【X11vnc】Ubuntu18.04 x11vnc启动失败，报错error opening logfile: /var/log/x11vnc.log

root@VM-16-8-ubuntu:/home/ubuntu# cat /var/log/x11vnc.log | head -n 1000
14/10/2021 10:30:02 passing arg to libvncserver: -rfbauth
14/10/2021 10:30:02 passing arg to libvncserver: /etc/x11vnc.pass
14/10/2021 10:30:02 passing arg to libvncserver: -rfbport
14/10/2021 10:30:02 passing arg to libvncserver: 5900
14/10/2021 10:30:02 x11vnc version: 0.9.13 lastmod: 2011-08-10  pid: 96503
xauth:  unable to generate an authority file name
14/10/2021 10:30:02 -auth guess: using 'XAUTHORITY=/var/run/lightdm/root/:0' for disp='unset'
14/10/2021 10:30:02 XOpenDisplay("") failed.
14/10/2021 10:30:02 Trying again with XAUTHLOCALHOSTNAME=localhost ...
14/10/2021 10:30:02 
14/10/2021 10:30:02 *** XOpenDisplay failed. No -display or DISPLAY.
14/10/2021 10:30:02 *** Trying ":0" in 4 seconds.  Press Ctrl-C to abort.
14/10/2021 10:30:02 *** 1 2 3 4 
14/10/2021 10:30:06 *** XOpenDisplay of ":0" successful.
14/10/2021 10:30:06 
14/10/2021 10:30:06 Using X display :0
14/10/2021 10:30:06 rootwin: 0x2a0 reswin: 0xe00001 dpy: 0xc6786c40
14/10/2021 10:30:06 
14/10/2021 10:30:06 ------------------ USEFUL INFORMATION ------------------
14/10/2021 10:30:06 
14/10/2021 10:30:06 Wireframing: -wireframe mode is in effect for window moves.
14/10/2021 10:30:06   If this yields undesired behavior (poor response, painting
14/10/2021 10:30:06   errors, etc) it may be disabled:
14/10/2021 10:30:06    - use '-nowf' to disable wireframing completely.
14/10/2021 10:30:06    - use '-nowcr' to disable the Copy Rectangle after the
14/10/2021 10:30:06      moved window is released in the new position.
14/10/2021 10:30:06   Also see the -help entry for tuning parameters.
14/10/2021 10:30:06   You can press 3 Alt_L's (Left "Alt" key) in a row to 14/10/2021 10:30:06 repaint the screen, also see the -fixscreen option for 14/10/2021 10:30:06 periodic repaints. 14/10/2021 10:30:06 14/10/2021 10:30:06 XFIXES available on display, resetting cursor mode 14/10/2021 10:30:06 to: '-cursor most'. 14/10/2021 10:30:06 to disable this behavior use: '-cursor arrow' 14/10/2021 10:30:06 or '-noxfixes'. 14/10/2021 10:30:06 using XFIXES for cursor drawing. 14/10/2021 10:30:06 GrabServer control via XTEST. 14/10/2021 10:30:06 14/10/2021 10:30:06 Scroll Detection: -scrollcopyrect mode is in effect to 14/10/2021 10:30:06 use RECORD extension to try to detect scrolling windows 14/10/2021 10:30:06 (induced by either user keystroke or mouse input). 14/10/2021 10:30:06 If this yields undesired behavior (poor response, painting 14/10/2021 10:30:06 errors, etc) it may be disabled via: '-noscr' 14/10/2021 10:30:06 Also see the -help entry for tuning parameters. 14/10/2021 10:30:06 You can press 3 Alt_L's (Left "Alt" key) in a row to 
14/10/2021 10:30:06   repaint the screen, also see the -fixscreen option for
14/10/2021 10:30:06   periodic repaints.
14/10/2021 10:30:06 
14/10/2021 10:30:06 XKEYBOARD: number of keysyms per keycode 7 is greater
14/10/2021 10:30:06   than 4 and 51 keysyms are mapped above 4.
14/10/2021 10:30:06   Automatically switching to -xkb mode.
14/10/2021 10:30:06   If this makes the key mapping worse you can
14/10/2021 10:30:06   disable it with the "-noxkb" option.
14/10/2021 10:30:06   Also, remember "-remap DEAD" for accenting characters.
14/10/2021 10:30:06 
14/10/2021 10:30:06 X FBPM extension not supported.
14/10/2021 10:30:06 X display is capable of DPMS.
14/10/2021 10:30:06 --------------------------------------------------------
14/10/2021 10:30:06 
14/10/2021 10:30:06 Default visual ID: 0x21
14/10/2021 10:30:06 Read initial data from X display into framebuffer.
14/10/2021 10:30:06 initialize_screen: fb_depth/fb_bpp/fb_Bpl 24/32/4096
14/10/2021 10:30:06 
14/10/2021 10:30:06 X display :0 is 32bpp depth=24 true color
14/10/2021 10:30:06 
14/10/2021 10:30:06 Listening for VNC connections on TCP port 5900
14/10/2021 10:30:06 Listening for VNC connections on TCP6 port 5900
14/10/2021 10:30:06 listen6: bind: Address already in use
14/10/2021 10:30:06 Not listening on IPv6 interface.
14/10/2021 10:30:06 
14/10/2021 10:30:06 Xinerama is present and active (e.g. multi-head).
14/10/2021 10:30:06 Xinerama: number of sub-screens: 1
14/10/2021 10:30:06 Xinerama: no blackouts needed (only one sub-screen)
14/10/2021 10:30:06 
14/10/2021 10:30:06 fb read rate: 927 MB/sec
14/10/2021 10:30:06 fast read: reset -wait  ms to: 10
14/10/2021 10:30:06 fast read: reset -defer ms to: 10
14/10/2021 10:30:06 The X server says there are 10 mouse buttons.
14/10/2021 10:30:06 screen setup finished.
14/10/2021 10:30:06 
The VNC desktop is:      VM-16-8-ubuntu:0
******************************************************************************
Have you tried the x11vnc '-ncache' VNC client-side pixel caching feature yet?
The scheme stores pixel data offscreen on the VNC viewer side for faster
retrieval.  It should work with any VNC viewer.  Try it by running:
x11vnc -ncache 10 ...
One can also add -ncache_cr for smooth 'copyrect' window motion.
More info: http://www.karlrunge.com/x11vnc/faq.html#faq-client-caching