# proc_locks - current file locks and leases - man(5) - [phpMan]

[_proc_locks_(5)](https://www.chedong.com/phpMan.php/man/proclocks/5/markdown)                            File Formats Manual                           [_proc_locks_(5)](https://www.chedong.com/phpMan.php/man/proclocks/5/markdown)

## NAME
       /proc/locks - current file locks and leases

## DESCRIPTION
       _/proc/locks_
              This file shows current file locks ([**flock**(2)](https://www.chedong.com/phpMan.php/man/flock/2/markdown) and [**fcntl**(2)](https://www.chedong.com/phpMan.php/man/fcntl/2/markdown)) and leases ([**fcntl**(2)](https://www.chedong.com/phpMan.php/man/fcntl/2/markdown)).

              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)](https://www.chedong.com/phpMan.php/man/flock/2/markdown).

                   **OFDLCK **This is an open file description (OFD) lock created using [**fcntl**(2)](https://www.chedong.com/phpMan.php/man/fcntl/2/markdown).

                   **POSIX  **This is a POSIX byte-range lock created using [**fcntl**(2)](https://www.chedong.com/phpMan.php/man/fcntl/2/markdown).

              [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 al‐
                   ways 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)](https://www.chedong.com/phpMan.php/man/pidnamespaces/7/markdown)) 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)](https://www.chedong.com/phpMan.php/man/lslocks/8/markdown) command provides a bit more information about each lock.

## SEE ALSO
       [**proc**(5)](https://www.chedong.com/phpMan.php/man/proc/5/markdown)

Linux man-pages 6.7                          2023-11-19                                [_proc_locks_(5)](https://www.chedong.com/phpMan.php/man/proclocks/5/markdown)