Linux Command Line Aliases

As a data guy, I do an awful lot of work from the command line.  I get so much more done that way.  And if your experience is anything like mine, you may have found that there are a number of moderately complicated Linux shell commands that are extremely useful, but you don't use them often enough to type them from memory when you need them.  So instead you rummage through that pile of papers on your desk (or the files on your hard drive, or the posts on your blog, or the search results from Stack Overflow, etc., etc.) looking for "that one command" that was "just what you needed" when you were in a similar situation seven and a half months ago.  What a waste of time!

Or maybe you can remember the command, but it's long and tedious, and you just hate typing it every time you need to use it.

Enter command line aliases!

Aliases are super handy.  They allow you to take a long/arcane/obscure/tedious command (like (IFS=$'n'; du -s -BM `find -type d | egrep '^./[^/]+$'` | sort -nr | less)) and replace it with a shorter label that is easier to remember---(an alias)---like "dud" (disk usage directories).

Next I'll show you how to set up aliases and give a few examples of my favorites.  I'm using the bash interpreter on Ubuntu Linux, so I'll assume that you're using it, too.  It shouldn't be hard to adapt these instructions for other interpreters or distributions.

Configuring Aliases

There is a file called .bashrc in your home directory.  You can edit it with the following command line:

{editor} ~/.bashrc

replacing {editor} with the name of your editor of choice (emacs, nano, vim, etc.)  After that, it's simply a matter of adding alias lines to the end of the file.  Each alias line has the following format:

alias {label}='{command}'

where {label} is the short label that you'd like to type instead of {command}.

(NOTE: Single quotes ensure that characters that are normally special to the shell---$, !, #, etc.---are not interpreted in any special way.  You often need to put {command} in single quotes for everything to work properly.  But beware that using single quotes can create some headaches when your command relies on single quotes as well.  You can't just escape a single quote (') within single quotes.  See the top answer for this question at Stack Overflow for help on embedded single quotes.)

That's it!  Just close your terminal window, open a new one, and you should now be able to use your new aliases to run those commands that are hard to remember or tedious to type!

But wait.  It's entirely possible that six months from now (or next week, for that matter) I won't remember the original command or the alias I just created.  By typing "alias" on the command line, you'll get a list of the currently active aliases that you've created.

Alias Examples

Now for a few examples of aliases in action.  The following are some of my favorites.

dud -- disk usage directories

(NOTE: This alias is a good example of using embedded single quotes.  It's not pretty, but it was the only way I found to get it to work.  Anyone know of a better way to do this?)

alias dud='(IFS=$'"'"'n'"'"'; du -s -BM `find -type d | egrep '"'"'^./[^/]+$'"'"'` | sort -nr | less)'

When I'm cleaning up my hard drive, doing backups, reorganizing directories, etc., I often want to know how much space a particular directory takes up.   dud will show a list directories that are children to the current directory and how much space each directory takes up.  It sorts the list in descending numerical order by the amount of storage space each directory uses.

aaron@ajvb:~$ dud
6101M   ./Dropbox
2827M   ./devel
296M    ./tika
161M    ./.cache
154M    ./.m2
124M    ./.cpan
117M    ./.dropbox
88M     ./.mozilla
50M     ./.dropbox-dist
44M     ./.config
10M     ./R
10M     ./.local
9M      ./Downloads
...

duf -- disk usage files

alias duf='(IFS=$'"'"'n'"'"'; du -s -BM `find -type f | egrep '"'"'^./[^/]+$'"'"'` | sort -nr | less)'

Similar to dud, this alias shows the space taken up by each file in the current directory.

aaron@ajvb:~$ duf
14M     ./Product_Report.xls
2M      ./Spending Vis.ai
1M      ./Ward Activity August 8th.docx
1M      ./.dropbox
1M      ./content.xml
1M      ./Combined-Data.xlsx
1M      ./AJ Statement.pgp
1M      ./Activity Sigh Up.docx
1M      ./Activity Flyer Large.pdf
1M      ./Activity Flyer Large.docx
...

Traversing Upwards through the Directory Hierarchy

Sometimes in my projects I find myself really deeply entrenched in the folder hierarchy.  There is nothing worse (OK, there are probably worse things) than having to cd ../../../../.. your way towards some other folder higher up the tree.  Here are a couple of aliases that help with that.

alias .='cd ..'
alias ..='cd ../..'
alias ...='cd ../../..'
alias ....='cd ../../../..'
alias .....='cd ../../../../..'

Or, if you prefer even less typing, you could use the following instead.

alias .='cd ..'
alias .2='cd ../..'
alias .3='cd ../../..'
alias .4='cd ../../../..'
alias .5='cd ../../../../..'

Conclusion

Aliases are awesome, and customizing the command line interface gives you some serious satisfaction and some geek cred to boot.  I'll probably add to this list over time. In the meantime, what are some of your favorite command line aliases? Feel free to share them in the comments below.