Lsof

wikipedia:lsof list open files and network connections.

Basic commands

• lsof /path/to/file or lsof /path/to/dir or lsof /dev/sdc1
• lsof -t /path/to/file

-t terse output with process identifiers only and no header

Files related

List all open files by a specific process:

• lsof -p PID
• lsof -u USERNAME
• lsof -a +L1 /path/to/fs (shows open, unlinked files) or lsof -nP | grep '(deleted)'
• lsof +D /path/to/dir

Network related

• lsof -i

Open TCP ports:

• lsof -iTCP -sTCP:LISTEN -P -n

Open UDP ports:

• lsof -iUDP -P -n

• macOS: sudo lsof -iTCP -sTCP:LISTEN -n -P

Related commands

• netstat, ss and netstat
• proc
• fuser
• lsof /dev/pts/*
• lsof -Pnl +c0 +M -i4

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/
3. Read https://www.akadia.com/services/lsof_quickstart.txt

See also

• lsof,strace, auditctl, fuser
• kill [-s], killall, pkill, xkill, podman kill, docker kill, SIGINT, SIGTERM, rfkill, killall5, kill 1, launchctl kill (macOS), kill -9, kill -15, signal
• 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/