Linux Cheat Sheet

I wanted a cheat sheet which would display pretty nicely on my Kindle 3, I found a bunch of great ones but none were formatted well to fit on the Kindle so I went ahead and compiled my own from the most useful stuff I found on the others. I’ve put in commands for manipulating text files, searching, permissions, system info and a bunch of other stuff too so check it out if you’re in need of a reference page. I’ll update it on here as it gets updated too.

Download Here

Sources:

How To: Install Pyrobot in Ubuntu

A quick guide for getting pyrobot running in Ubuntu, I’ve managed to get it running on 32bit and 64bit Ubuntu (10.10) so follow the guide accordingly to whichever architecture you’re using (64bit is about half way down the post).

32-bit

1. Download this file, or copy the below into a file and save it as pyroinstall.sh to your home dir.

#!/bin/sh

currentdir=$(pwd)

sudo apt-get install build-essential python2.6 python2.6-dev python-tk python-numeric libjpeg62-dev libncurses5-dev swig

wget http://pyrorobotics.org/download/pyrobot-latest.tgz

tar -zxvf pyrobot-latest.tgz

cd pyrobot

python configure.py

make

sed -ie 's/-e #!/#!/g' $currentdir/pyrobot/bin/pyrobot
sed -ie 's/-e # /# /g' $currentdir/pyrobot/system/version.py

echo 'export PATH=${PATH}:'$currentdir'/pyrobot/bin' >> $currentdir/.bashrc

Note: The ‘ in the code highlighter I have above won’t work in terminal, there isn’t much I can do about it so you’ll have to re-write it. Also if you’re doing this manually change the “$currentdir” to “~” if you are doing it in your home directory.

2. Make sure this file is in your home directory (e.g /home/alex/pyroinstall.sh) and make it executable:

 chmod +x pyroinstall.sh

3. Run the usual way (as super user because it has to install stuff etc):

 sudo ./pyroinstall.sh

4. It’ll ask you some questions, below are the answers I used – you can use other configurations if you know what you need. I also put the full output in pastebin ’cause it was bunging up the guide - http://pastebin.com/Kc5jyhja

1. 	2.6
2. 	/usr/include/python2.6
3. 	/usr/bin/python2.6
4. 	/etc/X11
5. 	none
6.01	n
6.02	n
6.03	n
6.04	n
6.05	n
6.06	n
6.07	n
6.08	n
6.09	n
6.10	n
6.11	y
6.12	y

5. Once it’s done reboot or run:

 source ~/.bashrc

6. Allow read/write/execute permissions for the pyrobot folder:

 sudo chmod -R 777 ~/pyrobot

You should all be done, try typing the following to get it running!

 pyrobot

64-bit

In order to get pyrobot running on 64bit, you basically need to add -fPIC to CFLAGS in all the relative Makefiles as explained in this mailing list post – http://www.mail-archive.com/pyro-users@pyrorobotics.org/msg00344.html - Lucky for you I’ve already gone through the effort of doing it and compressed it (download here you won’t need to if you are going to run the script though, it’ll do it for you..).

This script should download the file, configure and make and output the path to the .bashrc file for you (similar to the 32bit one does) so download this file, or copy and paste the script below into a file in your home directory:

#!/bin/sh

currentdir=$(pwd)

sudo apt-get install build-essential python2.6 python2.6-dev python-tk python-numeric libjpeg62-dev libncurses5-dev swig

wget http://dl.dropbox.com/u/307455/pyrobot-5.0.0_64bit.tar

tar -zxvf pyrobot-5.0.0_64bit.tar

cd pyrobot

python configure.py

make

echo 'export PATH=${PATH}:'$currentdir'/pyrobot/bin' >> $currentdir/.bashrc

2. Make sure this file is in your home directory (e.g /home/alex/pyroinstall64.sh) and make it executable:

 chmod +x pyroinstall64.sh

3. Run the usual way (as super user because it has to install stuff etc):

 sudo ./pyroinstall64.sh

Steps 4. 5. and 6. are the same as above..

Change Default Editor

If you want to change the default editor from emacs to anything else (this will change the default editor used in other terminal applications too..) use the following commands, just change gedit to whatever you’d like (vi, vim, kedit etc):

echo "export EDITOR=/usr/bin/gedit" >> ~/.bashrc
source ~/.bashrc

Any problems leave a comment and I’ll try and help as best as I can..

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.

Ubuntu Disconnecting from Wi-Fi and Failing to Reconnect.

I have an updated fix for this issue using a startup script to connect and a time scheduled script for checking the connection, rather than having one constantly running in the background, avalible here – http://alexsleat.co.uk/2011/01/09/a-more-elegant-solution-to-ubuntu-wi-fi-reconnecting-issue/

I’ve been having some trouble with my wifi on Ubuntu recently but I think it’s because I’m almost out of range of the access point. The problem is that once it disconnects it never seems to be able to reconnect unless wireless is disabled and re-enabled. No doubt there is another way of fixing this issue but it gives me a chance to write my first shell script.

In short the script disables network-manager (it was trying to do things auto which was screwing with things), sets up the connection and connects then checks for a string in the wireless card parameters which will only occur if it’s disconnected, if the string appears it’ll disable and re-enable the wireless device which seems to allow it to connect again. If it’s connected it’ll wait 3 minutes (180 seconds) before checking again where as if it does disconnect it’ll check again 30 seconds after it’s tired rebooting the device.

Here’s the script, be sure to try it if you’re having the same problem (you might need to change the wireless device ‘wlan1′ to yours) and comment if I’m doing something wrong or there’s another way around this, cheers.

#!/bin/bash

service network-manager stop

iwconfig wlan1 essid NETWORKNAME
iwconfig wlan1 key NETWORKKEY
ifconfig wlan1 up
dhclient3 wlan1

while true;
do

if (iwconfig wlan1) | grep -o "Access Point: Not-Associated"
then
	ifconfig wlan1 down
	echo "not connected, rebooting Wifi"
	ifconfig wlan1 up
	sleep 30
else
	echo "connected"
	sleep 180
fi

done

gedit – failed to load type module: menu_proxy_module_load | Ubuntu

(gedit:2205): Gtk-WARNING **: Failed to load type module: (null)

`menu_proxy_module_load’: gedit: undefined symbol: menu_proxy_module_load

Annoying error, seems to has no serious effect on it running but just nice to clean stuff up so just install ‘appmenu-gtk’.
sudo apt-get install appmenu-gtk

The list of sources could not be read – Ubuntu

E: Type ‘n’ is not known on line 2 in source list /etc/apt/sources.list.d/bean123ch-burg-lucid.list

E: The list of sources could not be read.

To fix this or similar errors open the file, for example “/etc/apt/sources.list.d/bean123ch-burg-lucid.list” and check for rouge characters. In this case there was new line with the letter ‘n’ in place, removing it solved the issue. Make sure to run “sudo apt-get update” to refresh the sources and everything should be fixed. I was also unable to see any software in the “Ubuntu Software Center” because of this.

September

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HowTo: Install & Use Resynthesizer for GIMP

Remember this Photoshop CS5 sneak peak showing off it’s latest and greatest feature Content-Aware Fill a couple months ago, well it turns out a reasonably old plug-in for GIMP (GNU Image Manipulation Program) named Resynthesizer seems to work just as great and because it is what it is, it’s free and open-source.

Installing on Ubuntu 9.10/10.04 install:

sudo apt-get install gimp-resynthesizer

or for the Source/Windows/Fedora Core 4 versions see the download section.

Once you have it installed, it’s simple to use really just select something on your image that shouldn’t be there and right click on the selection Filters -> Map -> Resynthesize.. and up should pop an options box, these settings are pretty standard and will get rid of most things given that they aren’t too big. It’s best if you’re not getting the results you want to play around with the settings yourself to get to know them better.

Click after the break for an example with step by step guide. Continue reading HowTo: Install & Use Resynthesizer for GIMP

Remember this Photoshop CS5 sneak peak showing off it’s latest and greatest feature Content-Aware Fill a couple months ago, well it turns out a reasonably old plug-in for GIMP (GNU Image Manipulation Program) named Resynthesizer seems to work just as great and because it is what it is, it’s free and open-source.

Installing on Ubuntu 9.10/10.04 install:

sudo apt-get install gimp-resynthesizer

or for the Source/Windows/Fedora Core 4 versions see the download section.

Once you have it installed, it’s simple to use really just select something on your image that shouldn’t be there and right click on the selection Filters -> Map -> Resynthesize.. and up should pop an options box, these settings are pretty standard and will get rid of most things given that they aren’t too big. It’s best if you’re not getting the results you want to play around with the settings yourself to get to know them better.

Click after the break for an example with step by step guide. (more…)

HowTo: Find Recently Used Commands in Linux

One of my most used commands in Linux is the history command, it lists all your recent commands. The problem with this is you might have to scroll through hundreds before you get to one of any interest, so adding grep to search through these and bring back only relative one’s is great.

Give it a try (just change searchcriteria for what you want like apt-get or tar):

history | grep searchcriteria

Manual pages:

HowTo: Fix Can’t Click on Flash in Ubuntu (64bit)

There is a pretty quick fix for not being able to click flash on websites such as YouTube, just simply add the line below into the following file and restart your web browser and all should be fine:

sudo gedit /usr/lib/nspluginwrapper/i386/linux/npviewer

Add in the line (above the last line):

export GDK_NATIVE_WINDOWS=1