LSOF Command Usage on RHEL 7
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This document provides a usage guide for the lsof command on RHEL 7. It describes what lsof is used for, pre-requisites, and examples of common commands to list open files by user, directory, process name, PID, network connections, and NFS files. The guide also explains how to use lsof to find processes associated with a specific file or running on a particular port.
![LSOF Usage Guide on RHEL 7
5 | P a g e
List of Open Files – By PID
To list files that are open by process id, run the command;
ps -ef | grep [m]ysqld_safe
lsof -p 1164
List Processes – By Specific File
To list the processes associated with a specific file, run the command;
lsof /var/log/Xorg.0.log](https://image.slidesharecdn.com/lsofusageguide-160602105625/85/LSOF-Command-Usage-on-RHEL-7-6-320.jpg)
LSOF Command Usage on RHEL 7
- 1. LSOF Usage Guide on RHEL 7 i | P a g e Table of Contents Overview.......................................................................................................................................................1 Applies To......................................................................................................................................................1 Pre-Requisites ...............................................................................................................................................1 Install Package...............................................................................................................................................1 Validate Package Installation........................................................................................................................1 File Descriptor Table .................................................................................................................................2 Type Descriptor Table...............................................................................................................................2 List of Opened Files – User............................................................................................................................3 List of Opened Files – Exclude User ..............................................................................................................3 List of Opened Files – Directory....................................................................................................................4 List of Open Files – By Process Name Starting With.....................................................................................4 List of Open Files – By PID.............................................................................................................................5 List Processes – By Specific File.....................................................................................................................5 List all Network Connections ........................................................................................................................6 List Network Connections – Only IPv4..........................................................................................................6 List Network Connections – Only IPv6..........................................................................................................6 List Network Connections – TCP Port Range ................................................................................................7 List Network Connections – UDP Port Range ...............................................................................................7 Find Processes Running – Specific Port.........................................................................................................7 List all network files in use by a specific process..........................................................................................7 List of Files in Repeat Mode..........................................................................................................................8 List of Files in Repeat Mode..........................................................................................................................8 List all NFS files..............................................................................................................................................9 Kill All process of a particular user................................................................................................................9
- 2. LSOF Usage Guide on RHEL 7 1 | P a g e Overview The purpose of this document is guide you the usage of “lsof” command. LSOF command is utilized to know the “LiSt of Open Files” by processes. As we are aware Linux / Unix considers everything as files such as (pipes, sockets, devices, etc.). This command is also useful when you want to unmount filesystem and but you are unable to unmount filesystem or process is running is memory. It is also useful wherein a file is deleted and file is resident in memory. lsof command will help us to find out files that are currently in use and its current state of such files. Applies To Tested on RHEL 7, CentOS 7. Pre-Requisites lsof package is installed Install Package LSOF package is installed by default in when you install operating system, in order to install the package if the package is not installed run the command; yum install -y lsof Validate Package Installation To verify the package installation status, run the command; rpm -qa | grep lsof
- 3. LSOF Usage Guide on RHEL 7 2 | P a g e First you need to understand the output of lsof command, below will give you a brief insight to different sections. FD and Types are the that we will focus upon, reset of the fields are self-explanatory. File Descriptor Table FD stands for File Descriptor and it has different values are listed when you the command. A few of them are listed below. File Descriptor Purpose cwd current working directory rtd root directory pd parent directory txt program text (code and data) mem memory-mapped file mmap Memory mapped device number character The character after the number i.e ‘1u’, represents the mode in which the file is opened. r for read, w for write, u for read and write. Type Descriptor Table Specifies the type of the file. Some of the values of TYPEs are, Type Descriptor Type of File REG Regular File DIR Directory FIFO First In First Out CHR Character special file
- 4. LSOF Usage Guide on RHEL 7 3 | P a g e List of Opened Files – User To list the files opened by a user, run the command; lsof -u chrony Note: To list of files that are open for multiple users run the command lsof -u mysql -u postfix. List of Opened Files – Exclude User To list of open files excluding a user(s), execute with option “-u” and “^” along with the user, run the command; lsof -u^root Note: To exclude results of additional users, run the command lsof -u ^mysql -u ^chrony -u ^dbus.
- 5. LSOF Usage Guide on RHEL 7 4 | P a g e List of Opened Files – Directory To list the files that are opened in a specific directory, run the command; lsof +D /var/log/ List of Open Files – By Process Name Starting With List the files that are open by process name(s) starting with, run the command; lsof -c mysql Note: To list of files that are open for multiple process names run the command lsof -c mysql -c systemd.
- 6. LSOF Usage Guide on RHEL 7 5 | P a g e List of Open Files – By PID To list files that are open by process id, run the command; ps -ef | grep [m]ysqld_safe lsof -p 1164 List Processes – By Specific File To list the processes associated with a specific file, run the command; lsof /var/log/Xorg.0.log
- 7. LSOF Usage Guide on RHEL 7 6 | P a g e List all Network Connections List all the network connections listening and established, run the command; lsof -i List Network Connections – Only IPv4 List all IPv4 network connections listening and established, run the command; lsof -i 4 List Network Connections – Only IPv6 List all IPv6 network connections listening and established, run the command; lsof -i 6
- 8. LSOF Usage Guide on RHEL 7 7 | P a g e List Network Connections – TCP Port Range List all the network connections listening and established for TCP port range, Run the command; lsof -i TCP:1-1024 List Network Connections – UDP Port Range List all the network connections listening and established for UDP port range, run the command; lsof -i UDP:1-1024 Find Processes Running – Specific Port To list the process running on a specific port, run the command; lsof -i :22 List all network files in use by a specific process To list all the network files which is being used by a process; run the command lsof -i -a -p 8132 or lsof -i -a -c ssh
- 9. LSOF Usage Guide on RHEL 7 8 | P a g e List of Files in Repeat Mode To list the files that are opened in repeat mode (loop until no files are open) “+” is prefixed before command “repeat option r” and refresh the output every 2 seconds, run the command; lsof -i -a -c ssh +r2 Note: Each cycle output is separated by “=======” List of Files in Repeat Mode To list the files that are opened in repeat mode (loop until interrupt “ctrl +c”) “-” is prefixed before command “repeat option r” and refresh the output every 5 seconds, run the command; lsof -i -a -c ssh -r5 Note: Each cycle output is separated by “=======”
- 10. LSOF Usage Guide on RHEL 7 9 | P a g e List all NFS files To list Network file system files in use, for a user. Run the command; lsof -N -u root -a Note: In this case there is NFS is not utilized. Kill All Process of a Particular User To list and kill all the process of a particular user; “-t” option will list only the process id of the user, run the command; lsof -t -u postfix kill -9 `lsof -t -u postfix`