Lsof

lsof list open files and network connections.

Basic commands

• lsof -t /path/to/file

-t terse output with process identifiers only and no header

• lsof /path/to/file or lsof /path/to/dir

List all open files by a specific process:

• lsof -p PID

• lsof -u USERNAME

Network related

• lsof -i

Open TCP ports:

• lsof -iTCP -sTCP:LISTEN -P -n

Open UDP ports:

• lsof -iUDP -P -n

Related commands

• netstat, ss and netstat
• proc
• fuser

Activities

1. Read lsof questions on StackExchange: https://unix.stackexchange.com/questions/tagged/lsof?tab=Votes
2. Review further examples in https://www.thegeekstuff.com/2012/08/lsof-command-examples/

See also

• lsof,strace, auditctl, fuser
• kill
• ip [link, route], ifconfig netstat ss lsof ping ethtool mii-tool arping nmcli(RHEL) route networkctl, netplan, tc, networkd-dispatcher
• file, File system, directory, touch, mkdir, ls, ln truncate, fallocate, split, stat, inode, File descriptor, superblock, block size (blockdev), fuser, lsof, scrub, chattr, ulimit (nofiles), cp, mv, file (command), mkfifo, chmod

http://man7.org/linux/man-pages/man8/lsof.8.html

https://www.thegeekstuff.com/2012/08/lsof-command-examples/