The script requires only one variable in the configuration which is your username. You are prompted for your password each time you run the script to tweet. If you have a url you would like to share, the script will connect to the is.gd API to shorten the URL. The script will then subtract the length of the shortened url from the 140 total, as well as the space required to retweet (RT @username) the message for a total length available for the tweet. If you go beyond this length, you will be notified how far over you’ve gone. The script then sends the tweet via cURL with your message followed by the shortened URL at the end.

Information

• @name	Post to Twitter
  @filename	post_to_twitter.sh
  @description	This script will post to your twitter account from a Linux shell. You will need to enter your username in the configuration section. You will be prompted for your password each time you run the script.
  @author	Mark Stoecker
  @version	0.1

Installation:

• Click here to download this script
• You can also download this through your Linux shell with the command: wget http://www.poundbangwhack.com/scripts_source/shell/post_to_twitter.sh.txt
• Once downloaded, upload the file to the home directory of your server/computer and save it with a .sh extension: mv ~/post_to_twitter.sh.txt ~/post_to_twitter.sh
• Add execute permissions to the script with chmod a+x ~/post_to_twitter.sh
• Run the script with the command ~/post_to_twitter.sh

Configuration:

• Open the script in any text editor and edit the line u="" by adding your Twitter username between the quotes.

Bugs:

• No known bugs at this time

To Do:

• Nothing to do at this time

As always, if you have comments or suggestions, please share them below and they may be included in future versions of the script.

What’s the difference between installing software using RPM vs. YUM?

As long as the software works, it doesn’t matter right? Well, for those of you obsessive-compulsive types, I feel your pain. Not only do I want it to work, but I want to know why. So I decided to take it upon myself to answer this question and share my findings.

Both RPM, “RPM Package Manager” (formerly “Red Hat Package Manager”), and YUM, “Yellow dog Updater, modified”, are Linux package management systems. Package management systems are often confused with installers. The following table details the main differences between a package management system and an installer:

Above table provided by Wikipedia

Based on the above table, you can see that a package management system is it’s own piece of software that is often bundled with the OS, whereas an installer is bundled with each individual piece of software.

RPM is a pretty straightforward utility. Per the RPM man page,

RPM is a powerful Package Manager, which can be used to build, install, query, verify, update, and erase individual software packages.

In additiona, rpm can also be used to verify the digital signature of the packages you are installing to verify it has not been changed. RPM was originally developed for Red Hat Linux, but now is shipped with many Linux distributions including Fedora, Mandriva, RHEL, SUSE, CentOS, Yellow Dog, and more (not Ubuntu, sorry).

YUM is honestly not much different from RPM. From the YUM man page,

YUM is an interactive, automated update program which can be used for maintaining systems using RPM.

So YUM actually is, in essence, an advanced version of RPM. According to Wikipedia, YUM is a “package-management utility for RPM-compatible Linux operating systems”. So really, you can only use YUM if you are on one of the above RPM enabled systems. To me that means that YUM was created to improve RPM.

Both utilities are going to perform the exact same functions. However, one big advantage that YUM has over RPM, is that YUM will automatically resolve package dependencies. If the package being installed requires additional dependencies, YUM can install those automatically, while RPM will simply prompt to install those first. This can save some time if the rpm you are installing requires multiple dependencies, say for instance if you are installing Gnome or KDE. Another benefit to YUM Is that it can be modified with Python plugins. For instance, the yum-downloadonly plugin can be installed so yum will download the rpm package, but will not install it.

After researching the issue, I have come to the conclusion that if you are an RPM-enabled distro, it should have YUM on it. If it doesn’t install it and use it. YUM appears to be far more flexible and extensible than RPM and is now my install of choice.

What do you think between the two? If there is something that I missed, by all means point it out here.

Be very careful when using a Linux command-line/SSH interface not to mistype, especially when you are the root user.

This is something that I am sad to say I have come across on more than one occasion at my job (server technical support). Tiny little mistakes can wreak havoc on your computer/server if you mistype while using the command-line/SSH.

The information below uses the following keyboard slang:

= backslash
/ = whack
. = dot

Find these Keyboard Slang and more at codejacked.com

For all you Windows users out there who just happen to be reading this, there is a world of difference between “whack dot” /. and “dot whack” ./ In Linux, your root directory is labeled as “whack” / Thinks of this like your C: Drive on your Windows machine. Everything is relative to root. For example, if the path to a file on Windows was C:\folder\sub-folder\file , it would be /folder/sub-folder/file on a Linux machine. Yes the slashes point the other way from Windows to Linux: Windows uses “back slashes” \ and Linux uses “whacks” / If a file/folder location starts with a “whack” / , it means “from the root directory”. When dealing with file locations, the “dot” . means the files in the current/selected directory. So, literally “whack dot” /. means “all the files in the root directory” since the path begins with the “whack”; while “dot whack” ./ means “all the files in the current directory” since the path begins with the “dot”.

“Why bring this up?” you may be asking. Because you can cause a world of hurt if you mix up the two. Say for instance you want to delete all the files/folders in the current directory, a legitimate use. The correct command would be rm -R ./ The -R means “recursive”, meaning delete all files in any folder you come to, and then delete the folder, since only empty folders can be deleted on Linux. Or say for instance you needed to change the ownership of all the files/folders in the current directory. Again, the correct command would be chown -R user:group ./ This would set all files in, and below, the current directory to a user of user and a group of group. Those of you who have been following along can see where I’m going with this. If you mistakenly typed “whack dot” /. instead of “dot whack” ./ you just deleted all the files (recursively) starting at the root directory, or basically everything on your computer. Likewise with the chown command, you would’ve just changed the user and group for every file (recursively) starting in the root directory. Since certain services have to be run by specific users, this will cause problems.

Now luckily, the rm command for instance, is usually set as an alias to the command rm -i which means “prompt before removing each file”. However, if you think you know what you’re doing and decide to use the -f switch, this forces removal with no prompt. Therefore, if you leave off the -f when using rm , you’ll be prompted before removing any files, which may save you time, money, headaches, and in some cases, your job. Plus, for those of you who don’t know, unlike Windows, there is no “Recycle Bin” on Linux. Once you delete something, it’s gone for good. You can’t get it back.

There are plenty of other situations where a simple misspelling can cause all sorts of problems, especially when it comes to using switches (like the -f, -i or -R listed above), these two are just the most common mistakes I see. The bottom line is, especially when you’re logged in as the root user, just be careful when your working via command-line. Take 2 seconds to review your command before you hit “Enter”, because once you do, there’s no going back. If there is (going back), it’s not fun, it’s not easy, no one wants to do it, it will waste your time, and it will cost you money.

How about you? Have you ever “fat-fingered” something like this and caused problems? Post yours below.