lsof command in linux - Scaler Topics

Overview

In this article, we will discuss the lsof command in Linux, which stands for 'list open files'. The lsof command is a powerful utility that allows system administrators and users to view information about open files and the processes associated with them.

Linux lsof Command Syntax

The syntax for the lsof command is as follows:

Where:

options: A series of flags that can be used to filter and format the command output.
file: An optional argument that can be used to specify a particular file or directory to be listed.

lsof Command Options:

-a: This option is used to logically AND the results of other options and arguments.
-c: List open files by the command name or regular expression.
-i: List open files with specific Internet protocol, port number, or host.
-u: List open files by user name or user ID.

Example Usages

List all open files:
Output:
Explanation: Running lsof without any arguments will list all open files on the system along with information about the associated processes.
List open files for a specific user:
Output:
Explanation: Using the -u option followed by a username will display open files for that particular user.

Tips

Use the 'grep' command in conjunction with 'lsof' to filter results by a specific keyword.
To get a quick overview of network connections, use 'lsof -i'.

Advanced Use Cases of lsof Command in Linux

List open files by process ID:
Output:
Explanation: Using the -p option followed by a process ID will display open files for that particular process.
List open files with specific Internet protocol:
Output:
Explanation: Using the -i option followed by a protocol (e.g., tcp, udp) will display open files associated with that protocol.
List open files by command name or regular expression:
Output:
Explanation: Using the -c option followed by a command name or regular expression will display open files matching the criteria.

Conclusion

lsof is a powerful command for listing open files and their associated processes.
The command can be customized with various options and arguments to filter and format the output.
By understanding and utilizing the lsof command, system administrators and users can gain valuable insights into system processes and their open files.