lslocks(8) — Linux manual page


LSLOCKS(8)                System Administration               LSLOCKS(8)

NAME         top

       lslocks - list local system locks

SYNOPSIS         top

       lslocks [options]

DESCRIPTION         top

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

OPTIONS         top

       -b, --bytes
           Print the sizes in bytes rather than in a human-readable

           By default, the unit, sizes are expressed in, is byte, and
           unit prefixes are in power of 2^10 (1024). Abbreviations of
           symbols are exhibited truncated in order to reach a better
           readability, by exhibiting alone the first letter of them;
           examples: "1 KiB" and "1 MiB" are respectively exhibited as
           "1 K" and "1 M", then omitting on purpose the mention "iB",
           which is part of these abbreviations.

       -H, --list-columns
           List the available columns, use with --json or --raw to get
           output in machine-readable format.

       -i, --noinaccessible
           Ignore lock files which are inaccessible for the current

       -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 available columns.

       -p, --pid pid
           Display only the locks held by the process with this pid.

       -r, --raw
           Use the raw output format.

       -u, --notruncate
           Do not truncate text in columns.

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

       -V, --version
           Print version and exit.

OUTPUT         top

           The command name of the process holding the lock.

           The process ID of the process.

           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 of the locked file.

           The inode number.

           The major:minor device number.

           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).

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

           Relative byte offset of the lock.

           Ending offset of the lock.

           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

           The PID of the process which blocks the lock.

           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.

NOTES         top

       The lslocks command is meant to replace the lslk(8) command,
       originally written by Victor A. Abell <> 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.

AUTHORS         top

       Davidlohr Bueso <>

SEE ALSO         top

       flock(1), fcntl(2), lockf(3)

REPORTING BUGS         top

       For bug reports, use the issue tracker at

AVAILABILITY         top

       The lslocks command is part of the util-linux package which can
       be downloaded from Linux Kernel Archive
       <>. This page
       is part of the util-linux (a random collection of Linux
       utilities) project. Information about the project can be found at
       ⟨⟩. If you have
       a bug report for this manual page, send it to This page was obtained from the
       project's upstream Git repository
       ⟨git://⟩ on
       2023-12-22. (At that time, the date of the most recent commit
       that was found in the repository was 2023-12-14.) 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

util-linux 2.39.1041-8a7c      2023-12-22                     LSLOCKS(8)

Pages that refer to this page: lsfd(1)fcntl(2)flock(2)proc(5)