lsfd(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OUTPUT COLUMNS | FILTER EXPRESSION | FILTER EXAMPLES | COUNTER EXAMPLES | HISTORY | AUTHORS | SEE ALSO | REPORTING BUGS | AVAILABILITY

LSFD(1)                       User Commands                      LSFD(1)

NAME         top

       lsfd - list file descriptors

SYNOPSIS         top

       lsfd [option]

DESCRIPTION         top

       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 --help to get
       a list of all available columns.

OPTIONS         top

       -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 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 FILTER EXPRESSION 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: Using --summary and --json may make the output
           broken. Only combining --summary=only and --json is valid.

       --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, --help
           Display help text and exit.

       -V, --version
           Print version and exit.

OUTPUT COLUMNS         top

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

       CAUTION: 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.

       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
               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

       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>
           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:

           eventpoll
               tfds=EVENTPOLL.TFDS

           eventfd
               id=EVENTFD.ID

           inotify
               inodes=INOTIFY.INODES

           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]]

           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

       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.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.

       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.

FILTER EXPRESSION         top

       lsfd evaluates the expression passed to --filter option every
       time before printing a file line. lsfd prints the line only if
       the result of evaluation is true.

       An expression consists of column names, literals and, operators
       like: DELETED, (PID == 1), (NAME == "/etc/passwd"), (PID == 1) &&
       DELETED. DELETED, PID, and NAME are column names in the example.
       1 and "/etc/passwd" are literals. == and && are operators.

       Before evaluation, lsfd substitutes column names in the given
       expression with actual column values in the line. There are three
       different data types: boolean, string, and number. For columns
       with a boolean type, the value can be stand-alone. For string and
       number values, the value must be an operand of an operator, for
       example, (PID == 1). See OUTPUT COLUMNS about the types of
       columns.

       Literal is for representing a value directly. See BOOLLIT,
       STRLIT, and NUMLIT. Different data types have different literal
       syntax.

       An operator works with one or two operand(s). An operator has an
       expectation about the data type(s) of its operands. Giving an
       unexpected data type to an operator causes a syntax error.

       Operators taking two operands are and, or, eq, ne, le, lt, ge,
       gt, =~, !~. Alphabetically named operators have C-language
       flavored aliases: &&, ||, ==, !=, <, ⇐, >=, and >.

       ! is the only operator that takes one operand.

       eq, ne, and their aliases expect operands have the same data
       type. Applying these operators return a boolean.

       and, or, not and their aliases expect operands have boolean data
       type. Applying these operators return a boolean.

       lt, le, gt, ge, and their aliases expect operands have number
       data types. Applying these operators return a boolean.

       =~ is for regular expression matching; if a string at the right
       side matches a regular expression at the left side, the result is
       true. The right side operand must be a string literal. See STRLIT
       about the syntax.

       !~ is a short-hand version of not (STR =~ PAT); it inverts the
       result of =~.

   Limitations
       The current implementation does not define precedences within
       operators. Use ( and ) explicitly for grouping the
       sub-expressions if your expression uses more than two operators.

       About number typed values, the filter engine supports only
       non-negative integers, and non-negative floating point numbers.

   Semi-formal syntax
       EXPR
           BOOLEXP

       BOOLEXP0
           COLUMN <boolean> | BOOLLIT | ( BOOLEXP )

       BOOLEXP
           BOOLEXP0 | BOOLOP1 | BOOLOP2 | BOOLOP2BL | BOOLOP2CMP |
           BOOLOP2REG

       COLUMN
           [_A-Za-z][-_:A-Za-z0-9]*

       BOOLOP1
           ! BOOLEXP0 | not BOOLEXP0

       STREXP
           COLUMN <string> | STRLIT

       NUMEXP
           COLUMN <number> | NUMLIT

       BOOLLIT
           true | false

       CHARS
           ( [^\] | \\ | \' | \" )*

       STRLIT
           ' CHARS ' | " CHARS "

       NUMLIT
           INTLIT | FNUMLIT

       INTLIT
           [1-9][0-9]* | 0

       FNUMLIT
           INTLIT . [0-9][0-9]*

       BOOLOP2
           STREXP OP2 STREXP | NUMEXP OP2 NUMEXP | BOOLEXP0 OP2 BOOLEXP0

       OP2
           == | eq | != | ne

       BOOLOP2BL
           BOOLEXP0 OP2BL BOOLEXP0

       OP2BL
           && | and |  || | or

       BOOLOP2CMP
           NUMEXP OP2CMP NUMEXP

       OP2CMP
           < | lt | <= | le | > | gt | >= | ge

       BOOLOP2REG
           STREXP OP2REG STRLIT

       OP2REG
           =~ | !~

FILTER EXAMPLES         top

       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.

       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)'

       Hide files associated to kernel threads:

           # lsfd -Q '!KTHREAD'

       List timerfd files expired within 0.5 seconds:

           # lsfd -Q '(TIMERFD.remaining < 0.5) and (TIMERFD.remaining > 0.0)'

COUNTER EXAMPLES         top

       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         top

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

AUTHORS         top

       Masatake YAMATO <yamato@redhat.com>, Karel Zak <kzak@redhat.com>

SEE ALSO         top

       lsof(8) pidof(1) proc(5) socket(2) stat(2)

REPORTING BUGS         top

       For bug reports, use the issue tracker at
       https://github.com/util-linux/util-linux/issues.

AVAILABILITY         top

       The lsfd command is part of the util-linux package which can be
       downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>. This page
       is part of the util-linux (a random collection of Linux
       utilities) project. Information about the project can be found at
       ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have
       a bug report for this manual page, send it to
       util-linux@vger.kernel.org. This page was obtained from the
       project's upstream Git repository
       ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
       2023-06-23. (At that time, the date of the most recent commit
       that was found in the repository was 2023-06-22.) If you discover
       any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page,
       or you have corrections or improvements to the information in
       this COLOPHON (which is not part of the original manual page),
       send a mail to man-pages@man7.org

util-linux 2.39.268-ae62d      2023-06-22                        LSFD(1)