Lsof: Difference between revisions
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The command provides file descriptor information by default, as the fourth field "FD". The FD column contents constitutes a single field for parsing in post-processing scripts. | The command provides file descriptor information by default, as the fourth field "FD". The FD column contents constitutes a single field for parsing in post-processing scripts. | ||
The FD column content | The FD column content starts with the file descriptor number, followed by one character describing the mode under which the file is open. If the FD does not start with a file descriptor number, it is one of the [[Special_Entries|special entires]] described below. | ||
* 'r' for read access | * 'r' for read access | ||
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* 'U' for a lock of unknown type | * 'U' for a lock of unknown type | ||
* space if there is no lock | * space if there is no lock | ||
==Special Entries== | |||
Special entries do not start with a file descriptor number and marked as such: | Special entries do not start with a file descriptor number and marked as such: | ||
Revision as of 16:56, 3 May 2017
Internal
Overview
lsof lists information about files opened by processes. lsof provides information about:
- regular files
- directories
- block special files
- character special files
- executing text references
- libraries
- streams
- network files (Internet socket, NFS file or UNIX domain socket)
In absence of any options, lsof lists all open files by all processes.
To list open files by a specific process, use the process' PID as follows:
lsof -p <pid>
The output is similar to:
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME java 10016 vagrant cwd DIR 252,2 4096 2621584 /home/test java 10016 vagrant rtd DIR 252,0 4096 2 / java 10016 vagrant txt REG 252,2 7734 2885001 /opt/java/x64/jre1.8.0_51/bin/java java 10016 vagrant mem REG 252,0 161704 1310723 /lib64/ld-2.12.so [...] java 10016 vagrant 0r CHR 1,3 0t0 26 /dev/null java 10016 vagrant 1u CHR 136,0 0t0 3 /dev/pts/0 (deleted) java 10016 vagrant 2u CHR 136,0 0t0 3 /dev/pts/0 (deleted) java 10016 vagrant 3w REG 252,2 48759 2753619 /home/test/gc.log.0.current java 10016 vagrant 4r REG 252,2 65944582 2884909 /opt/java/x64/jre1.8.0_51/lib/rt.jar java 10016 vagrant 5u IPv4 39331 0t0 TCP *:msgsrvr (LISTEN) [...]
File Descriptor Information
The command provides file descriptor information by default, as the fourth field "FD". The FD column contents constitutes a single field for parsing in post-processing scripts.
The FD column content starts with the file descriptor number, followed by one character describing the mode under which the file is open. If the FD does not start with a file descriptor number, it is one of the special entires described below.
- 'r' for read access
- 'w' for write access
- 'u' for read and write access
- space if mode is unknown and no lock character follows
- ‘-’ if mode unknown and lock character follows
The mode character is followed by one of these lock characters, describing the type of lock applied to the file:
- 'r' for read lock on part of the file
- 'R' for a read lock on the entire file
- 'w' for a write lock on part of the file
- 'W' for a write lock on the entire file
- 'u' for a read and write lock of any length
- 'U' for a lock of unknown type
- space if there is no lock
Special Entries
Special entries do not start with a file descriptor number and marked as such:
- cwd current working directory
- err FD information error (see NAME column)
- jld" jail directory (FreeBSD)
- ltx shared library text (code and data)
- Mxx hex memory-mapped type number xx
- m86 DOS Merge mapped file
- mem memory-mapped file
- mmap memory-mapped device
- pd parent directory
- rtd root directory
- tr kernel trace file (OpenBSD)
- txt program text (code and data)
- v86 VP/ix mapped file