A collection of useful commands I've picked up over time (history | grep X). Understanding the purpose of each parameter is left to the reader - note typing '/' in man lets you search for specific terms in the manual page. Note that these commands have all been tested on an Ubuntu installation, and with the exception of package management they should work universally. Many commands require extra permissions and start with "sudo" - take extra caution when using these. I update this page pretty frequently. Always lots to learn! :)

Index of commands:

Other stuff:

On getting nvidia_experimental_310 to work:

I had issues getting the nvidia_experimental_310 package working. It turned out there was a "nvidia_experimental_310" entry in a file "/etc/modprobe.d/blacklist-local.conf" causing the trouble. How and why that got there I may never know. Commands I tried to track down this problem and my path to a solution:

Show loaded modules (with 'nvidia' in name):

lsmod | grep nvidia Not loaded. Show errors in X.org log: cat /var/log/Xorg.0.log | grep '(EE)' Error found, suggests checking kernel log:

[ 10.865] (EE) NVIDIA: Failed to load the NVIDIA kernel module. Please check your
[ 10.865] (EE) NVIDIA: system's kernel log for additional error messages.
[ 10.865] (EE) Failed to load module "nvidia" (module-specific error, 0)

Show kernel log (and view in 'less'):

cat /var/log/kern.log | less Last entry shows it trying to load nvidia module? Not very helpful unfortunately.

Show all nvidia kernel objects:

locate *.ko | grep nvidia ...

Existence of the kernel object for the current version of the kernel I'm running (uname -r) is encouraging as it means when installing the nvidia_experimental_310 package it compiled OK. Let's try to link it into the kernel again ourselves.

Load a module (in this case, 'nvidia_experimental_310'):

sudo modprobe nvidia_experimental_310 modprobe: WARNING: Not loading blacklisted module nvidia_experimental_310

Blacklisted? Huh?

Search all blacklisted modules (whose name contains 'nvidia'):

cat /etc/modprobe.d/blacklist* | grep nvidia blacklist nvidiafb
blacklist nvidia_experimental_310

Aha! After removing blacklist-local.conf which contained the above entry, I tried again.

Load a module, then restart display manager:

sudo modprobe nvidia_experimental_310 sudo service restart lightdm

Working well!

copy/pasting into the terminal:

"Control-Shift-V" pastes text directly into the terminal, avoiding the need to right click and choose "Paste" each time.

filesystem mounting options for a solid state drive:

You can edit "fstab" (the file system table) by doing the following:

gksudo gedit /etc/fstab To identify which is the SSD: blkid Listing all partition information can be helpful to identify the drive: sudo fdisk -l Under "options" in the fstab, for the SSD, adding discard adds TRIM support, adding noatime, nodiratime disables extra writes to keep track of when files and directories were last accessed. For instance if the SSD line in fstab is: UUID=03f7d0a1-2fcb-4878-afef-8487799df4a4 / ext4 errors=remount-ro 0 1 Change it to the following, using commas to separate each option: UUID=03f7d0a1-2fcb-4878-afef-8487799df4a4 / ext4 discard,noatime,nodiratime,errors=remount-ro 0 1 Do not forget to save and restart.

using udisks and gnome-session-properties to automount partitions on login:

The easiest way to set up automatic mounting is using the gnome-disks tool, and choosing "Edit mount options...". The next easiest way is by running gnome-session-properties and add the following command: /usr/bin/udisks --mount /dev/sdb1 where "/dev/sdb1" the partition you wish to mount. Using a UUID is preferred in case drives get switched around, to view partition UUIDs use: blkid Given the UUID of the partition, change the udisks command parameters to: /usr/bin/udisks --mount /dev/disk/by-uuid/1234567890ABCD Or, one can edit the filesystem table file (/etc/fstab).

changing file ownership on a USB drive not formatted to FAT32:

The drive will not allow you to write to it since you are not the owner of files on that filesystem (the root account is). Chances are, while FAT* does not support the concept of user ownership, the existing filesystem does (e.g. ext4), causing the problem. Use the "chown" command to change the ownership to your account. With the drive mounted, do: sudo chown james /media/james/kingston32gb This changes the files mounted to /media/james/kingston32gb to be owned by user james. You will then be able to both read and write files to the device.

getting multi-monitor settings with nvidia-settings to stick after reboot:

I had an issue with three display devices having their positions reset every reboot (two standard monitors, plus an Oculus Rift). The Oculus Rift would always be reset to be positioned between the two monitors. Using nvidia-settings and saving to /etc/X11/xorg.conf never seemed to work. Bring up a terminal and run: gksudo nvidia-settings Set the desired display configuration. Then, save xorg.conf configuration settings to: /usr/share/X11/xorg.conf.d/xorg.conf You may notice when browsing the directory /usr/share/X11/xorg.conf.d/ that a file xorg.conf.backup was instead saved. You can copy or rename this file using gksudo nautilus using a GUI, or use the terminal command cd /usr/share/X11/xorg.conf.d/ sudo cp xorg.conf.backup xorg.conf On restart, the monitor settings should be remembered! (Tested on Ubuntu 13.04.)

removing overlay-scrollbar from default Ubuntu installation:

The selection zone to bring up the overlay scrollbar I have issues with. It appears when the cursor is over the left side of the window edge, but is displayed on the right. When moving the cursor to the right to manipulate the control, it often disappears - I find this frustrating.

Fortunately, it is easy to disable the "overlay scrollbars". On Ubuntu 12.04:

gsettings set org.gnome.desktop.interface ubuntu-overlay-scrollbars false and to bring them back: gsettings reset org.gnome.desktop.interface ubuntu-overlay-scrollbars For Ubuntu 12.10 and 13.04, to disable them: gsettings set com.canonical.desktop.interface scrollbar-mode normal and to bring them back: gsettings reset com.canonical.desktop.interface scrollbar-mode The command should take effect immediately. Previously, I removed the package using "sudo apt-get remove overlay-scrollbar". While that worked, warnings would appear about the missing "overlay-scrollbar" GTK module when running applications.

fixing the fontconfig warning when running applications:

When running my Qt applications, under application output I would always see the message: Fontconfig warning: "/etc/fonts/conf.d/50-user.conf", line 9: reading configurations from ~/.fonts.conf is deprecated. This can be fixed by doing the following: mkdir ~/.config/fontconfig mv ~/.fonts.conf ~/.config/fontconfig/fonts.conf The change should take effect immediately -- applications will no longer complain about it. (Tested on Ubuntu 13.04.)

setting up an environment for making documents with TeXworks and LaTeX:

On a new Ubuntu installation, to produce academic papers I install TeXworks software, the latexmk script, and some LaTeX packages, using the following: sudo apt-get install texworks latexmk texlive-latex-recommended texlive-latex-extra In TeXworks, Edit>Preferences>Typesetting. Add latexmk processing tool with the program usr/bin/latexmk and the following command line arguments: -e $pdflatex=q/pdflatex $synctexoption %O %S/ -pdf $fullname Check "view PDF after running", press OK. For default - set to latexmk.

switching between qt4 and qt5 with qtchooser:

I reinstalled Ubuntu 13.04 on a machine (comes with qt4) overtop a 13.10 installation (comes with qt5). I found when building through qtcreator that there were errors in relation to using the qt5 libraries rather than qt4. The program "qmake" is a symlink to the program "qtchooser", which was configured to use qt5. To set it back to qt4, the /usr/share/default.conf symlink needs to point to qt4.conf: cd /usr/share/qtchooser sudo rm default.conf sudo ln -s qt4.conf default.conf

open a terminal through nautilus:

Use the following command to install the extension: sudo apt-get install nautilus-open-terminal

youtube issues with chromium:

On an Ubuntu 12.04 installation with chromium, youtube videos often fail to load with the message "This video is currently unavailable". The fix (in my case): sudo apt-get remove chromium-codecs-ffmpeg sudo apt-get install chromium-codecs-ffmpeg-extra

hostnames, avahi and .local:

You may find you are unable to connect using the hostname to another computer on the network (e.g. for a computer whose hostname is "whirringbox"): ping whirringbox ping: unknown host whirringbox Ubuntu (and others) include software called avahi, "zero-configuration networking software" which includes support for something called mDNS (or the "multicast Domain Name System"). On Ubuntu installations, there will be a program called avahi-daemon running. For example, if we run on whirringbox: ps -ax | grep avahi this displays 684 ? S 0:00 avahi-daemon: running [whirringbox.local] 687 ? S 0:00 avahi-daemon: chroot helper 8350 pts/0 S+ 0:00 grep --color=auto avahi The purpose of the avahi-daemon process is to make the computer accessible on the local network. Supporting mDNS, avahi-daemon waits for a message on the local network requesting the host with name "whirringbox.local" to identify itself. Then, the avahi-daemon replies to this message, providing the IP address of whirringbox. So in general, to connect to an Ubuntu machine by hostname for an mDNS-supporting system, you need to add ".local": ping whirringbox.local PING whirringbox.local ( 56(84) bytes of data. 64 bytes from whirringbox.local ( icmp_req=1 ttl=64 time=0.543 ms 64 bytes from whirringbox.local ( icmp_req=2 ttl=64 time=0.150 ms 64 bytes from whirringbox.local ( icmp_req=3 ttl=64 time=0.152 ms I find this a great alternative to the idea of setting up static IP addresses and messing with /etc/hosts.

linker errors using webkitwidgets:

When attempting to add a webpage viewer to my Linux Qt5 application (Ubuntu 14.04) via a "QWebView", part of the "webkitwidgets" module (QT += webkitwidgets), I was missing some development libraries which were causing numerous linker errors (libraries which could not be found). Many related to gstreamer, but there were a few others. Installing the following few packages fixed this for me: sudo apt-get install libgstreamer0.10-dev sudo apt-get install libxslt-dev sudo apt-get install libgstreamer-plugins-base0.10-dev

convert a PDF into a series of images:

Use the command line utility pdftoppm: pdftoppm -png slides.pdf slide_imgs/slide where -png defines the format (e.g. png, jpg) can be specified, slides.pdf is the input file, and slide_imgs/slide is the prefix for each filename (this puts slides into a slide_imgs subdirectory).

remove cached startup errors:

You may encounter some startup errors with a dialog saying "system program problem detected", even if nothing is actually wrong. These may be caused by errors that occurred long ago that have been not been cleared properly. To do this manually, use the following: sudo rm /var/crash/* If you still have startup error dialogs after doing this, check the contents of the /var/crash directory.

digitally sign a PDF:

Xournal is a great bit of software that allows you to import a PDF file (with formatting intact - the same cannot be said for LibreOffice), and place text and images into the document and export. sudo apt-get install xournal

s3cmd - Manage Amazon S3 buckets (webhosting):

s3cmd is a great little command line application which lets you manage Amazon S3 buckets. sudo apt-get install s3cmd An often used command (put it in a script if used frequently), to recursively copy/update/delete files from a local working directory to the remote: s3cmd sync * s3://www.example.com --acl-public --progress --verbose --delete-removed