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December 2014


Miscellaneous system utilities for Linux


lslocks - list local system locks


lslocks [options]


lslocks lists information about all the currently held file locks in a Linux system.
Note that lslocks also lists OFD (Open File Description) locks, these locks are not associated with any process (PID is -1). OFD locks are associated with the open file description on which they are acquired. This lock type is available since Linux 3.15, see fcntl(2) for more details.


-b, --bytes
Print the SIZE column in bytes rather than in a human-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 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.
-V, --version
Display version information and exit.
-h, --help
Display help text and exit.


COMMAND The command name of the process holding the lock.
PID The process ID of the process which holds the lock or -1 for OFDLCK.
TYPE The type of lock; can be 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.
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.


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


Davidlohr Bueso <>


The lslocks command is part of the util-linux package and is available from


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