Drew Noakes's questions

For the last few days, certain desktop applications have started dying whenever the Ctrl, Alt or Shift keys are pressed, or the GUI is right-clicked. This happens on keydown/mousedown.

For example, it happens in:

• Nautilus
• Update Manager
• Rhythmbox Music Player
• Gnome Screenshot
• Gedit (only seems to crash on right-click and some keystrokes such as Ctrl+S)

It does not happen in all applications. For example, Chrome, Clion (IDE), Skype, gitk are unaffected.

If I launch nautilus from the command line, then press Ctrl:

$ nautilus
Segmentation fault

Running it with gdb shows the following backtrace:

#0  0x0000000000000000 in ?? ()
#1  0x00007ffff474a1c8 in g_closure_invoke () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#2  0x00007ffff475abe7 in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#3  0x00007ffff4763098 in g_signal_emit_valist () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#4  0x00007ffff4763352 in g_signal_emit () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#5  0x00007ffff6ea616b in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#6  0x00007ffff6f1b095 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#7  0x00007ffff6ea61d2 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#8  0x00007ffff6dbc027 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#9  0x00007ffff6ea61d2 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#10 0x00007ffff6ee20a1 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#11 0x00007ffff6ea61d2 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#12 0x00007ffff6e68fd0 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#13 0x00007ffff6ea61d2 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#14 0x00007ffff6fe2d49 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#15 0x00007ffff6ea61d2 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#16 0x00007ffff6ea62ab in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#17 0x00007ffff6fe9233 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#18 0x00007ffff474a1c8 in g_closure_invoke () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#19 0x00007ffff475abe7 in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#20 0x00007ffff4763098 in g_signal_emit_valist () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#21 0x00007ffff4763352 in g_signal_emit () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#22 0x00007ffff6fd895c in gtk_widget_show () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#23 0x000000000047563c in ?? ()
#24 0x0000000000479871 in ?? ()
#25 0x00007ffff6ea818e in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#26 0x00007ffff474a3f7 in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#27 0x00007ffff4762708 in g_signal_emit_valist () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#28 0x00007ffff4763352 in g_signal_emit () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#29 0x00007ffff6fcee5c in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#30 0x00007ffff6ea5cf8 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#31 0x00007ffff6ea76f7 in gtk_main_do_event () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#32 0x00007ffff6a5bc22 in ?? () from /usr/lib/x86_64-linux-gnu/libgdk-3.so.0
#33 0x00007ffff4476bd4 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#34 0x00007ffff4476e18 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#35 0x00007ffff4476ebc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#36 0x00007ffff4a2e0bc in g_application_run () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#37 0x000000000042b561 in ?? ()
#38 0x00007ffff394aec5 in __libc_start_main (main=0x42b4a0, argc=0x1, argv=0x7fffffffdf98, init=<optimised out>, fini=<optimised out>, rtld_fini=<optimised out>, stack_end=0x7fffffffdf88) at libc-start.c:287
#39 0x000000000042b5c3 in ?? ()

I've noticed that nautilus looks different since this started happening:

Any ideas how I can fix this?

$ uname -a
Linux bert 3.13.0-44-generic #73-Ubuntu SMP Tue Dec 16 00:22:43 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 14.04.1 LTS
Release:    14.04
Codename:   trusty

The contents of /etc/apt/sources.list are:

deb http://gb.archive.ubuntu.com/ubuntu/ trusty main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu/ trusty-security main restricted universe multiverse
deb http://gb.archive.ubuntu.com/ubuntu/ trusty-updates main restricted universe multiverse
# deb http://archive.canonical.com/ lucid partner
deb-src http://archive.canonical.com/ lucid partner
# deb http://ppa.launchpad/gnurubuntu/rubuntu/ubuntu raring main
# deb-src http://ppa.launchpad/gnurubuntu/rubuntu/ubuntu raring main
# deb-src http://repos.codelite.org/ubuntu/ raring universe

How can I write an entry into /var/log/syslog from the command line?

There are several questions and answers on askubuntu about seeing disk space from the command line.

Naturally, df is the go-to tool for this.

However I want a script at login to raise an alert if the free disk space is below some threshold.

Unfortunately df seems to use arbitrarily sized columns and I'm not sure how to extract just the value from the column I'm interested in.

For example:

$ df /dev/mapper/root
Filesystem       1K-blocks    Used Available Use% Mounted on
/dev/mapper/root   2563092 1649968    763212  69% /
$ df /dev/mapper/root | tail -n 1
/dev/mapper/root   2563092 1649968    763212  69% /
$ df /dev/mapper/root | tail -n 1 | cut -d ' ' -f 9
763212

Really I want the fourth column, yet I must ask for the ninth.

Is there an easier way to either extract the column's value from df's output, or another way altogether to access this value.

I'm working with a robotic platform (for use in the RoboCup competition) and we run Ubuntu Server 13.10. It's critical during matches that our robots are able to boot as quickly as possible. What's more, if they power cycles during a fall, then the robot has 10 seconds to come back to life before being taken off the field.

Currently the boot time is around 15 seconds and I'd like to know what I can do to reduce that time. Hopefully I can learn something too.

Here is the full output of dmesg which I suppose helps break down what is going on at each time step. There are a few gaps in the output:

• At 0.41 there's a gap of about 0.8 seconds
• At 3.64 there's a gap of about 2.8 seconds
• At 9.67 there's a gap of about 0.8 seconds
• At 12.9 there's a gap of about 1.4 seconds

eth is not required though wlan is.

Can anyone decode this into actionable advice for how to get this bot booted faster? And if there is not enough information in these messages, what else might I try to investigate further?

EDIT I modified my binary (which starts automatically as an upstart job) to write to the syslog. It shows, starting with the first logged message after powered:

Oct 30 12:51:52 darwin6 kernel: imklog 5.8.11, log source = /proc/kmsg started.
....
Oct 30 12:52:12 darwin6 kernel: [   34.276716] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
Oct 30 12:52:13 darwin6 dhclient: Internet Systems Consortium DHCP Client 4.2.4
Oct 30 12:52:13 darwin6 dhclient: Copyright 2004-2012 Internet Systems Consortium.
Oct 30 12:52:13 darwin6 dhclient: All rights reserved.
Oct 30 12:52:13 darwin6 dhclient: For info, please visit https://www.isc.org/software/dhcp/
Oct 30 12:52:13 darwin6 dhclient: 
Oct 30 12:52:13 darwin6 dhclient: Listening on LPF/wlan0/00:0d:f0:95:0d:4d
Oct 30 12:52:13 darwin6 dhclient: Sending on   LPF/wlan0/00:0d:f0:95:0d:4d
Oct 30 12:52:13 darwin6 dhclient: Sending on   Socket/fallback
Oct 30 12:52:13 darwin6 dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 3 (xid=0x3cd422f3)
Oct 30 12:52:13 darwin6 dhclient: DHCPREQUEST of 192.168.0.3 on wlan0 to 255.255.255.255 port 67 (xid=0x3cd422f3)
Oct 30 12:52:13 darwin6 dhclient: DHCPOFFER of 192.168.0.3 from 192.168.0.1
Oct 30 12:52:13 darwin6 avahi-daemon[833]: Joining mDNS multicast group on interface wlan0.IPv6 with address fe80::20d:f0ff:fe95:d4d.
Oct 30 12:52:13 darwin6 avahi-daemon[833]: New relevant interface wlan0.IPv6 for mDNS.
Oct 30 12:52:13 darwin6 avahi-daemon[833]: Registering new address record for fe80::20d:f0ff:fe95:d4d on wlan0.*.
Oct 30 12:52:14 darwin6 dhclient: DHCPACK of 192.168.0.3 from 192.168.0.1
Oct 30 12:52:14 darwin6 avahi-daemon[833]: Joining mDNS multicast group on interface wlan0.IPv4 with address 192.168.0.3.
Oct 30 12:52:14 darwin6 avahi-daemon[833]: New relevant interface wlan0.IPv4 for mDNS.
Oct 30 12:52:14 darwin6 avahi-daemon[833]: Registering new address record for 192.168.0.3 on wlan0.IPv4.
Oct 30 12:52:14 darwin6 dhclient: bound to 192.168.0.3 -- renewal in 41314 seconds.
Oct 30 12:52:21 darwin6 ntpdate[1294]: adjust time server 91.189.94.4 offset -0.243167 sec
Oct 30 12:52:46 darwin6 kernel: [   68.451644] perf samples too long (2504 > 2500), lowering kernel.perf_event_max_sample_rate to 50000
Oct 30 12:53:49 darwin6 boldhumanoid[1455]: Starting boldhumanoid process

The strange thing is that I also timed with a stopwatch. From turning the power on to my process starting (the robot coming alive) was 35 seconds. It seems that something is causing the syslog write to be delayed by a further 100 seconds, going by the timestamps.

I bought a new SD card and the claimed performance is a long way from my benchmark. Is there something I can do improve the transfer speed when working with this SD card?

Information on the disk:

$ df --output=source,fstype,size,target -h
Filesystem     Type      Size Mounted on
/dev/mmcblk0p1 fuseblk    60G /media/drew/6564-6433

Partition type: HPFS/NTFS
Contents:       exFAT (version 1.0)

The card's packaging claims:

Speed up to 30 MB/s* (200X)

Following the asterisk leads to:

Up to 30MB/s transfer speed; write speed lower. Based on internal testing; performance may be lower depending on host device. 1MP = 1,000,000 bytes. X = 150KB/s.

My machine didn't recognise the card's formatting at first, so I installed exfat-fuse the package and it worked at the next attempt.

I then ran a benchmark using gnome-disks:

As you can see, the average read speed of 7.1 MB/s which is a long way from 30 MB/s. That's 4.2 times slower (23%).

Is there anything I can do to improve the transfer speed when working with this SD card?

EDIT output of hdparam as requested in comments:

$ sudo hdparm -tT /dev/mmcblk0

/dev/mmcblk0:
 Timing cached reads:   12186 MB in  1.99 seconds = 6111.71 MB/sec
 Timing buffered disk reads:  34 MB in  3.17 seconds =  10.73 MB/sec

I executed this four times on an unoccupied machine and the results were consistent across runs.

The first number (6GB/s) is described as:

the speed of reading directly from the Linux buffer cache without disk access. This measurement is essentially an indication of the throughput of the processor, cache, and memory of the system under test.

The second number (10 MB/s) is described as:

This displays the speed of reading through the buffer cache to the disk without any prior caching of data. This measurement is an indication of how fast the drive can sustain sequential data reads under Linux, without any filesystem overhead.

So 10 MB/s may be the throughput for a different type of load, or possibly just for a shorter time (the incomplete chart above ran for around 5 minutes before I took that screenshot.) Either way, it's still not close to 30 MB/s!

After rebuilding a machine with a fresh install of 13.10 Server, I see the following errors when trying to run wicd-curses:

$ wicd-curses 
Can't connect to the daemon, trying to start it automatically...
Traceback (most recent call last):
  File "/usr/share/wicd/curses/wicd-curses.py", line 1043, in <module>
    setup_dbus()
  File "/usr/share/wicd/curses/wicd-curses.py", line 1031, in setup_dbus
    dbus_ifaces = dbusmanager.get_dbus_ifaces()
  File "/usr/lib/python2.7/dist-packages/wicd/dbusmanager.py", line 36, in get_dbus_ifaces
    return DBUS_MANAGER.get_dbus_ifaces()
  File "/usr/lib/python2.7/dist-packages/wicd/dbusmanager.py", line 62, in get_dbus_ifaces
    if not self._dbus_ifaces: connect_to_dbus()
  File "/usr/lib/python2.7/dist-packages/wicd/dbusmanager.py", line 48, in connect_to_dbus
    return DBUS_MANAGER.connect_to_dbus()
  File "/usr/lib/python2.7/dist-packages/wicd/dbusmanager.py", line 79, in connect_to_dbus
    proxy_obj = self._bus.get_object("org.wicd.daemon", '/org/wicd/daemon')
  File "/usr/lib/python2.7/dist-packages/dbus/bus.py", line 241, in get_object
    follow_name_owner_changes=follow_name_owner_changes)
  File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 248, in __init__
    self._named_service = conn.activate_name_owner(bus_name)
  File "/usr/lib/python2.7/dist-packages/dbus/bus.py", line 180, in activate_name_owner
    self.start_service_by_name(bus_name)
  File "/usr/lib/python2.7/dist-packages/dbus/bus.py", line 278, in start_service_by_name
    'su', (bus_name, flags)))
  File "/usr/lib/python2.7/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.ServiceUnknown: The name org.wicd.daemon was not provided by any .service files
Error in sys.excepthook:
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/apport_python_hook.py", line 96, in apport_excepthook
    dbus_service_unknown_analysis(exc_obj, pr)
  File "/usr/lib/python2.7/dist-packages/apport_python_hook.py", line 172, in dbus_service_unknown_analysis
    cp = ConfigParser(interpolation=None)
TypeError: __init__() got an unexpected keyword argument 'interpolation'

Original exception was:
Traceback (most recent call last):
  File "/usr/share/wicd/curses/wicd-curses.py", line 1043, in <module>
    setup_dbus()
  File "/usr/share/wicd/curses/wicd-curses.py", line 1031, in setup_dbus
    dbus_ifaces = dbusmanager.get_dbus_ifaces()
  File "/usr/lib/python2.7/dist-packages/wicd/dbusmanager.py", line 36, in get_dbus_ifaces
    return DBUS_MANAGER.get_dbus_ifaces()
  File "/usr/lib/python2.7/dist-packages/wicd/dbusmanager.py", line 62, in get_dbus_ifaces
    if not self._dbus_ifaces: connect_to_dbus()
  File "/usr/lib/python2.7/dist-packages/wicd/dbusmanager.py", line 48, in connect_to_dbus
    return DBUS_MANAGER.connect_to_dbus()
  File "/usr/lib/python2.7/dist-packages/wicd/dbusmanager.py", line 79, in connect_to_dbus
    proxy_obj = self._bus.get_object("org.wicd.daemon", '/org/wicd/daemon')
  File "/usr/lib/python2.7/dist-packages/dbus/bus.py", line 241, in get_object
    follow_name_owner_changes=follow_name_owner_changes)
  File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 248, in __init__
    self._named_service = conn.activate_name_owner(bus_name)
  File "/usr/lib/python2.7/dist-packages/dbus/bus.py", line 180, in activate_name_owner
    self.start_service_by_name(bus_name)
  File "/usr/lib/python2.7/dist-packages/dbus/bus.py", line 278, in start_service_by_name
    'su', (bus_name, flags)))
  File "/usr/lib/python2.7/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.ServiceUnknown: The name org.wicd.daemon was not provided by any .service files

It seems that wicd is not running. pgrep wicd returns no results.

Attempting to start it fails:

$ sudo /etc/init.d/wicd start
 * Starting Network connection manager wicd          [fail]

If I attempt to run wicd directly, I see:

$ sudo wicd
Traceback (most recent call last):
  File "/usr/share/wicd/daemon/wicd-daemon.py", line 1859, in <module>
    main(sys.argv)
  File "/usr/share/wicd/daemon/wicd-daemon.py", line 1708, in main
    os.symlink(dest, backup_location)
OSError: [Errno 17] File exists

Running wicd -foe gives the same output.

Exact package versions are:

python-wicd 1.7.2.4-4.1
wicd-curses 1.7.2.4-4.1
wicd-daemon 1.7.2.4-4.1

The /var/log/wicd/ directory is empty.

I tried reinstalling:

sudo apt-get remove wicd-curses
sudo apt-get autoremove
sudo rm -rf /etc/wicd
sudo rm -rf /var/log/wicd
sudo reboot now
sudo apt-get install wicd-curses

However this didn't help. During the installation:

Get:1 http://gb.archive.ubuntu.com/ubuntu/ saucy/main python-gobject all 3.10.0-1ubuntu1 [2,476 B]
Get:2 http://gb.archive.ubuntu.com/ubuntu/ saucy/universe python-wicd all 1.7.2.4-4.1 [39.3 kB]
Get:3 http://gb.archive.ubuntu.com/ubuntu/ saucy/universe wicd-daemon all 1.7.2.4-4.1 [217 kB]
Get:4 http://gb.archive.ubuntu.com/ubuntu/ saucy/universe python-urwid i386 1.1.1-1 [662 kB]
Get:5 http://gb.archive.ubuntu.com/ubuntu/ saucy/main rfkill i386 0.4-2ubuntu1 [9,160 B]
Get:6 http://gb.archive.ubuntu.com/ubuntu/ saucy/universe wicd-curses all 1.7.2.4-4.1 [35.0 kB]
Fetched 964 kB in 0s (1,234 kB/s)      
Preconfiguring packages ...
Selecting previously unselected package python-gobject.
(Reading database ... 60265 files and directories currently installed.)
Unpacking python-gobject (from .../python-gobject_3.10.0-1ubuntu1_all.deb) ...
Selecting previously unselected package python-wicd.
Unpacking python-wicd (from .../python-wicd_1.7.2.4-4.1_all.deb) ...
Selecting previously unselected package wicd-daemon.
Unpacking wicd-daemon (from .../wicd-daemon_1.7.2.4-4.1_all.deb) ...
Selecting previously unselected package python-urwid.
Unpacking python-urwid (from .../python-urwid_1.1.1-1_i386.deb) ...
Selecting previously unselected package rfkill.
Unpacking rfkill (from .../rfkill_0.4-2ubuntu1_i386.deb) ...
Selecting previously unselected package wicd-curses.
Unpacking wicd-curses (from .../wicd-curses_1.7.2.4-4.1_all.deb) ...
Processing triggers for man-db ...
Processing triggers for ureadahead ...
ureadahead will be reprofiled on next reboot
Setting up python-gobject (3.10.0-1ubuntu1) ...
Setting up python-wicd (1.7.2.4-4.1) ...
Setting up wicd-daemon (1.7.2.4-4.1) ...
 * Restarting Network connection manager wicd              [fail] 
Setting up python-urwid (1.1.1-1) ...
Setting up rfkill (0.4-2ubuntu1) ...
Setting up wicd-curses (1.7.2.4-4.1) ...

After this the failure is the behaviour is identical to that shown above.

Digging into the Python code a little shows where the problem is occurring. From line 1708 in /usr/share/wicd/daemon/wicd-daemon.py:

# back up resolv.conf before we do anything else
try:
    backup_location = wpath.varlib + 'resolv.conf.orig'
    # don't back up if .orig exists, probably there cause
    # wicd exploded
    if not os.path.exists(backup_location):
        if os.path.islink('/etc/resolv.conf'):
            dest = os.readlink('/etc/resolv.conf')
            os.symlink(dest, backup_location)                  <--- LINE 1708
        else:
            shutil.copy2('/etc/resolv.conf', backup_location)
        os.chmod(backup_location, 0644)
except IOError:
    print 'error backing up resolv.conf'

Debugging this code shows

dest            = ../run/resolvconf/resolv.conf
backup_location = /var/lib/wicd/resolv.conf.orig

I attempted changing the except block to catch both OSError and IOError. I now see the error message error backing up resolv.conf, however the daemon doesn't seem to start properly.

$ sudo wicd
error backing up resolv.conf
$ echo $?
0
$ ps -ef | grep "wi[c]d"

It seems that the .pid file was created and not deleted. Attempting to run wicd another time gives:

$ sudo wicd
error backing up resolv.conf
It seems like the daemon is already running.
If it is not, please remove /var/run/wicd/wicd.pid and try again.

It is not running. ps shows that, and wicd-curses gives the same error as above.

When running git status -sb I see:

I want to watch (from procps-ng 3.3.3) a repository. The --color option is supposed to keep colours.

Interestingly, it works with ls:

$ watch --color "ls --color"

Showing:

However for git the colours disappear:

$ watch --color "git status -sb"

So, why does watch show colours from ls but not from git output?

When logging in via SSH, I'd like to know, during the execution of .bashrc, the name of the host that is connecting.

Ubuntu Server shows the prompt:

Last login: Fri Feb 14 11:34:55 2014 from somehost.local

...so this information is available somewhere.

How can I access it?

When I log in, I see the error:

bash: alias: alias: not found

If I source my .bashrc file, the message appears again.

What is causing this?

My machine crashed with KDevelop running, and after rebooting it won't start, saying:

Failed to lock the session, probably it is already active in another running instance

However I definitely do not have it running anywhere.

How can I clear up whatever kind of lock it created and failed to clean up after itself?

I'm building a program in a VM then deploying to another machine. This has been working for some time.

Today I've started receiving this error message when I attempt to execute my program:

/usr/lib/i386-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.19' not found

Both machines are running the same kernel version, and all packages are up to date:

$ uname -a
Linux darwin7 3.8.0-23-generic #34-Ubuntu SMP Wed May 29 20:24:54 UTC 2013 i686 i686 i686 GNU/Linux

How might I investigate and repair this issue?

In Ubuntu 13.04, the Software Updater shows some apps as having updates, but they're non-selectable:

It's not clear why they're greyed out.

On the command line:

$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages have been kept back:
  gnuplot-nox gnuplot-x11 nvidia-current
0 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.

Note too that running apt-get dist-upgrade does not cause them to be installed either, as it sometimes does with packages that are kept back. Here's the output:

$ sudo apt-get dist-upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
The following packages have been kept back:
  gnuplot-nox gnuplot-x11 nvidia-current
0 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.

I took @quidage's suggestion, which gives the following. However subsequent upgrades show the same message:

$ sudo apt-get install -f
Reading package lists... Done
Building dependency tree       
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.

Sometimes when running ping, I see the following:

$ ping somehost
PING somehost (192.168.x.x) 56(84) bytes of data.
WARNING: kernel is not very fresh, upgrade is recommended

What causes this warning, and can I ignore it? I'm actually running a relatively new kernel (3.5.0-17-generic).

By normal brightness controls I mean the accelerators on my laptop's keyboard that seem to integrate with Unity.

In a dark room, my screen is quite bright, even on the lowest setting. Can I override this?

I tried setting it explicitly via both:

sudo echo 500 > /sys/class/backlight/acpi_video0/actual_brightness
sudo echo 500 > /sys/class/backlight/intel_backlight/actual_brightness

But I get a permission denied error.

When at the lower bounds via my keyboard's brighness controls, acpi_video0/actual_brightness is 0, and intel_backlight/actual_brightness is 729. Can I set the latter value to be even lower?

When attempting to run a remote binary using sudo on the remote box:

ssh remotehost "sudo ./binary"

I see this error:

sudo: no tty present and no askpass program specified

How can I work around this?

I'm using Wubi and want to share a directory from the (Win8) host via Samba. When I try to do this using Nautilus I receive the following error:

'net usershare' returned error 255: net usershare add: cannot share path /host/path as we are restricted to only sharing directories we own.

Ask the administrator to add the line "usershare owner only = false" to the [global] section of the smb.conf to allow this.

Are there any negative implications to adding this line?

I've just installed Samba on my Ubuntu 12.04 machine and need to access it from Windows Server 2008.

$ sudo apt-get install samba
$ service smbd status
smbd start/running, process 23485

When I try to connect from the Windows Run dialog using \\192.168.1.111 (verified using ifconfig) I see the error message:

\\192.168.1.111

The specified network name is no longer available

This error pops up immediately. Note that before installing smbd the error took a while to appear and was a generic cannot connect to host type error. If I stop smbd, then the response goes back to timing out, so I know there's connectivity between the boxes.

What does this mean and what can I do to resolve this?

Currently my o folder is appearing in my KDevelop project tree, and therefore .o files appear in the open file completion list.

Is there a way to exclude certain folders from KDevelop's view of the project?

I'm using KDevelop 4.3.

On Windows, I use the extra buttons of the Logitech Revolution MX to play/pause media playback, and to control volume (level up/down and mute/unmute.)

I cannot seem to find a way to reproduce this behaviour in Ubuntu 11.04.

Specifically I use the thumb wheel to control volume, and the search button to play/pause music.

The thumb wheel seems to have no function, but some applications register it as a click. The search button launches 'search for files'.

Is it possible to re-map these settings?

I'll confess that I'm quite new to Linux in general, so please don't assume anything when answering.

I've been trying to find information online about this audio device. People generally claim that they got it working, but most of the chat about it was from 2007 and they make reference to things like FreeBoB which has now been superceeded by ffado.

They also refer to Jack. I think this is for internal routing of audio, which I don't currently need, afaik.

Mostly I just want to play audio out via this device. All my music creation software is done using Windows/Mac software for now.

I'm worried I'm going to break my system in my naivety, so any tips would be appreciated.

(Note, not enough reputation to tag as firewire)