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NAME | DESCRIPTION | SEE ALSO | COLOPHON |
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proc_locks(5) File Formats Manual proc_locks(5)
/proc/locks - current file locks and leases
/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.
proc(5)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. 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
man-pages@man7.org
Linux man-pages 6.9.1 2024-05-02 proc_locks(5)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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