通过cups打印文档后，/var/log/cups/access_log包含以下日志条目（并且打印机确实打印了）：
"POST /printers/Brother HTTP/1.1" 200 70947 Print-Job successful-ok
但是，通过lpstat查询时未列出打印作业：
# lpstat -W all -u user
# lpstat -v
device for Brother: ipp://printer.test.:631/ipp/port
为什么lpstat没有显示成功执行的打印作业？
每次由于域不存在（例如could not resolve host）而应该收到错误时，我都会收到有关连接到环回地址的错误：
$ curl -4 -v https://nonexist.invalid
Trying 127.0.0.1...
该问题仅在建立无线连接约 2 秒后才开始出现。短时间内，一切都按预期工作。
我正在使用systemd-resolved并且 dns 似乎正在工作：
$ readlink /etc/resolv.conf
../run/systemd/resolve/stub-resolve.conf
$ dig +short A example.com
192.0.2.1
$ dig +short A nonexist.invalid
$ systemd-resolve -t A nonexist.invalid
nonexist.invalid: resolve call failed: No appropriate name servers or networks for name found
如果名称解析看起来不错，为什么程序似乎仍将名称解析为127.0.0.1？
我想在qemu中运行 Ubuntu 安装程序。我使用了各自 Ubuntu CD 映像中的内核，并使用 AMD64 架构验证了我的命令行：
$ qemu-system-x86_64 --version
QEMU emulator version 2.5.0 ..
$ isoinfo -R -x "/install/vmlinuz" -i bionic-server-amd64.iso >linux
$ qemu-system-x86_64 -nodefaults -nographic -kernel linux \
-serial stdio -append "console=ttyS0" \
-machine pc -cpu qemu64 -m 1G
[ 0.0000000] Linux version 4.15.0-44-generic ..
但是，当我为 ARM64 架构（不是我的主机架构）尝试同样的事情时：
$ qemu-system-aarch64 --version
QEMU emulator version 2.5.0 ..
$ isoinfo -R -x "/install/vmlinuz" -i bionic-server-arm64.iso >linux
$ qemu-system-aarch64 -nodefaults -nographic -kernel linux \
-serial stdio -append "console=ttyAMA0" \
-machine virt -cpu cortex-a53 -m 1G
我在 100% cpu 使用时得到零输出。我如何确定出了什么问题？
执行-d unimp -D debug.log显示：
read access to unsupported AArch64 system register op0:3 op1:0 crn:0 crm:7 op2:2
有两个/usr/lib/libreoffice/share/registry/*.xcd设置，每个都应该足够：
org.openoffice.Office.Misc/Security/Scripting/DisableMacroExecution=true
org.openoffice.Office.Misc/Security/Scripting/MacroSecurityLevel=3
应用这些后，加载的文本文档中的宏会导致：
An attempt was made to execute a macro.
For security reasons, macro support is disabled.
但是，宏支持并未禁用。添加一个包含shell "xterm"到当前文档的宏并执行它仍然会显示一个终端窗口。
哪些选项真正禁用宏功能？
有没有办法不安装该功能，而不是尝试禁用它？
在使用 light-locker 锁定我的屏幕后，一台带有新创建用户的 Xubuntu 16.04 完全修补的机器不会让我解锁（无论锁定是手动激活还是通过超时激活）。正确输入密码后屏幕保持黑色（但已通电）
从 tty1 中杀死 light-locker 将随后显示桌面（并因此防止进一步锁定）。
尝试的步骤：
This session is locked: You will be redirected to the unlock dialog automatically in a few seconds消息 - 没有任何重定向发生loginctl unlock-session没有效果systemctl status lightdm仅显示有关 kwallet pam 模块丢失的（无害的，预期的）消息nopasswdlogin组（锁定后立即出现黑屏，不仅在输入密码后）在弄清楚如何解决这个问题时，哪些额外的步骤可以证明是有用的？
调试日志：
$ export LC_ALL=C; light-locker --debug & ( sleep 5; echo "## Locking now"; light-locker-command --lock; sleep 10; echo "### 10 seconds have passed - entering password now"; sleep 10; echo "### 10 more seconds have passwd - Killing"; killall light-locker; sleep 5; echo "### Killed now" )
[1] 23463
[gs_debug_init] gs-debug.c:106 (00:08:32): Debugging enabled
[main] light-locker.c:142 (00:08:32): initializing light-locker 1.7.0
[main] light-locker.c:144 (00:08:32): lock after screensaver 10
[main] light-locker.c:145 (00:08:32): late locking 0
[main] light-locker.c:146 (00:08:32): lock on suspend 1
[main] light-locker.c:147 (00:08:32): lock on lid 0
[main] light-locker.c:148 (00:08:32): idle hint 1
[query_session_id] gs-listener-dbus.c:2088 (00:08:32): org.freedesktop.login1.NoSessionForPID raised:
PID 23463 does not belong to any known session
[init_session_id] gs-listener-dbus.c:2180 (00:08:32): Got session-id: (null)
[query_sd_session_id] gs-listener-dbus.c:2164 (00:08:32): Couldn't determine our own sd session id: No such process
[init_session_id] gs-listener-dbus.c:2185 (00:08:32): Got sd-session-id: (null)
[init_seat_path] gs-listener-dbus.c:2262 (00:08:32): Got seat: /org/freedesktop/DisplayManager/Seat0
[gs_listener_delay_suspend] gs-listener-dbus.c:449 (00:08:32): Delay suspend
[gs_listener_x11_acquire] gs-listener-x11.c:172 (00:08:32): ScreenSaver Registered
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:32): obj_path=/org/freedesktop/DBus interface=org.freedesktop.DBus method=NameAcquired destination=:1.316
## Locking now
[gs_grab_grab_root] gs-grab-x11.c:647 (00:08:37): Grabbing the root window
[gs_grab_get_keyboard] gs-grab-x11.c:153 (00:08:37): Grabbing keyboard widget=E3
[gs_grab_get_mouse] gs-grab-x11.c:213 (00:08:37): Grabbing mouse widget=E3
[gs_manager_create_windows_for_screen] gs-manager.c:548 (00:08:37): Creating 1 windows for screen 0
[gs_manager_create_window_for_monitor] gs-manager.c:324 (00:08:37): Creating window for monitor 0 [0,0] (1600x900)
[update_geometry] gs-window-x11.c:197 (00:08:37): got geometry for monitor 0: x=0 y=0 w=1600 h=900
[update_geometry] gs-window-x11.c:210 (00:08:37): using geometry for monitor 0: x=0 y=0 w=1600 h=900
[update_geometry] gs-window-x11.c:197 (00:08:37): got geometry for monitor 0: x=0 y=0 w=1600 h=900
[update_geometry] gs-window-x11.c:210 (00:08:37): using geometry for monitor 0: x=0 y=0 w=1600 h=900
[gs_window_move_resize_window] gs-window-x11.c:243 (00:08:37): Move and/or resize window on monitor 0: x=0 y=0 w=1600 h=900
[update_geometry] gs-window-x11.c:197 (00:08:37): got geometry for monitor 0: x=0 y=0 w=1600 h=900
[update_geometry] gs-window-x11.c:210 (00:08:37): using geometry for monitor 0: x=0 y=0 w=1600 h=900
[gs_window_move_resize_window] gs-window-x11.c:243 (00:08:37): Move and/or resize window on monitor 0: x=0 y=0 w=1600 h=900
[update_geometry] gs-window-x11.c:197 (00:08:37): got geometry for monitor 0: x=0 y=0 w=1600 h=900
[update_geometry] gs-window-x11.c:210 (00:08:37): using geometry for monitor 0: x=0 y=0 w=1600 h=900
[gs_window_move_resize_window] gs-window-x11.c:243 (00:08:37): Move and/or resize window on monitor 0: x=0 y=0 w=1600 h=900
[gs_manager_timed_switch] gs-manager.c:445 (00:08:37): Start switch to greeter timer
[gs_window_xevent] gs-window-x11.c:369 (00:08:37): not raising our windows
[window_map_event_cb] gs-manager.c:233 (00:08:37): Handling window map_event event
[gs_listener_resume_suspend] gs-listener-dbus.c:513 (00:08:37): Resume suspend: fd=14
[manager_maybe_grab_window] gs-manager.c:204 (00:08:37): Moving grab to 0x5595f8d5a290
[gs_grab_move_keyboard] gs-grab-x11.c:450 (00:08:37): Moving keyboard grab from E3 to 3A0000C
[gs_grab_move_keyboard] gs-grab-x11.c:457 (00:08:37): *** doing X server grab
[gs_grab_release_keyboard] gs-grab-x11.c:279 (00:08:37): Ungrabbing keyboard
[gs_grab_get_keyboard] gs-grab-x11.c:153 (00:08:37): Grabbing keyboard widget=3A0000C
[gs_grab_move_keyboard] gs-grab-x11.c:479 (00:08:37): *** releasing X server grab
[gs_grab_move_mouse] gs-grab-x11.c:395 (00:08:37): Moving pointer grab from E3 to 3A0000C
[gs_grab_move_mouse] gs-grab-x11.c:402 (00:08:37): *** doing X server grab
[gs_grab_release_mouse] gs-grab-x11.c:320 (00:08:37): Ungrabbing pointer
[gs_grab_get_mouse] gs-grab-x11.c:213 (00:08:37): Grabbing mouse widget=3A0000C
[gs_grab_move_mouse] gs-grab-x11.c:425 (00:08:37): *** releasing X server grab
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:37): obj_path=/org/freedesktop/login1 interface=org.freedesktop.DBus.Properties method=PropertiesChanged destination=(null)
[update_geometry] gs-window-x11.c:197 (00:08:37): got geometry for monitor 0: x=0 y=0 w=1600 h=900
[update_geometry] gs-window-x11.c:210 (00:08:37): using geometry for monitor 0: x=0 y=0 w=1600 h=900
[gs_window_move_resize_window] gs-window-x11.c:243 (00:08:37): Move and/or resize window on monitor 0: x=0 y=0 w=1600 h=900
[update_geometry] gs-window-x11.c:197 (00:08:37): got geometry for monitor 0: x=0 y=0 w=1600 h=900
[update_geometry] gs-window-x11.c:210 (00:08:37): using geometry for monitor 0: x=0 y=0 w=1600 h=900
[gs_window_move_resize_window] gs-window-x11.c:243 (00:08:37): Move and/or resize window on monitor 0: x=0 y=0 w=1600 h=900
[gs_listener_send_lock_session] gs-listener-dbus.c:180 (00:08:38): Send lock session
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:38): obj_path=(null) interface=(null) method=(null) destination=:1.316
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:39): obj_path=/org/freedesktop/login1/session/c5 interface=org.freedesktop.DBus.Properties method=PropertiesChanged destination=(null)
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:39): obj_path=/org/freedesktop/login1/session/c12 interface=org.freedesktop.DBus.Properties method=PropertiesChanged destination=(null)
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:39): obj_path=/org/freedesktop/login1/seat/seat0 interface=org.freedesktop.DBus.Properties method=PropertiesChanged destination=(null)
process 23463: arguments to dbus_message_new_method_call() were incorrect, assertion "path != NULL" failed in file ../../dbus/dbus-message.c line 1340.
This is normally a bug in some application using the D-Bus library.
[query_session_active] gs-listener-dbus.c:1124 (00:08:39): Couldn't allocate the dbus message
[listener_dbus_handle_system_message] gs-listener-dbus.c:1361 (00:08:39): systemd notified ActiveSession 0
[listener_session_switched_cb] gs-monitor.c:298 (00:08:39): Session switched: 0
[gs_manager_stop_switch] gs-manager.c:456 (00:08:39): Stop switch to greeter timer
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:39): obj_path=/org/freedesktop/login1/seat/seat0 interface=org.freedesktop.DBus.Properties method=PropertiesChanged destination=(null)
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:39): obj_path=/org/freedesktop/login1/session/c12 interface=org.freedesktop.DBus.Properties method=PropertiesChanged destination=(null)
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:39): obj_path=/org/freedesktop/login1/user/_108 interface=org.freedesktop.DBus.Properties method=PropertiesChanged destination=(null)
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:39): obj_path=/org/freedesktop/login1/seat/seat0 interface=org.freedesktop.DBus.Properties method=PropertiesChanged destination=(null)
process 23463: arguments to dbus_message_new_method_call() were incorrect, assertion "path != NULL" failed in file ../../dbus/dbus-message.c line 1340.
This is normally a bug in some application using the D-Bus library.
[query_session_active] gs-listener-dbus.c:1124 (00:08:39): Couldn't allocate the dbus message
[listener_dbus_handle_system_message] gs-listener-dbus.c:1361 (00:08:39): systemd notified ActiveSession 0
[listener_session_switched_cb] gs-monitor.c:298 (00:08:39): Session switched: 0
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:39): obj_path=/org/freedesktop/login1/session/c5 interface=org.freedesktop.login1.Session method=Lock destination=(null)
### 10 seconds have passed - entering password now
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:51): obj_path=/org/freedesktop/login1/session/c5 interface=org.freedesktop.login1.Session method=Unlock destination=(null)
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:51): obj_path=/org/freedesktop/login1/session/c13 interface=org.freedesktop.DBus.Properties method=PropertiesChanged destination=(null)
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:51): obj_path=/org/freedesktop/login1/session/c5 interface=org.freedesktop.DBus.Properties method=PropertiesChanged destination=(null)
[listener_dbus_handle_system_message] gs-listener-dbus.c:1330 (00:08:51): obj_path=/org/freedesktop/login1/seat/seat0 interface=org.freedesktop.DBus.Properties method=PropertiesChanged destination=(null)
process 23463: arguments to dbus_message_new_method_call() were incorrect, assertion "path != NULL" failed in file ../../dbus/dbus-message.c line 1340.
This is normally a bug in some application using the D-Bus library.
[query_session_active] gs-listener-dbus.c:1124 (00:08:51): Couldn't allocate the dbus message
[listener_dbus_handle_system_message] gs-listener-dbus.c:1361 (00:08:51): systemd notified ActiveSession 0
[listener_session_switched_cb] gs-monitor.c:298 (00:08:51): Session switched: 0
[xroot_filter] gs-listener-x11.c:124 (00:08:52): ScreenSaver stopped
### 10 more seconds have passwd - Killing
### Killed now
将此与已知良好的系统进行比较会产生：
$ comm -3 <(grep -iv grab good | sed 's/[0-9:]\+/[NN]/g;s/[ \t]\+/ /g' | sort) <(grep -iv grab bad | sed 's/[0-9:]\+/[NN]/g;s/[ \t]\+/ /g' | sort) | head -n2
[init_session_id] gs-listener-dbus.c[NN] ([NN])[NN] Got session-id[NN] (null)
[init_session_id] gs-listener-dbus.c[NN] ([NN])[NN] Got session-id[NN] /org/freedesktop/login[NN]/session/c[NN]
事实上，会话设置似乎很尴尬：
$ loginctl session-status
Could not get properties: No such process
我将我的 Ubuntu 14.04 和 16.04 笔记本用于开发目的，并定期在无法从 Internet 访问的网络地址上运行各种服务器（例如 Web 服务器）。
如果有人将他的域名重新绑定到私有 IP，我如何避免仍然通过我的网络浏览器向世界公开这些服务器？
尝试调整未使用 64 位标志创建的旧 ext4 分区的大小时，如果新大小为或超过 16TiB，resize2fs 1.42 将失败。
$ resize2fs -p /dev/mapper/target-device
resize2fs: New size too large to be expressed in 32 bits
我不想将文件复制到外部介质。我也不想冒数据丢失的风险。如何安全地调整音量？
我正在尝试在 14.04.2 LTS 上调试一个不成功/挂起的系统启动（upstart）。root 是 luks 容器中的 ext4 文件系统。文件系统处于干净状态。
引导过程在 upstart-socket-bridge 之后停止，（不一定在特定服务之后，例如，当安装 cups-daemon 时，它会在那之后停止）。init -v也不是很有帮助。唯一不仅仅记录各种服务的启动/停止的日志条目是关于 init 之前的 udev。
Begin: Running /scripts/init-bottom ... done.
udev exit failed --rc=2
（编辑）重新挂载 root rw 最初似乎总是导致干净启动，但事实是，它有点不可预测，无论哪种方式，我都失败并成功启动。哇？
观察：一切似乎都很好，系统只是没有重新挂载根可写或继续引导。
问：我如何确定是哪个服务导致启动过程卡住？
initctl list挂断后可以运行，这些是正在运行的作业mountnfs-bootclean.sh start/running
udev start/running, process 438
upstart-udev-bridge start/running, process 432
plymouth start/running, process 122
resolvconf start/running
ssh start/running, process 767 <-- this one was manually started
mountall start/running, process 337
mountkernfs.sh start/running
mountnfs.sh start/running
bootmisc.sh start/running
upstart-socket-bridge start/running, process 745**
cryptdisks start/running
mountdevsubfs.sh start/running
mtab.sh start/running
network-interface (lo) start/running
network-interface (eth0) start/running
plymouth-ready (startup) start/running, process 315
plymouth-upstart-bridge start/running, process 316
mountall-bootclean.sh start/running
network-interface-security (network-interface/eth0) start/running
network-interface-security (network-interface/lo) start/running
init 5让卡住的系统继续正常启动。看来是ureadaheads的错。清除它导致 5 个干净的靴子没有任何问题。我将把这个问题（和 100 个额外的代表）留给任何有兴趣或知道原始问题答案的人：如果不是通过随机试验，我怎么能弄清楚这个问题。