linux command - lsof to see the process to open those files, or view file to use that process

Brief introduction

lsof (list open files) list the current system is a tool to open the file.

Format: lsof [options] [names]

Lsof output alone perform all open files in the system, we can grep to filter out what we care about, but lsof provide the appropriate parameters to help us pinpoint

lsof name the output file name using all processes

• -p pid pid list all files opened by processes
• -d FD_pattern lists the value of all the opened file is FD_pattern of FD FD are integers, TXT, MEM, etc.
• -A lsof can be added after a plurality of matching conditions, or default connection parameter into a plurality of conditions and relationships
• -i [46] [proto] [@hostname | ip] [: service | port] is used to select a port occupied by the process of
• + D / + D dir recursive or non-recursive display the file open process dir
• command -c string contained in string display process of the process of open files
• -u username display processes belonging to the user to open the file
• -g gid

Files can be opened:

1. Common file
2. table of Contents  
3. File Network File System
4. Character device file  
5. (Function) shared library  
6. Pipes, named pipes 
7. Symbolic link
8. word stream socket underlying network socket, UNIX domain socket
9. In linux inside, most of the things that are treated as files

Use lsof

Here it is mainly used in the form of cases to introduce the use of lsof command

1. List all open files:

lsof

NOTE: If no arguments, it will be open all open files, it is recommended to add about specific targeting parameters

2. Check who is using a file

lsof   /filepath/file

3. recursive view a catalog file information

lsof +D /filepath/filepath2/

Note: Use the + D, all subdirectories and files are listed under the corresponding directory

4. Use + D than the option to view a directory traversal method for all file information

lsof | grep ‘/filepath/filepath2/’

5. File information a user opens

lsof  -u username

Note: -u option, u actually is an acronym for the user

6. File information a program that opens

lsof -c mysql

Note: -c option will list all files that start with mysql program, in fact, you can also write  lsof | grep mysql,  but the first method is significantly less than a few characters to play second method

7. File information and more open multiple programs

lsof -c mysql -c apache

8. File information a user and a program that opens

lsof -u test -c mysql

9. In addition to the information listed files a user opened

lsof   -u ^root

NOTE: ^ this symbol before the username, the root user will open the process to prevent the display

10. Display the file be opened by a process ID

lsof -p 1

11. File information number corresponding to the multiple processes

lsof -p 123,456,789

12. File information in addition to a process ID number opened by other processes

lsof -p ^1

13. List all network connections

lsof -i

14. List all network connection information tcp

lsof  -i tcp

15. List all network connection information udp

lsof  -i udp

16. list who is using a port

lsof -i :3306

17. The list who is using a particular udp port

lsof -i udp:55

Specific tcp port

lsof -i tcp:80

18. List all active network ports for a user

lsof  -a -u test -i

19. List all Network File System

lsof -N

20. domain socket file

lsof -u

21. User Group opened a file information

lsof -g 5555

22. The file description information corresponding to the file listed in the

lsof -d description(like 2)

File information file 23. The description of a range

lsof -d 2-3