Simple Tips for developers

Switch to super user account

2012-01-24T16:59:00.002Z

I love this one because its so simple, but so often over looked. In fact it was several years before I discovered it. By default in Ubuntu and most linux installs, the root account is disabled, and most people leave it - which is a good thing. To execute administration commands requires the use of the sudo before the command. This is find if you only have one command, but becomes more cumbersome when you have multiple commands, especially when they're chained together in pipes or other operations. If you'd like to "switch" temporarily into a sudo account, all you need to do is:

$ su -

You will be prompted to enter YOUR password and then you'll be in a super user account. Once you're done simply type:

$ exit

and you'll be back at your own prompt again.

How to add or remove a service under debian linux using the command line

2012-01-19T19:31:00.003Z

update-rc.d automatically updates the System V style init script links /etc/rcrunlevel.d/NNname to scripts /etc/init.d/name. These are run by init when changing runlevels and are generally used to start and stop.

Lets say we want the ssh service to run at boot:

# update-rc.d ssh defaults

OR

$ sudo update-rc.d ssh defaults

And to remove a service just type this:

# update-rc.d SERVICE-NAME remove

OR

$ sudo update-rc.d SERVICE-NAME remove

How do I delete all the thumbs.db files?

2012-01-19T00:33:00.003Z

If while poking around your portable hard drive you notice there seems to be lots of Thumbs.db files, from when your windows based computers last used it, you can get rid of them all, quickly and swiftly with one simple command:

find /media/myharddrive -iname 'thumbs.db' -exec rm -v {} \;

In fact, this little script can be used to remove all files of a particular name - the "iname" means case insensistive by the way.

no such file to load -- openssl

2012-01-18T20:13:00.001Z

Another little trick, using Ubuntu/Mint when trying to execute my command line interface to the Interactive Investor website this morning I was presented with the friendly message:

no such file to load -- openssl

Usually this would simply require a gem install blah but this doesn't work in this particular instance. Instead I was told you simply need to:

sudo apt-get install libssl-dev

Sure no probs, but that didn't solve the problem. I still needed to rebuild ruby with ssl support, and as I'm using rbenv to manage my rubies, I could achieve that with the following command:

ruby-build 1.9.2-p290 ~/.rbenv/versions/1.9.2-p290 --with-openssl-dir=/usr/local

Agent admitted failure to sign using key

2012-01-18T17:57:00.002Z

This morning after migrating from Ubuntu to Mint I wanted to pull all my project code back from github only to be presented with:

Agent admitted failure to sign using the key.
Permission denied (publickey).

I re-generated my keys, and re-added them to github a couple of times but that wasn't the problem. The problem turned out to be ssh didn't know the key was there, even though I was using the standard key location. Probably something to do with the new shell i was using. Anyway the solution was simple, I just needed to tell ssh about the keys and everything worked out:

ssh-add ~/.ssh/id_rsa

How do I find out what shell I'm running?

2012-01-15T18:23:00.002Z

Here is a way to get what your after...using the PID from the shell that your in see who the owner of that process is.

echo $$ # Gives the Parent Process ID
ps -ef | grep $$ | awk '{print $8}' #use the PID to see what the process is.

Creating a persistent bootable USB Stick with Linux Mint, (and the error vesamenu.c32 : not a COM32R image)

2012-01-15T03:01:00.000Z

If you create a bootable stick using Ubuntu's "Startup Disc Creator" you'll probably end up at a black screen with the error vesamenu.c32 : not a COM32R image when using a live cd on a usb stick. DO NOT WORRY!!

Just hit tab and type "live" then enter.

This will carry on the boot as normal.

To fix this little problem automatically just open up your favorite text editor and edit the syslinux.cfg file where it says:

default vesamenu.c32

replace "vesamenu.c32" with "live" and voila!!!! the autoboot we wanted!!

default live
prompt 0
timeout 300

200 Linux Commands for beginners

2011-12-25T03:36:00.000Z

Here is a great list of commands that should help anyone getting started with Linux.

Privileges

sudo command - run command as root
sudo su - open a root shell
sudo su user - open a shell as user
sudo -k - forget sudo passwords
gksudo command - visual sudo dialog (GNOME)
kdesudo command - visual sudo dialog (KDE)
sudo visudo - edit /etc/sudoers
gksudo nautilus - root file manager (GNOME)
kdesudo konqueror - root file manager (KDE)
passwd - change your password

Display

sudo /etc/init.d/gdm restart - restart X (GNOME)
sudo /etc/init.d/kdm restart - restart X (KDE)
(file) /etc/X11/xorg.conf - display configuration
sudo dpkg-reconfigure -phigh xserver-xorg - reset X configuration
Ctrl+Alt+Bksp - restart X display if frozen
Ctrl+Alt+FN - switch to tty N
Ctrl+Alt+F7 - switch back to X display

This command will usually tell you the vendor and model of your graphic card
list
lspci
lspci -v
lspci -v | less

System Services

start service - start job service (Upstart)
stop service - stop job service (Upstart)
status service - check if service is running (Upstart)
/etc/init.d/service start - start service (SysV)
/etc/init.d/service stop - stop service (SysV)
/etc/init.d/service status - check service (SysV)
/etc/init.d/service restart - restart service (SysV)
runlevel - get current runlevel

Package Management

apt-get update - refresh available updates
apt-get upgrade - upgrade all packages
apt-get dist-upgrade - upgrade Ubuntu version
apt-get install pkg - install pkg
apt-get remove pkg - uninstall pkg
apt-get autoremove - remove obsolete packages
apt-get -f install - try to fix broken packages
dpkg –configure -a - try to fix broken packages
dpkg -i pkg.deb - install file pkg.deb
(file) /etc/apt/sources.list - APT repository list

Network

ifconfig - show network information
iwconfig - show wireless information
sudo iwlist scan - scan for wireless networks
sudo /etc/init.d/networking restart - reset network
(file) /etc/network/interfaces - manual configuration
ifup interface - bring interface online
ifdown interface - disable interface

Special Packages (Ubuntu)

ubuntu-desktop - standard Ubuntu environment
kubuntu-desktop - KDE desktop
xubuntu-desktop - XFCE desktop
ubuntu-minimal - core Ubuntu utilities
ubuntu-standard - standard Ubuntu utilities
ubuntu-restricted-extras - non-free, but useful
kubuntu-restricted-extras - KDE of the above
xubuntu-restricted-extras - XFCE of the above
build-essential - packages used to compile programs
linux-image-generic - latest generic kernel image
linux-headers-generic - latest build headers

Firewall

ufw enable - turn on the firewall
ufw disable - turn off the firewall
ufw default allow - allow all connections by default
ufw default deny - drop all connections by default
ufw status - current status and rules
ufw allow port - allow traffic on port
ufw deny port - block port
ufw deny from ip - block ip adress

Application Names

nautilus - file manager (GNOME)
dolphin - file manager (KDE)
konqueror - web browser/filemanager (KDE)
kate - text editor (KDE)
gedit - text editor (GNOME)

System

Recovery - Type the phrase “REISUB” while
holding down Alt and SysRq (PrintScrn) with
about 1 second between each letter. Your system
will reboot.
lsb_release -a - get Ubuntu version
uname -r - get kernel version
uname -a - get all kernel information

Moving around in the file system

pwd "Print working directory" - show what dir you're in.
ls -List the contents of a dir.
ls -l -List the contents of a dir and show additional info of the files.
ls -a -List all files, including hidden files.
cd -Change directory.
cd .. -Go to the parent directory.

Manipulating files and directories

cp -Copy a file.
cp -i -Copy a file and ask before overwriting.
cp -r -Copy a directory with its contents.
mv -Move or rename a file.
mv -i -Move or rename a file and ask before overwriting.
rm -Remove a file.
rm -r -Remove a directory with its contents.
rm -i -Ask before removing a file. Good to use with the -r option.
mkdir -Make a directory.
rmdir -Remove an empty directory.

zipping/taring

tar -cvzf mytar.tar.gz sourcefilesordir - creates a new tar file, verbose options on, runs it through gnuzip,f is the filename
tar -xvf mytar.tar.gz destination - extracts a tar file (this example is compressed with gzip), verbosely, f is the filename
gzip fileordir - compresses a file with gzip.
gunzip file.gz - decompresses a file with gzip.
NB gzip only compresses files, it doesn’t collect them into a single file like a tarball does.

More Commands

Arrow Up: scrolls and edits the command history, press enter to activate.
Shift+pgup: scrolls terminal output up
Shift+pgdown: scrolls terminal output down
CTRL-ALT+DEL reboots the system
Shutdown -h now turns the system off
CTRL C kills the current process
CTRL S Stops the tranfer to the terminal
CTRL Q Resumes the transfer to the terminal
CTRL Z Puts the current process in the background.

hostname - Shows the host name of the system you are on
whoami Displays your login name
date - Displays what your machine thinks the date is
who - Shows who is logged into the machine
rwho-a -Shows all users logged into the server network
finger Shows info on chosen user
last - Show the last users logged into the machine
uptime - Shows the systems uptime
PS - Shows the current user processes
PS -A - Shows all process on the system
uname -A -Displays all info on your host.
free -Shows the free memory in KB
df -h -Shows the disk space details
cat/proc/cpuinfo -Shows the CPU information
cat/proc/filesystems -Shows the file system information in use
cat/etc/printcap -Shows if any printers are hooked up
lsmod -Shows the kernel modules loaded

Malicious Commands You Should (NOT USE) unless you know what you're doing.

This commands will erase your hard drive:
sudo mkfs (This will format your hard drive)
sudo mkfs.ext3 (This will format your hard drive)
sudo mkfs.bfs (This will format your hard drive)
sudo mkfs.cramfs (This will format your hard drive)
sudo mkfs.ext2 (This will format your hard drive)
sudo mkfs.minix (This will format your hard drive)
sudo mkfs.msdos (This will format your hard drive)
sudo mkfs.reiserfs (This will format your hard drive)
sudo mkfs.vfat (This will format your hard drive)

This commands can damage your operating system.

sudo rm -rf / (This will delete all your files on your system)
sudo rm -rf * (This will delete all the files in the current folder)
rm -rf * or rm -rf *.* (This will delete all the files in the current folder)
rm -rf ~/ & (This will destroy your home directory)

Working with Capybara and Rspec?

2011-12-21T02:44:00.002Z

Learn your Rspec Matchers and you'll be flying...

They're all in the yard

How to display the linux version you're using

2011-12-19T15:33:00.001Z

Nice easy one today.

To print out the version of linux you're using try the following in your terminal window:

$ lsb_release -rd
Description:    Ubuntu 11.10
Release:    11.10
 

Get to your server quicker and easier with SSH Aliases

2011-12-13T17:14:00.007Z

When you work on multiple servers and need to access them with different username's you can make your life infinitely easier by setting up some ssh aliases.

This will reduce:

ssh some_user@connect.myserver.com

to:

ssh myserver

To create an alias edit your local ssh config file with a command like:

vi ~/.ssh/config
and add an alias in the form of:

Host aliasname
HostName yourdomain.com
User yourusername
You can have more than one of them. I have one for each of the domains I connect to regularly. Just one little quick tip to type a little less.

trying to use willpower to overcome the apathetic sort of sadness that accompanies depression is like a person with no arms trying to punch themselves until their hands grow back

2011-12-08T23:56:00.001Z

If you've yet to discover the world of hyperbole and a half, please enjoy this link

My problems with the Bundler 1.1 and rubgems.org update

2011-12-08T21:07:00.001Z

Ok so before I start, let me say that I love bundler, it definitely makes my life infinitely better.

This post is about the issue of speed to execute bundle update/install commands.

The issue centres on this "Fetching source index for http://rubygems.org/.”

Its obviously a problem because why would someone want to time it:
https://github.com/bassnode/bundler_timer

Anyway, it seems the bundler team have attempted to resolve it, and its explained very nicely here:
http://patshaughnessy.net/2011/10/14/why-bundler-1-1-will-be-much-faster

My issue is this:

The current version of bundler downloads the whole list each time - what is wrong with doing a sha1 on the file (both client and server) and client checks the sha1 with the server - if there are differences, get the diff patch and apply it. So the first time you run bundler with new gem host it might take a while to get the list, after that it will be lightning fast.

And if you're going to say to me, how can the server provide a diff.patch - for the client to have a file in the first place it must have downloaded it in the past, therefore the "old list" came from the server - so the server simply needs basic git functionality of "diff oldlist newlist".

Something like the following should be sufficient on the server side:

http://rubygems.org/gemlist?<my-list-sha1>

return if my-list-sha1 == latest-list-sha1
return diff get_list(my-list-sha1) get_list(latest-list-sha1)

def get_list(sha1)
#resolve sha1 to a file however you see fit
end

This approach would make it very simple implement support on any custom gem servers - heck the code could even be hacked up in a gist.

So what are the problems with this solution?

The only one I can think it portability of "diff" and "sha1" though I'm sure that's been solved as well.

Anyway I would be very keen to hear thoughts and opinions about this. I realise its already too late to influence the internal design of bundler but it would be great to understand why this concept has been rejected (I'm assuming they already thought of something like this)

Update the timezone on your Ubuntu server

2011-12-06T23:22:00.001Z

$ dpkg-reconfigure tzdata

Will allow you to update the timezone to make sure your server is set to the right zone.

Flickr

2007-05-08T12:48:00.001+01:00

This is a test post from , a fancy photo sharing thing.

Wow factor for Firefox

2007-01-12T10:34:00.000Z

Absolutely no use, but it looks great!!

Try this plugin for firefox!!

Web 2.0's not all about being "Web 2.0" after all!!!

2006-06-01T12:22:00.000+01:00

So, after all the rantings and ravings about "Web 2.0" being all about opening up data, sharing.......

Clearly, O'Reilly have reached the inevitable backlash, victims of their own success!!

Hamachi - stay connected...

2006-04-25T16:49:00.000+01:00

Think - LAN over the Internet, Zero-configuration VPN, Secure peer-to-peer.

Access computers remotely. Use Windows File Sharing. Play LAN games. Run private Web or FTP servers. Communicate directly. Stay connected.

This is truely awsome work!!

Hamachi is a zero-configuration virtual private networking application with an open security architecture and NAT-to-NAT traversal capabilities.

Hamachi is the first application to mix seemingly unrelated networking technologies in one powerful package to deliver an unprecedented level of peer-to-peer connectivity.

www.hamachi.cc

Google Calendar Button for the Google Toolbar

2006-04-18T12:43:00.000+01:00

I couldnt find an official Google Calendar Button for the Google Toolbar, so i made one.
Click here to install it.

Currently it does not support getting an atom feed of the latest events (like the GMail button does) but its only because i dont have the correct urls. If someone knows, or knows some who does, please let me know...

Google Calendar

2006-04-18T09:51:00.000+01:00

For those who havent seen it, go give Google Calendar a try, as expected its got loads of nice features...

Find out what your subconscious mind really thinks about open source products?

2006-04-13T10:22:00.000+01:00

Careful though, it might not be what you were expecting!!

This web site presents a method that demonstrates the conscious-unconscious divergences much more convincingly than has been possible with previous methods. This new method is called the Implicit Association Test, or IAT for short.

https://implicit.harvard.edu/implicit/demo/featuredtask.html

YAGS - Yet Another goggle Service

2006-02-07T10:07:00.000Z

Google Talk inside Google Mail....

If you don't have already have a small account, now really is the time to get one. GTalk chats are now saved in your Gmail account automatically, with a nice "off the record" button for those times you really dont want people to know....

Anyone who's played with Google's Orkut system would know the ingenious social networking that's inside there, but the overall look and feel is not standard Google style. What I'd really love to see is (and what I've emailed asking for) is those same features (rating/categorizing relationships etc) INSIDE your gmail contacts, and a nice notes/sticky notes feature as i'm constantly using the draft's for that at the moment.

Google Sitemaps

Again, another ingenious system to help you work with google to get your site indexed better, and tune the performance of it.

...

The personalized homepage, and saved search histories are also incredibly useful....

Who knows where it will all end, but I've happily migrated myself and my belongings from Microsoft/hotmail, except for messenger, and there's two reasons for that, one is I still enjoy using emoticons in chat, and google talk, while being a very smart app doesn't currently support them (and probably wont, just not google style IMHO). The other more important reason is that all my contacts are still msn monkeys, and most aren't willing to switch, so until I can chat to them from my google talk account, it remains relatively unused. Now I know gtalk is built on Jabber, and Jabber is designed to be the inter-operable messaging platform, but until google add the transports to their Jabber servers I'm stuck using two clients....

One day, I'm sure...

I dont know how "pc" this is, but its too funny not too share

2005-09-21T17:43:00.000+01:00

Go to Rachel Steven's website and click on the "Game" link.

After a few moments the music will start playing, and just listen to the words in the first verse, "Oooooh, i let you..........." from this beautiful, sweet little angel......or perhaps not!!!!

I cant believe she didnt realise what she was singing......or perhaps she did!!!

rachelstevensofficial

MySql Query Browser

2005-08-30T00:29:00.000+01:00

MySQL have clearly stepped up a gear in their offerings over the past couple of years, and most recently has seen the release of a couple of extremely powerful desktop control tools for their awsome database server. If you use mySQL at all and havent checked out these tools yet, i strongly recommend it. Most notably in the query browser tool is a facility hidden away in the tools menu. Its called RegEx Text Importer, and while the words regex might a shiver down the spine of a few, once tamed, this beast offers you a fantastic opportunity to fill your database up with all sorts of useful data to enhanced your website.

Find your local sex offender!!!

2005-08-28T19:17:00.000+01:00

While working on my own google map site, i stumbled across this map.
Only in america eh!!