LSLOCKS(8)                   System Administration                  LSLOCKS(8)

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 =~ ".*\.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 lock's access permissions (read, write). If the process is
           blocked and waiting for the lock, then the mode is postfixed with
           an '*' (asterisk).

       M
           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 device's
           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 Victor A. Abell <abe@purdue.edu> 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
       Davidlohr Bueso <dave@gnu.org> Christian Goeschel Ndjomouo
       <cgoesc2@wgu.edu>

SEE ALSO
       flock(1), fcntl(2), lockf(3), scols-filter(5)

REPORTING BUGS
       For bug reports, use the issue tracker
       <https://github.com/util-linux/util-linux/issues>.

AVAILABILITY
       The lslocks 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/>.

util-linux 2.42.1                 2026-05-18                        LSLOCKS(8)