我的屏幕（nvidia）和扫描仪（Epson V330）出现了一些奇怪的现象，我的系统日志不时显示此消息
Oct 25 19:52:30 lrkwz-Precision-M4500 gsd-color[5655]: failed to set screen _ICC_PROFILE: Failed to open file “/var/lib/gdm3/.local/share/icc/edid-c16ba004ffc69e8889a4dfc31cb00abb.icc”: Permission denied
Oct 25 19:52:32 lrkwz-Precision-M4500 gsd-color[5655]: message repeated 3 times: [ failed to set screen _ICC_PROFILE: Failed to open file “/var/lib/gdm3/.local/share/icc/edid-c16ba004ffc69e8889a4dfc31cb00abb.icc”: Permission denied]
为什么是/var/lib/gdm3/.local只读的？
$ sudo ls -l /var/lib/gdm3/.local/share/icc/edid-c16ba004ffc69e8889a4dfc31cb00abb.icc
-rw-rw-r-- 1 gdm gdm 1420 set 1 00:05 /var/lib/gdm3/.local/share/icc/edid-c16ba004ffc69e8889a4dfc31cb00abb.icc
完整的树是：
$ sudo ls -la /var/lib/gdm3/.local/share/icc/edid-c16ba004ffc69e8889a4dfc31cb00abb.icc /var/lib/gdm3/.local/share/icc/ /var/lib/gdm3/.local/share/ /var/lib/gdm3/.local/ /var/lib/gdm3/ /var/lib/
-rw-rw-r-- 1 gdm gdm 1420 set 1 00:05 /var/lib/gdm3/.local/share/icc/edid-c16ba004ffc69e8889a4dfc31cb00abb.icc
/var/lib/:
total 272
drwxr-xr-x 68 root root 4096 ott 27 23:33 .
drwxr-xr-x 14 root root 4096 lug 25 05:14 ..
drwxr-xr-x 4 root root 4096 lug 25 05:05 AccountsService
drwxr-xr-x 2 root root 4096 mag 1 2013 acpi-support
drwxr-xr-x 2 root root 4096 ott 28 18:36 alsa
drwxr-xr-x 4 root root 4096 ott 29 10:57 app-info
drwxr-xr-x 2 root root 4096 set 14 11:19 apport
drwxr-xr-x 5 root root 4096 ott 28 11:23 apt
drwxr-xr-x 2 root root 4096 lug 25 05:10 aspell
drwxr-xr-x 2 avahi-autoipd avahi-autoipd 4096 lug 25 05:08 avahi-autoipd
drwxr-xr-x 3 root root 4096 ago 31 23:41 bluetooth
drwxr-xr-x 2 root root 4096 mag 25 10:47 boltd
drwxr-xr-x 4 colord colord 4096 set 1 00:05 colord
drwxr-xr-x 2 root root 4096 mag 5 08:41 command-not-found
drwxr-xr-x 2 root root 4096 set 1 00:05 dbus
drwxr-xr-x 2 root root 4096 apr 16 2018 dhcp
drwxr-xr-x 4 root root 4096 lug 25 05:08 dictionaries-common
drwxr-xr-x 3 root root 4096 set 14 14:13 dkms
drwx--x--x 15 root root 4096 ott 29 10:57 docker
drwxr-xr-x 7 root root 4096 ott 28 11:23 dpkg
drwxr-xr-x 3 root root 4096 lug 25 05:06 emacsen-common
drwxr-xr-x 5 root root 4096 set 1 00:06 fwupd
drwxr-xr-x 2 root root 4096 feb 14 2018 fwupdate
drwxr-xr-x 5 root root 4096 set 1 00:35 gconf
drwxr-xr-x 6 gdm gdm 4096 ott 29 10:57 gdm3
drwxr-xr-x 3 root root 4096 ott 19 15:16 gems
drwxr-xr-x 3 geoclue geoclue 4096 set 1 00:05 geoclue
drwxr-xr-x 4 root root 4096 lug 25 05:06 ghostscript
drwxr-xr-x 2 root root 4096 mag 31 19:50 git
drwxr-xr-x 2 root root 4096 set 11 17:09 hp
drwxr-xr-x 2 root root 4096 ott 25 09:45 initramfs-tools
drwxr-xr-x 2 root root 4096 ott 12 12:44 iscan
drwxr-xr-x 2 root root 4096 ott 12 12:44 iscan-data
drwxr-xr-x 2 root root 4096 lug 25 05:06 ispell
drwxr-xr-x 3 root root 4096 lug 25 05:07 libxml-sax-perl
drwxr-xr-x 3 root root 4096 lug 25 05:10 locales
drwxr-xr-x 2 root root 4096 ott 30 00:07 logrotate
drwxr-xr-x 2 root root 4096 lug 25 05:08 man-db
drwxr-xr-x 2 root root 4096 apr 24 2018 misc
drwxr-xr-x 2 root root 4096 ott 30 00:08 mlocate
drwxr-xr-x 2 root root 4096 ott 30 06:46 NetworkManager
drwxr-xr-x 2 root root 4096 ott 25 09:45 os-prober
drwxr-xr-x 2 root root 4096 ott 30 09:52 PackageKit
drwxr-xr-x 2 root root 4096 lug 25 05:08 pam
drwxr-xr-x 2 root root 4096 set 1 00:05 plymouth
drwx------ 3 root root 4096 lug 25 05:04 polkit-1
drwx------ 3 root root 4096 set 1 00:05 private
drwxr-xr-x 2 root root 4096 set 1 11:41 python
drwxr-xr-x 3 root root 4096 ott 27 23:36 samba
drwxr-xr-x 19 root root 4096 ott 30 06:32 snapd
drwxr-xr-x 2 root root 4096 feb 20 2018 snmp
drwxr-xr-x 3 root root 4096 lug 25 05:04 sudo
drwxr-xr-x 9 root root 4096 set 22 11:49 systemd
drwxr-xr-x 2 root root 4096 set 1 00:00 ubiquity
drwxr-xr-x 2 root root 4096 set 1 00:05 ubuntu-drivers-common
drwxr-xr-x 2 root root 4096 ott 22 00:14 ubuntu-release-upgrader
drwxr-xr-x 3 root root 4096 ott 27 23:34 ucf
drwx------ 2 root root 4096 ott 29 09:58 udisks2
drwxr-xr-x 2 root root 4096 set 1 00:15 update-manager
drwxr-xr-x 4 root root 4096 ott 30 09:24 update-notifier
drwxr-xr-x 2 root root 4096 ott 29 10:07 upower
drwxr-xr-x 3 root root 4096 ott 25 22:00 ureadahead
drwxr-xr-x 2 root root 4096 mar 6 2018 usb_modeswitch
drwxr-xr-x 2 root root 4096 lug 25 05:05 usbutils
drwxr-xr-x 3 root root 4096 lug 25 05:04 vim
drwxr-xr-x 2 root root 4096 ott 29 10:57 whoopsie
drwxr-xr-x 2 root root 4096 lug 25 05:09 xfonts
drwxr-xr-x 2 root root 4096 ott 28 11:22 xkb
/var/lib/gdm3/:
total 96
drwxr-xr-x 6 gdm gdm 4096 ott 29 10:57 .
drwxr-xr-x 68 root root 4096 ott 27 23:33 ..
drwxr-xr-x 7 gdm gdm 4096 set 1 12:09 .cache
drwxr-xr-x 7 gdm gdm 4096 set 5 11:49 .config
drwx------ 3 gdm gdm 4096 set 1 00:05 .gnupg
-rw-r--r-- 1 root root 4339 ott 25 20:35 greeter-dconf-defaults
-rw------- 1 gdm gdm 57810 ott 29 10:57 .ICEauthority
drwx------ 3 gdm gdm 4096 set 1 00:05 .local
/var/lib/gdm3/.local/:
total 12
drwx------ 3 gdm gdm 4096 set 1 00:05 .
drwxr-xr-x 6 gdm gdm 4096 ott 29 10:57 ..
drwx------ 8 gdm gdm 4096 set 25 23:50 share
/var/lib/gdm3/.local/share/:
total 36
drwx------ 8 gdm gdm 4096 set 25 23:50 .
drwx------ 3 gdm gdm 4096 set 1 00:05 ..
drwx------ 2 gdm gdm 4096 set 1 00:05 gnome-shell
drwxrwxr-x 2 gdm gdm 4096 set 1 00:05 ibus-table
drwxrwxr-x 2 gdm gdm 4096 set 25 23:50 icc
drwx------ 2 gdm gdm 4096 set 1 00:05 keyrings
-rw-rw-r-- 1 gdm gdm 100 set 1 00:05 'session_migration-(null)'
drwx------ 2 gdm gdm 4096 set 1 00:05 sounds
drwx------ 2 gdm gdm 4096 ott 2 21:49 xorg
/var/lib/gdm3/.local/share/icc/:
total 16
drwxrwxr-x 2 gdm gdm 4096 set 25 23:50 .
drwx------ 8 gdm gdm 4096 set 25 23:50 ..
-rw-rw-r-- 1 gdm gdm 1420 set 1 00:05 edid-c16ba004ffc69e8889a4dfc31cb00abb.icc
-rw-rw-r-- 1 gdm gdm 1480 set 25 23:50 edid-d5eee630e5f2d664cb0b2b2b513fc95a.icc