How shall I understand the output of `NAME` field of `lsof`?

Question

$ sudo lsof +E -a -U -p 1480
lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1000/gvfs
      Output information may be incomplete.
lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1001/gvfs
      Output information may be incomplete.
COMMAND    PID USER   FD   TYPE             DEVICE SIZE/OFF  NODE NAME
Xorg       717 root   43u  unix 0xffff975eacf2d400      0t0 30862 @/tmp/.X11-unix/X0 type=STREAM ->INO=28661 1480,lxtermina,3u
dbus-daem  980    t   34u  unix 0xffff975eacf2fc00      0t0 30865 /run/user/1000/bus type=STREAM ->INO=28666 1480,lxtermina,9u
dbus-daem 1073    t   13u  unix 0xffff975eacf2c400      0t0 28664 @/tmp/dbus-vtzJFcQ5Cy type=STREAM ->INO=28663 1480,lxtermina,5u
lxtermina 1480    t    3u  unix 0xffff975eacf2c000      0t0 28661 type=STREAM ->INO=30862 717,Xorg,43u
lxtermina 1480    t    5u  unix 0xffff975eacf2d000      0t0 28663 type=STREAM ->INO=28664 1073,dbus-daem,13u
lxtermina 1480    t    7u  unix 0xffff975eacf2f000      0t0 28665 /run/user/1000/.lxterminal-socket- type=STREAM
lxtermina 1480    t    9u  unix 0xffff975eacf2e800      0t0 28666 type=STREAM ->INO=30865 980,dbus-daem,34u

In the NAME field, what are the meanings of INO=28664 and 13u in

type=STREAM ->INO=28664 1073,dbus-daem,13u

?

Thanks.

Answer 1

See the lsof manpage. Its description of the +E option says

Pipe endpoint information is displayed in the NAME column in the form “PID,cmd,FDmode”, where PID is the endpoint process ID; cmd is the endpoint process command; FD is the endpoint file's descriptor; and mode is the endpoint file's access mode.

UNIX socket file endpoint information is displayed in the NAME column in the form “type=TYPE ->INO=INODE PID,cmd,FDmode”, where TYPE is the socket type; INODE is the i-node number of the connected socket; and PID, cmd, FD and mode are the same as with pipe endpoint information. Note: UNIX socket file endpoint information is available only when the compile flags line of -v output contains HASUXSOCKEPT.

So INO=28664 means that the connected socket has inode number 28664, and 13u means that the endpoint’s file descriptor is 13, and its access mode is read/write.