lsof

View files open by PID (using pgrep in subcommand for convenience):

lsof -p $(pgrep -f "python3 sock_stream_server.py")

View sockets by port or address

lsof -i TCP:22
lsof -i [email protected]

Inspect unix sockets, and even get their type:

~$ lsof -U | grep foo

python3   130385 mierdin    3u  unix 0x0000000000000000      0t0 1382094 /tmp/foo.sock type=SEQPACKET

Get unix sockets:

1mierdin@t-bug:~ $ lsof -U | sed -n '1p; /python3/p'
2COMMAND      PID    USER   FD   TYPE             DEVICE SIZE/OFF   NODE NAME
3python3   100466 mierdin    3u  unix 0x000000009cf5d8f7      0t0 231914 /tmp/myunixsocket.sock type=SEQPACKET (LISTEN)
4python3   100466 mierdin    4u  unix 0x00000000d52bc0de      0t0 231915 /tmp/myunixsocket.sock type=SEQPACKET (CONNECTED)
5python3   100467 mierdin    3u  unix 0x0000000090965ca3      0t0 230698 type=SEQPACKET (CONNECTED)