column: ::
....
# lsfd -Q 'TYPE == "BLK"'
....

List files including "dconf" directory in their names: ::
....
# lsfd -Q 'NAME =~ ".\*/dconf/.*"'
....

List files opened in a QEMU virtual machine: ::
....
# lsfd -Q '(COMMAND =~ ".\*qemu.*") and (FD >= 0)'
....

List timerfd files expired within 0.5 seconds: ::
....
# lsfd -Q '(TIMERFD.remaining < 0.5) and (TIMERFD.remaining > 0.0)'
....

== COUNTER EXAMPLES

Report the numbers of netlink socket descriptors and unix socket descriptors: ::
....
# lsfd --summary=only \
	-C 'netlink sockets':'(NAME =~ "NETLINK:.*")' \
	-C 'unix sockets':'(NAME =~ "UNIX:.*")'
VALUE COUNTER
   57 netlink sockets
 1552 unix sockets
....

Do the same but print in JSON format: ::
....
# lsfd --summary=only --json \
	-C 'netlink sockets':'(NAME =~ "NETLINK:.*")' \
	-C 'unix sockets':'(NAME =~ "UNIX:.*")'
{
   "lsfd-summary": [
      {
	 "value": 15,
	 "counter": "netlink sockets"
      },{
	 "value": 798,
	 "counter": "unix sockets"
      }
   ]
}
....


== HISTORY

The *lsfd* command is part of the util-linux package since v2.38.

== AUTHORS

mailto:yamato@redhat.com[Masatake YAMATO],
mailto:kzak@redhat.com[Karel Zak]

== SEE ALSO
*bpftool*(8)
*bps*(8)
*lslocks*(8)
*lsof*(8)
*pidof*(1)
*proc*(5)
*scols-filter*(5)
*socket*(2)
*ss*(8)
*stat*(2)

include::man-common/bugreports.adoc[]

include::man-common/footer.adoc[]

ifdef::translation[]
include::man-common/translation.adoc[]
endif::[]
