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//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: :
lsfd - list file descriptors
*lsfd* [option]
*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.
*lsfd* uses Libsmartcols for output formatting and filtering. See the description of *--output*
option for customizing the output format, and *--filter* option for filtering.
*-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.
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.
*-Q*, *--filter* _expr_::
Print only the files matching the condition represented by the _expr_.
*-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.
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.
Dump the internal data structure for the filter and exit. This is useful
only for *lsfd* developers.
Dump the definition of counters used in *--summary* output.
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.
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.
The format of the column depends on the object associated
with the fd:
FIFO type::: _PID_,_COMMAND_,_ASSOC_[-r][-w]
The last characters ([-r][-w]) represents the read and/or
write mode of the endpoint.
*lsfd* collects endpoints within the processes that
*lsfd* scans; *lsfd* may miss some endpoints
if you limits the processes with *-p* option.
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.
INODE <__number__>::
Inode number.
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__>::
Name of the file.
NLINK <__number__>::
Link count.
OWNER <__string__>::
Owner of the file.
PARTITION <__string__>::
Block device name resolved by _/proc/partition_.
PID <__number__>::
PID of the process opening the file.
POS <__number__>::
File position.
PROTONAME <__string__>::
Protocol name.
RDEV <__string__>::
Device ID (if special file).
SIZE <__number__>::
File size.
SOURCE <__string__>::
File system, partition, or device containing the file.
TID <__number__>::
Thread ID of the process opening the file.
TYPE <__string__>::
File type.
UID <__number__>::
User ID number.
USER <__string__>::
User of the process.
*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 the "OUTPUT COLUMNS" about the types of
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 _bool_ 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
_!~_ 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.
=== Semi-formal syntax
//TRANSLATORS: In the following messages, translate only the <__variables__>.
BOOLEXP0 :: COLUMN <__boolean__> | BOOLLIT | _(_ BOOLEXP _)_
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 :: [1-9][0-9]* | _0_
OP2 :: _==_ | _eq_ | _!=_ | _ne_
OP2BL :: _&&_ | _and_ | _||_ | _or_
OP2CMP :: _<_ | _lt_ | _\<=_ | _le_ | _>_ | _gt_ | _>=_ | _ge_
OP2REG :: _=~_ | _!~_
*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)'
Hide files associated to kernel threads: ::
# lsfd -Q '!KTHREAD'
Report the numbers of netlink socket descriptors and unix socket descriptors: ::
# lsfd --summary=only \
-C 'netlink sockets':'(NAME =~ "NETLINK:.*")' \
-C 'unix sockets':'(NAME =~ "UNIX:.*")'
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"
The *lsfd* command is part of the util-linux package since v2.38.
== AUTHORS[Masatake YAMATO],[Karel Zak]