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Command Line HowTo Linux Ubuntu

ERROR: Failed to build gem native extension.

While attempting to install a package from gem, I encountered this issue:

sudo gem install dashing
Building native extensions.  This could take a while...
ERROR:  Error installing dashing:
	ERROR: Failed to build gem native extension.

        /usr/bin/ruby1.9.1 extconf.rb
/usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load such file -- mkmf (LoadError)
	from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
	from extconf.rb:2:in `
' Gem files will remain installed in /var/lib/gems/1.9.1/gems/eventmachine-1.2.3 for inspection. Results logged to /var/lib/gems/1.9.1/gems/eventmachine-1.2.3/ext/gem_make.out

Simply to solve this you just need to install ruby-dev packages on ubuntu:

sudo apt-get install ruby-dev
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Linux Ubuntu Uncategorized

Linux Mint: “Could not download all repository indexes”

When running

sudo apt-get update

or attempting to update via the Update Manager in Linux Mint (13), I was fronted with the following error:

Failed to fetch http://packages.linuxmint.com/dists/deb ... tion-en_US Unable to connect to packages.linuxmint.com:http:
Failed to fetch http://packages.linuxmint.com/dists/deb ... slation-en Unable to connect to packages.linuxmint.com:http:
Failed to fetch http://packages.linuxmint.com/dists/deb ... tion-en_US Unable to connect to packages.linuxmint.com:http:
Failed to fetch http://packages.linuxmint.com/dists/deb ... slation-en Unable to connect to packages.linuxmint.com:http:
Failed to fetch http://packages.linuxmint.com/dists/deb ... tion-en_US Unable to connect to packages.linuxmint.com:http:
Failed to fetch http://packages.linuxmint.com/dists/deb ... slation-en Unable to connect to packages.linuxmint.com:http:
Some index files failed to download. They have been ignored, or old ones used instead.

This is caused by missing repositories which are either old, broken or currently down. In order to fix it, simply run:

sudo apt-get update fix-missing

If this option doesn’t work, try changing the repository mirrors with the following guide.

Categories
HowTo Linux Raspberry Pi Ubuntu

Unknown encoder ‘libx264’

If you encounter a problem similar to the following, where you’re missing the libx264 codec try this solution.

avconv -r 10 -i image%06d.jpg -r 10 -vcodec libx264 -crf 20 -g 15 timelapse1.mp4

avconv version 0.8.6-6:0.8.6-0ubuntu0.12.10.1, Copyright (c) 2000-2013 the Libav developers
built on Apr 2 2013 17:02:16 with gcc 4.7.2
Input #0, image2, from 'image%06d.jpg':
Duration: 00:02:21.20, start: 0.000000, bitrate: N/A
Stream #0.0: Video: mjpeg, yuvj420p, 2592x1944, 10 fps, 10 tbr, 10 tbn, 10 tbc
Unknown encoder 'libx264'

In order to acquire libx264, on Debian based distros (Ubuntu, Mint, Raspbian) install the following package:

 sudo apt-get install libavcodec-extra-53
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Command Line Fedora Linux Posts Ubuntu

Linux USB Errors with usb-creator-gtk “stdin: I/O error stdin: error 0 /init: line 1: can’t open /dev/sr0: No medium found”

After installing Ubuntu on a USB stick with the Ubuntu USB Startup Disk Creator (usb-creator-gtk) you might encounter an error such as the following:

stdin: I/O error
stdin: error 0
/init: line 1: can't open /dev/sr0: No medium found

This is actually a bug with the software and isn’t anything you’ve done wrong. It seems to be a bug that’s effecting users running Karmic, Lucid, Maverick and Natty so it’s a pretty wide spread issue.

The best way I have found to get around this issue is to install and run unetbootin to create live USBs. If you’re using linux it should be found in the usual place you can install things.

Installation:

Ubuntu/LinuxMint/Debian:

sudo apt-get install unetbootin

Fedora/OpenSuse:

sudo yum install unetbootin
Create a live USB:

To install a distro it’s pretty simple, either select it from the “Distribution” option and pick a distribution and version, UNetbootin will then actually download it and install it for you. Alternatively you can pick an Diskimage and browse for the ISO file you download (and would usually burn to a CD/DVD) and install from that. Select the USB Drive at the bottom and hit ok and it’ll install a bootloader, the system and you’ll be up and running in no time.

Persistence File:

If you wanted a persistence install which allows you to save files, settings and installed programs you’ll have to do a little manual work as it currently doesn’t support that option.

Go to http://unetbootin.sourceforge.net/diskimg/ and download one of the files (128mb.zip, 256mb.zip, or 512mb.zip) corresponding to the amount of persistent space you want (make sure the size of the persistent disk image is smaller than the free space you have on your USB drive).

You’ll then need to edit the syslinux.cfg file that was created by UNetbootin in the root of the directory (just open it with a text editor) you should see something similar to the following:

label unetbootindefault
menu label Default
kernel /ubnkern
append initrd=/ubninit file=/cdrom/preseed/ubuntu.seed boot=casper quiet splash —

So on the line that starts “appen initrd=” you’ll want to add the option of “persistent”, it should then look like the following:

NOTE: WordPress changes my double dash at the end of the last line to a single long dash, this won’t work. It’s easiest just to add the final word before the double dash in the file, do not copy and paste this in to your file. If you do, you will get more errors.

label unetbootindefault
menu label Default
kernel /ubnkern
append initrd=/ubninit file=/cdrom/preseed/ubuntu.seed boot=casper quiet splash persistent —

I added this line to all that used the “file=/cdrom/preseed/ubuntu.seed” option, since that’s the image that’s being opened and it should then change all options on the bootloader that will load the ubuntu install.

Categories
Arch Linux Fedora HowTo Linux Posts Ubuntu

Linux Media Players And Flash Not Stopping The Screensaver

It’s a pretty common problem, one which could be solved by pretty much the following sentence: ‘[Insert Linux Distro], [Insert Media Player] not stopping screen saver when playing videos.’ And, yeah, it’s very annoying. Something that should have been fixed thousands of releases ago, just like most common Linux problems. Luckily though there is a fix, it’s easy and it’s awesome.

Introducing: Caffeine, “An application to temporarily prevent the activation of both the screen saver and the “sleep” powersaving mode.” – https://launchpad.net/caffeine

Essentially what this program does is look for processes running on your machine (you can do this too, just run ‘ps -A’ in a terminal emulator to see a list of everything), so you set process names which the program should look out for, for example ‘vlc’ and when there is a process with this name Caffeine disables the screensaver, when the process stops the screensaver is re-enabled. It even comes with a little tray icon which allows you to manual enable or disable the screensaver/power management with a single click.

Installation (Ubuntu):
sudo add-apt-repository ppa:caffeine-developers/ppa
sudo apt-get update
sudo apt-get install caffeine
Usage:

You’ll be able to see if caffeine is running by the tray icon the first time you use it (this can be disabled in the settings).

Caffeine Running (Screensaver / Power Management Enabled)
Caffeine Running (Right Click Settings)
Caffeine Running (Screensaver / Power Management Disabled)
Adding Processes:

To add a process which will disable the screensaver from being activated, for example VLC so we can watch a movie without constantly having to wiggle the mouse:

First, run VLC (or whatever other media player you wish and just replace VLC for that for the other few steps)

Next, right click on the Caffeine tray icon and select “Preference”.

Click the “Add” button.

List of processes already disabling the screensaver, note Totem is added here.

You should be greeted by a list of the running processes, select the name of the media player (this case, vlc) if it isn’t there check under the “Recent Processes” tab or alternatively just write the command you would use to run this program from the command line.

Adding VLC to processes to disable the screensaver.

Finally click the “Add” button and close the preferences window, that pesky screensaver should no longer be bothering you!

Stopping Flash from enabling the screensaver:

Okay, this is actually really easy, if you’re using Chromium or Google Chrome or Firefox, you’ll just want to add the processes ‘npviewer.bin’ to list, you can use the above instructions to do so.

Categories
HowTo Linux Posts Ubuntu

How To: Fix “Unknown keyword in configuration file.” Ubuntu USB Boot

Attempting Boot From USB Device

SYSLINUX 3.63 Debian-2008-07-15 EBIOS Copyright (C) 1994-2008 H. Peter Anvin
Unknown keyword in configuration file.
boot:
_

After creating a USB bootable version of Ubuntu from the Startup Disk Creator (or usb-creator-gtk) and attempting to boot, I was greeted by the error above. It might look a bit scary but it’s really easy to fix, just plug the USB flash drive into a computer (windows or linux, mac too probably but I haven’t tried that.)

Solution 1:
  1. Open the the syslinux folder in the root of the flash drive.
  2. Inside is a file called syslinux.cfg you’ll want to edit that.
  3. Find the line “ui gfxboot bootlogo” and simply remove the “ui “.
  4. Save and try booting again.

Below is how my syslinux.cfg file looks after editing:

# D-I config version 2.0
include menu.cfg
default vesamenu.c32
prompt 0
timeout 50
gfxboot bootlogo


Solution 2

Alternatively it looks as though there is another way of fixing this issue if there is no “ui” in the file, this is to do as followed (as pointed out in the comments below):

  1. Type “help” and press enter
  2. Hit Enter again

This should boot correctly and shouldn’t need to be done every time.