Um, well, finally, I solved myself.
This problem is apparmor
.
Apparmor
blocked rserver
.
sudo aa-status
apparmor module is loaded.
48 profiles are loaded.
11 profiles are in enforce mode.
/sbin/dhclient
/usr/lib/NetworkManager/nm-dhcp-client.action
/usr/lib/NetworkManager/nm-dhcp-helper
/usr/lib/chromium-browser/chromium-browser//browser_java
/usr/lib/chromium-browser/chromium-browser//browser_openjdk
/usr/lib/chromium-browser/chromium-browser//sanitized_helper
/usr/lib/connman/scripts/dhclient-script
/usr/lib/rstudio-server/bin/rserver
/usr/lib/rstudio-server/bin/rserver//restricted
/usr/sbin/tcpdump
And i run command aa-remove-unknown
sudo aa-remove-unknown
Removing '/usr/lib/rstudio-server/bin/rserver'
Removing 'docker-default'
The rserver
acquires permission to use PAM.
It seems that even apparmor dones not know why it has blocked.
Anyway, thanks!
theodore