Lsof

lsof list open files and network connections.

Basic commands

• lsof -t /path/to/file
• lsof /path/to/file

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

See also: netstat and ss

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

• strace
• kill

ip [link, route], ifconfig netstat ss lsof ping ethtool mii-tool arping nmcli(RHEL) route networkctl, netplan, tc