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You are here: manpages

LSLOCKS

Section: System Administration (8)
Updated: 202-0-04
Index Return to Main Contents

NAME

lslocks - list local system locks

SYNOPSIS

lslocks [options]

DESCRIPTION

lslocks lists information about all the currently held file locks in a Linux system.

OPTIONS

-b, --bytes

: Print sizes in bytes rather than in human-readable form.
By default, sizes are shown in units that are powers of 1024 bytes. The formal abbreviations for these units (KiB, MiB, GiB, ...) are further shortened to just their first letter: K, M, G, ....

-H, --list-columns

: List the columns that can be specified with the --output option. Can be used with --json or --raw to get the list in a machine-readable format.

-i, --noinaccessible

: Ignore lock files which are inaccessible for the current user.

-J, --json

: Use JSON output format.

-n, --noheadings

: Do not print a header line.

-o, --output list

: Specify which output columns to print. Use --help to get a list of all supported columns.
The default list of columns may be extended if list is specified in the format +list (e.g., lslocks -o +BLOCKER).

--output-all

: Output all available columns.

-p, --pid pid

: Display only the locks held by the process with this pid.

-Q, --filter expr

: Print only the locks that meet the conditions specified by the expr.
This feature is EXPERIMENTAL. See also scols-filter(5). For example exclude POSIX type locks, but print all READ mode ones locks on files with .qcow2 as extension:

lslocks --filter 'TYPE != "POSIX" and MODE == "READ" and PATH =~ ".*rs.qcow2"'

-r, --raw

: Use the raw output format.

-u, --notruncate

: Do not truncate text in columns.

-h, --help

: Display help text and exit.

-V, --version

: Display version and exit.

ENVIRONMENT

LIBSMARTCOLS_DEBUG=all

: enables libsmartcols debug output.

LIBSMARTCOLS_DEBUG_PADDING=on

: use visible padding characters.

LIBSMARTCOLS_JSON=compact|lines

: Controls JSON output format when using --json. Supported values are compact for JSON output with minimal whitespace, and lines for JSON Lines format (one JSON object per line). If unset or set to any other value, pretty-printed JSON is used.

OUTPUT

COMMAND

: The command name of the process holding the lock.

PID

: The process ID of the process.

TYPE

: The type of lock; can be LEASE (created with fcntl(2)), FLOCK (created with flock(2)), POSIX (created with fcntl(2) and lockf(3)) or OFDLCK (created with fcntl(2)).

SIZE

: Size of the locked file.

INODE

: The inode number.

MAJ:MIN

: The major:minor device number.

MODE

: The lockcqs access permissions (read, write). If the process is blocked and waiting for the lock, then the mode is postfixed with an '*' (asterisk).

: Whether the lock is mandatory; 0 means no (meaning the lock is only advisory), 1 means yes. (See fcntl(2).)

START

: Relative byte offset of the lock.

END

: Ending offset of the lock.

PATH

: Full path of the lock. If none is found, or there are no permissions to read the path, it will fall back to the devicecqs mountpoint and "..." is appended to the path. The path might be truncated; use --notruncate to get the full path.

BLOCKER

: The PID of the process which blocks the lock.

HOLDERS

: The holder(s) of the lock. The format of the holder is PID,COMMAND,FD. If a lock is an open file description-oriented lock, there can be more than one holder for the lock. See the NOTES below.

ENVIRONMENT

LSLOCKS_COLUMNS=

: Specifies a comma-separated list of output columns to print. All columns listed by --list-columns can be used.

NOTES

The lslocks command is meant to replace the lslk(8) command, originally written by and unmaintained since 2001.

"The process holding the lock" for leases, FLOCK locks, and OFD locks is a fake-concept. They are associated with the open file description on which they are acquired. With fork(2) and/or cmsg(3), multiple processes can share an open file description. So the holder process of a lease (or a lock) is not uniquely determined. lslocks shows the one of the holder processes in COMMAND and PID columns.

The default output is subject to change. So whenever possible, you should avoid using default output in your scripts.

For OFD locks, the PID column may show -1. Such lines cannot be selected by the filter, because the current filter engine does not support negative numbers.

AUTHORS

REPORTING BUGS

For bug reports, use the https://github.com/uti-linux/uti-linux/issues <L>issue tracker

AVAILABILITY

The lslocks command is part of the util-linux package which can be downloaded from https://www.kernel.org/pub/linux/utils/uti-linux/ <L>Linux Kernel Archive