10 lsof Command Examples in Linux

This is our on-going series of Linux commands and in this article we are going to review lsof command with practical examples. lsof meaning ‘LiSt Open Files’ is used to find out which files are open by which process. As we all know Linux/Unix considers everything as a files (pipes, sockets, directories, devices etc). One of the reason to use lsof command is when a disk cannot be unmounted as it says the files are being used. With the help of this command we can easily identify the files which are in use.

10 Linux lsof Command Examples

1. List all Open Files with lsof Command

In the below example, it will show long listing of open files some of them are extracted for better understanding which displays the columns like Command, PID, USER, FD, TYPE etc.

# lsof
COMMAND    PID      USER   FD      TYPE     DEVICE  SIZE/OFF       NODE NAME
init         1      root  cwd      DIR      253,0      4096          2 /
init         1      root  rtd      DIR      253,0      4096          2 /
init         1      root  txt      REG      253,0    145180     147164 /sbin/init
init         1      root  mem      REG      253,0   1889704     190149 /lib/libc-2.12.so
init         1      root   0u      CHR        1,3       0t0       3764 /dev/null
init         1      root   1u      CHR        1,3       0t0       3764 /dev/null
init         1      root   2u      CHR        1,3       0t0       3764 /dev/null
init         1      root   3r     FIFO        0,8       0t0       8449 pipe
init         1      root   4w     FIFO       0,8       0t0       8449 pipe
init         1      root   5r      DIR       0,10         0          1 inotify
init         1      root   6r      DIR       0,10         0          1 inotify
init         1      root   7u     unix 0xc1513880       0t0       8450 socket

Sections and it’s values are self-explanatory. However, we’ll review FD & TYPE columns more precisely.

FD – stands for File descriptor and may seen some of the values as:

1. cwd current working directory
2. rtd root directory
3. txt program text (code and data)
4. mem memory-mapped file

Also in FD column numbers like 1u is actual file descriptor and followed by u,r,w of it’s mode as:

1. r for read access.
2. w for write access.
3. u for read and write access.

TYPE – of files and it’s identification.

1. DIR – Directory
2. REG – Regular file
3. CHR – Character special file.
4. FIFO – First In First Out

2. List User Specific Opened Files

The below command will display the list of all opened files of user tecmint.

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