How to list/track open files in Linux with lsof command?
In Linux systems, an open file is a file that is being accessed by a process. This can include files that are being read, written, or executed. It is often useful to be able to list or track open files in Linux, particularly when troubleshooting issues or analyzing system resources.
One tool that can be used to list and track open files (and their processes) in Linux is the lsof command. lsof stands for "List Open Files", and it is a utility that allows users to view a list of all open files on a system. In this article, we will explore the usage of lsof command.
How to install lsof command in Linux?
There's a strong probability that lsof is already set up on your computer. Open terminal, and try running lsof command. If it isn't, you can install it using the package manager for your distro.
Debian/Ubuntu - apt install lsof
Alpine - apk add lsof
Arch Linux - pacman -S lsof
CentOS - yum install lsof
Fedora - dnf install lsof
OS X - brew install lsof
Dockerfile - dockerfile.run/lsof
Docker - docker run cmd.cat/lsof lsof
How to use lsof command in Linux?
1. To list all open files on a system, simply enter the lsof command with no arguments in the terminal:
$ lsof
This will display a list of all open files (which you have access to), including the process ID (PID) of the process that has the file open, the user that owns the process, the file descriptor (FD), and the file name.
2. By default, lsof will only display open files that are associated with active processes. If you want to include open files that are associated with inactive processes (such as deleted files), you can use the -a flag:
$ lsof -a
3. You can also use the lsof command to list open files for a specific process. To do this, you can use the -p flag followed by the PID of the process:
$ lsof -p 799
This will display a list of all open files for the process with PID 799.
4. You can also use the lsof command to list open files for a specific user. To do this, you can use the -u flag followed by a username:
$ lsof -u username
This will display a list of all open files for the specified user.
The lsof command also supports a number of other options and flags that can be used to customize the output or filter the list of open files. For a complete list of options and flags, you can consult the lsof man page by entering the following command: man lsof
Conclusion
In this article, we have discussed how to use the lsof command to list and track open files in Linux. We have covered the installation of lsof command in different Linux distributions, basic syntax of the lsof command, as well as some common options and flags that can be used to customize the output or filter the list of open files.
