I do not know how to answer your first second question, but regarding the first one, you can use the +E flag for lsof to show the endpoint of the socket. From the man pages:

+|-E +E specifies that Linux pipe, Linux UNIX socket and Linux pseudoterminal files should be displayed with endpoint information and the files of the endpoints should also be displayed

For instance, here's some example from a question someone had where he was trying to find out the endpoint of fd 6 of a top process:

# lsof -d 6 -U -a +E -p $(pgrep top) COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME dbus-daem 874 messagebus 12u unix 0xffff9545f6fee400 0t0 366381191 /var/run/dbus/system_bus_socket type=STREAM ->INO=366379599 25127,top,6u top 25127 root 6u unix 0xffff9545f6fefc00 0t0 366379599 type=STREAM ->INO=366381191 874,dbus-daem,12u 

The -U flag for lsof shows only Unix socket files.

Notice that you will only see the name of the socket file for the listening processes. The other process will not show the name of the unix socket file, but with +E lsof will show the inode of the listening socket file, and will also add a line for the process listening to this socket (along with the socket file name).

In this example notice that we only asked lsof to show the file descriptors of top command, but lsof added another line for dbus-daem - which is the listening process, and the socket file it listens to is /var/run/dbus/system_bus_socket.

• Pid 25127 (inode 366379599) interacts with inode 366381191 (type=STREAM ->INO=366381191 874,dbus-daem,12u)
• Inode 366381191 belong to pid 874, and you can see this process has the fd that is the listening side for the second process (/var/run/dbus/system_bus_socket type=STREAM ->INO=366379599 25127,top,6u), and there you can see that the socket file name is /var/run/dbus/system_bus_socket.

To find the file associated with the UNIX socket, you can use the +E flag for lsof to show the endpoint of the socket. From the man pages:

+|-E +E specifies that Linux pipe, Linux UNIX socket and Linux pseudoterminal files should be displayed with endpoint information and the files of the endpoints should also be displayed

For instance, here's some example from a question someone had where he was trying to find out the endpoint of fd 6 of a top process:

# lsof -d 6 -U -a +E -p $(pgrep top) COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME dbus-daem 874 messagebus 12u unix 0xffff9545f6fee400 0t0 366381191 /var/run/dbus/system_bus_socket type=STREAM ->INO=366379599 25127,top,6u top 25127 root 6u unix 0xffff9545f6fefc00 0t0 366379599 type=STREAM ->INO=366381191 874,dbus-daem,12u 

The -U flag for lsof shows only Unix socket files.

Notice that you will only see the name of the socket file for the listening processes. The other process will not show the name of the unix socket file, but with +E lsof will show the inode of the listening socket file, and will also add a line for the process listening to this socket (along with the socket file name).

In this example notice that we only asked lsof to show the file descriptors of top command, but lsof added another line for dbus-daem - which is the listening process, and the socket file it listens to is /var/run/dbus/system_bus_socket.

• Pid 25127 (inode 366379599) interacts with inode 366381191 (type=STREAM ->INO=366381191 874,dbus-daem,12u)
• Inode 366381191 belong to pid 874, and you can see this process has the fd that is the listening side for the second process (/var/run/dbus/system_bus_socket type=STREAM ->INO=366379599 25127,top,6u), and there you can see that the socket file name is /var/run/dbus/system_bus_socket.

Also, how can I interact with it?

Now that you have the filename of the UNIX socket, you can interact with it in various ways, such as:

socat - UNIX-CONNECT:/run/dbus/system_bus_socket nc -U /run/dbus/system_bus_socket 

For additional information: How can I communicate with a Unix domain socket via the shell on Debian Squeeze?

I do not know how to answer your first second question, but regarding the first one, you can use the +E flag for lsof to show the endpoint of the socket. From the man pages:

+|-E +E specifies that Linux pipe, Linux UNIX socket and Linux pseudoterminal files should be displayed with endpoint information and the files of the endpoints should also be displayed

For instance, here's some example from a question someone had where he was trying to find out the endpoint of fd 6 of a top process:

# lsof -d 6 -U -a +E -p $(pgrep top) COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME dbus-daem 874 messagebus 12u unix 0xffff9545f6fee400 0t0 366381191 /var/run/dbus/system_bus_socket type=STREAM ->INO=366379599 25127,top,6u top 25127 root 6u unix 0xffff9545f6fefc00 0t0 366379599 type=STREAM ->INO=366381191 874,dbus-daem,12u 

The -U flag for lsof shows only Unix socket files.

I do not know how to answer your first second question, but regarding the first one, you can use the +E flag for lsof to show the endpoint of the socket. From the man pages:

+|-E +E specifies that Linux pipe, Linux UNIX socket and Linux pseudoterminal files should be displayed with endpoint information and the files of the endpoints should also be displayed

For instance, here's some example from a question someone had where he was trying to find out the endpoint of fd 6 of a top process:

# lsof -d 6 -U -a +E -p $(pgrep top) COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME dbus-daem 874 messagebus 12u unix 0xffff9545f6fee400 0t0 366381191 /var/run/dbus/system_bus_socket type=STREAM ->INO=366379599 25127,top,6u top 25127 root 6u unix 0xffff9545f6fefc00 0t0 366379599 type=STREAM ->INO=366381191 874,dbus-daem,12u 

The -U flag for lsof shows only Unix socket files.

Notice that you will only see the name of the socket file for the listening processes. The other process will not show the name of the unix socket file, but with +E lsof will show the inode of the listening socket file, and will also add a line for the process listening to this socket (along with the socket file name).

In this example notice that we only asked lsof to show the file descriptors of top command, but lsof added another line for dbus-daem - which is the listening process, and the socket file it listens to is /var/run/dbus/system_bus_socket.

• Pid 25127 (inode 366379599) interacts with inode 366381191 (type=STREAM ->INO=366381191 874,dbus-daem,12u)
• Inode 366381191 belong to pid 874, and you can see this process has the fd that is the listening side for the second process (/var/run/dbus/system_bus_socket type=STREAM ->INO=366379599 25127,top,6u), and there you can see that the socket file name is /var/run/dbus/system_bus_socket.