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lslocks - Man Page

list local system locks

Examples (TL;DR)

Synopsis

lslocks [options]

Description

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

Options

-b,  --bytes

Print the sizes in bytes rather than in a human-readable format.

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 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.

-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

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.

Notes

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

Davidlohr Bueso

See Also

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

Reporting Bugs

For bug reports, use the issue tracker at 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.

Referenced By

fcntl(2), flock(2), lsfd(1), proc_locks(5).

2024-05-01 util-linux 2.40.1 System Administration