NAME

       /proc/locks - current file locks and leases

DESCRIPTION

       /proc/locks
              This file shows current file locks (flock(2) and fcntl(2)) and leases (fcntl(2)).

              An example of the content shown in this file is the following:

                  1: POSIX  ADVISORY  READ  5433 08:01:7864448 128 128
                  2: FLOCK  ADVISORY  WRITE 2001 08:01:7864554 0 EOF
                  3: FLOCK  ADVISORY  WRITE 1568 00:2f:32388 0 EOF
                  4: POSIX  ADVISORY  WRITE 699 00:16:28457 0 EOF
                  5: POSIX  ADVISORY  WRITE 764 00:16:21448 0 0
                  6: POSIX  ADVISORY  READ  3548 08:01:7867240 1 1
                  7: POSIX  ADVISORY  READ  3548 08:01:7865567 1826 2335
                  8: OFDLCK ADVISORY  WRITE -1 08:01:8713209 128 191

              The fields shown in each line are as follows:

              [1]  The ordinal position of the lock in the list.

              [2]  The lock type.  Values that may appear here include:

                   FLOCK  This is a BSD file lock created using flock(2).

                   OFDLCK This is an open file description (OFD) lock created using fcntl(2).

                   POSIX  This is a POSIX byte-range lock created using fcntl(2).

              [3]  Among the strings that can appear here are the following:

                   ADVISORY
                          This is an advisory lock.

                   MANDATORY
                          This is a mandatory lock.

              [4]  The type of lock.  Values that can appear here are:

                   READ   This is a POSIX or OFD read lock, or a BSD shared lock.

                   WRITE  This is a POSIX or OFD write lock, or a BSD exclusive lock.

              [5]  The PID of the process that owns the lock.

                   Because  OFD locks are not owned by a single process (since multiple processes
                   may have file descriptors that refer to the same open file  description),  the
                   value  -1 is displayed in this field for OFD locks.  (Before Linux 4.14, a bug
                   meant that the PID of  the  process  that  initially  acquired  the  lock  was
                   displayed instead of the value -1.)

              [6]  Three colon-separated subfields that identify the major and minor device ID of
                   the device containing the filesystem where the locked file  resides,  followed
                   by the inode number of the locked file.

              [7]  The  byte  offset of the first byte of the lock.  For BSD locks, this value is
                   always 0.

              [8]  The byte offset of the last byte of the lock.  EOF in this  field  means  that
                   the  lock  extends  to the end of the file.  For BSD locks, the value shown is
                   always EOF.

              Since Linux 4.9, the list of locks shown in /proc/locks is filtered  to  show  just
              the  locks for the processes in the PID namespace (see pid_namespaces(7)) for which
              the /proc filesystem was mounted.  (In the  initial  PID  namespace,  there  is  no
              filtering of the records shown in this file.)

              The lslocks(8) command provides a bit more information about each lock.

SEE ALSO

       proc(5)