Provided by: util-linux-extra_2.38-4ubuntu1_amd64 
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.
lsfd uses Libsmartcols for output formatting and filtering. See the description of
--output option for customizing the output format, and --filter option for filtering.
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.
-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
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.
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).
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.
FILTER EXPRESSION
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 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 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 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.
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
[1-9][0-9]* | 0
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
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'
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
Masatake YAMATO <yamato@redhat.com>, Karel Zak <kzak@redhat.com>
SEE ALSO
lsof(8) pidof(1) proc(5)
REPORTING BUGS
For bug reports, use the issue tracker at https://github.com/util-linux/util-linux/issues.
AVAILABILITY
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/>.