Cut down on Linux command-line typing with these 10 handy bash aliases

What is an alias?

An alias is basically a shortcut for a command you place in your ~/.bashrc file. Aliases cut down on typing and can save you from having to look up a command. (If your memory is like mine, this can be a real boon!)

Aliases are set up near the bottom of the of the .bashrc file. You’ll see a commented-out section that indicates where you should put them. The format of an alias is:

Alias NICKNAME='full command here'

The keyword alias must be used. The nickname is what you will type at the command line. Make this nickname easy to remember. The = sign must also be used. After the = sign, you enter the full command, including flags and switches, enclosed in single quotes. Once you are done, save the .bashrc file and open up a new terminal. I always find it best to leave the original terminal window open in case there are problems. In the new terminal, type the alias nickname and the command will run.

To get you started, I’ve compiled the following list of aliases I have used over the years to help make my command-line experience a bit easier.

#1: The ssh alias

This one should be a no-brainer for those of you who frequently secure shell into particular boxes. For this I add an alias like so:

alias server_name='ssh -v -l USERNAME IP ADDRESS'

Just change server_name to a memorable name for the server. Then, change USERNAME and IP ADDRESS to suit your needs.

#2: The ls aliases

Some distributions don’t include some of the handier ls commands. Generally, I like to see full listings instead of just filenames. For that I always include this alias:

alias ll='ls -l'

Another handy ls alias is this:

alias la='ls -a'

#3: The rm safety net

I can’t tell you how many times I have “rm’d” a file I shouldn’t have “rm’d”. To avoid this, I add this alias:

alias rm='rm -i'

Adding the ‘-i’ flag it forces rm into interactive mode, which will ask you whether you’re sure you want to remove a file.

#4: The more useful df command

This handy tool tells you how much space you have left on a drive. Only thing is, if you run the command by itself it replies in 1K blocks. Most people would prefer to see this in terms of MB. To make that happen, add this alias:

alias df='df -h'

Now, every time you run the df command, the information will be returned in a human-readable format.

#5: The nonstandard Firefox

Many times, I install Firefox in strange directories (or have more than one version of Firefox installed for testing purposes). For this, I will add an alias to start the correct Firefox. Say, for example, I have the beta of the newest, upcoming Firefox release installed, as well as the current stable Firefox. They are both installed in my home directory in different subdirectories. I will then add two aliases like so:

alias ff1='/home/jlwallen/firefox/firefox'

alias ff2='/home/jlwallen/firefoxb3/firefox'

Now I can start the stable firefox with ff1 or the beta with ff2.

#6: The bookmark alias

Speaking of Firefox, let’s create an alias to open up it to a specific URL:

alias fftr='/home/jlwallen/firefox/firefox http://www.techrepublic.com'

This alias will open Firefox directly to the TechRepublic Web site.

#7: The constant editing of a file

There are certain files that I am constantly editing. For instance, when I used Enlightenment E16 (I now use E17), I was frequently editing the menu file ~/e16/menus/user_apps. Instead of constantly opening up a terminal and entering nano ~/.e16/menus/user_apps, I used an alias that allowed me to type emenu and start editing. I used this alias:

alias emenu='aterm nano -e ~/.e16/menus/user_apps'

Now, I just enter the command emenu (or I can enter that in the run command dialog) to open up this file in an editor.

#8: The apt-get update

There are numerous ways to use an alias to help you with apt-get. One of my favorite is to add this alias:

 alias update='sudo apt-get update'

I only need to enter update and will be prompted for the sudo password. You can modify this to suit your frequent apt-get needs.

#9: The rpm batch install

I like to do a lot of batch installing with rpm. I will typically dump a bunch of rpm files into an empty directory (created for this specific purpose) and run the command rpm -ivh ~/RPM/*rpm. Of course, an alias makes this even easier:

alias brpm='rpm -ivh ~/RPM/*rpm'

You have to create the ~/RPM directory and enter the root password for this to work.

#10: The long, arduous path

There are some paths that I often change to that seem to take eons to type. When I was working on the Afterstep window manager, I had to constantly change to the ~/GNUstep/Library/AfterStep/start to edit menus. After a while, you get tired of typing cd ~/GNUstep/Library/AfterStep/start just to get to the directory. So I added an alias like so:

alias astart='cd ~/GNUstep/Library/AfterStep/start'

Naturally, you can change that to fit your needs. This will save you a lot of typing.

So there you have it: a few simple bash aliases that will ease the load on your fingers. You can modify them to suit you, and they’ll give you a good start on creating your own handy bash aliases.

: Password cracking made easy

One of the basic tenants of information security is to ensure that systems use strong passwords, namely those of a certain length that mix letters, numbers and other special characters. One way to determine if your password is strong is to type it into a password checker, like Microsoft's Password Checker. The software giant's tool checks for sufficient length and complexity.

These more complicated passwords are considered "strong" because they take a longer time to crack than shorter, easier-to-guess passwords. But even strong passwords can be cracked in seconds using an open source tool called Ophcrack.

Ophcrack is an extremely fast password cracker because it uses a special algorithm called rainbow tables. Brute-force cracking tools typically try thousands of combinations of letters, numbers and special characters each second, but cracking a password by attempting every conceivable combination can take hours or days. Rainbow tables pre-computes the hashes used by passwords, allowing for a speedy password lookup by comparing the hashes it has, instead of computing them from scratch.

Thinking of it another way, someone else has already generated the password hashes for millions of potential passwords using the same algorithm as Windows XP and Vista. Ophcrack simply loads the megabytes of hashes it already has and compares the password hash in Windows against its giant database. When it finds a match, Ophcrack reveals the password in plain text.

Ophcrack works on LAN Manager (LM) and NT LAN Manager (NTLM) hashes, and has rainbow tables available for cracking Windows XP and Windows Vista passwords. It comes with a slick GUI and runs on Windows, Linux/Unix, Mac OS X, or from a bootable LiveCD. Ophcrack has the ability to obtain password hashes from the Security Accounts Manager (SAM), the registry database that Windows uses to store protected user passwords.

Ophcrack is not malware and has its legitimate uses. For instance, most Windows password-recovery tools will substitute a new password in place of a lost one, but knowing the actual password may be useful in unlocking other archives found during a forensics investigation. Additionally, testing a known password against Ophcrack, and besting the rainbow tables, can help validate that the password is extremely strong.

However, one of the tools Ophcrack uses to access the SAM is pwdump, which many virus scanners will flag and quarantine as malware during installation because of its ability to create surreptitious remote connections used for spiriting out data. Ophcrack requires pwdump in order to dump the hashes in the SAM, so its association with pwdump may present some ethical hackers with an uncomfortable level of risk.

How do uninstall Microsoft Internet Explorer 7?

If your installation of IE7 was successful and uneventful, then uninstalling it is relatively simple process. The following steps will uninstall IE7 and restore IE 6.

• Click Start, and then click Control Panel.
• Click Add or Remove Programs.
• Scroll down to Windows Internet Explorer 7, click it, and then click Change/Remove.

If for some reason Windows Internet Explorer 7 does not appear in the Add or Remove Programs, you should:

• Open Windows Explorer
• Click Tools | Folder Options
• Click the View tab
• Make sure the radio button next to Show hidden files and folders is on
• Click OK
• Click Start, and then click Run
• Type: %windir%\ie7\spuninst\spunins.exe into the text box and click Enter

Specified user account

In some cases, you may get an error message when you try to uninstall IE7 that says you cannot uninstall from a specified user account. To get around this check you will have to edit the Windows Registry.

Warning: Editing the Windows Registry incorrectly can cause the Windows operating system to stop functioning completely. This is an advanced operation and you are encouraged to back up the Windows Registry before you attempt any editing of the file. You have been warned.

Bypass the user account check with this Windows Registry edit:

• Click Start, click Run, type regedit, and then press ENTER.
• Navigate to HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer.
• Right-click the Internet Explorer key, click New, and then click DWORD value.
• Type InstalledByUser as the name, and then press ENTER to finish creating the new registry value.
• Try to uninstall Internet Explorer 7 again.