This is a very hands-on post, since I thought the last couple of ones (including the one I just threw away) was a bit high flying.
Here we go - I have grown into a bit of a statistics maniac, especially when it comes to my blog. I’m not getting better and I like it. :)
I now found myself in a situation where I simply wanted to count the number of files in my posts directory. In the terminal of my Mac.
Count’em
First I found a nice little combination of commands that did exactly that:
ls -1 | wc -l
Yeah, exactly. That doesn’t look to hard. And yes - I would never remember that either. My memory is excellent but very short.
Remember it
Luckily there’s a very simple little tool that can make commands like that easier to remember. You can create an alias with a name that’s easier to remember. Like this for example:
alias count='ls -1 | wc -l'
Sweet! Now I can go count in the current directory and get the number of files, i.e. posts. 977 by the way. Yes I’m proud.
Permanent it
However - should you close the Terminal window and then, tomorrow, open it again you will be sorry since the count command now is gone. This is a bit surprising and also disappointing.
Well the answer is, with OS X / Linux measures, relatively easy to fix. Open your ~/.bashrc file in a text editor (for example with sublime ~/.bashrc) and add your alias in the end of the file.
Like this:
alias count='ls -1 | wc -l'
Now you can close the Terminal, reboot your computer or what ever you fancy and the count command will still be present.
Parameterize it
Now I realized that I actually have to cd into the directory I wanted to check. And apparently alias doesn’t support parameters to be passed.
But that’s easy to fix… Convert it to a function like this:
function count() { ls -1 "$1" | wc -l; }
The $1 is the first parameter passed to the function. The last ;-char is important, or you’ll get a syntax error.
This is good because now I can do, for example this:
count ./Projects/blog/marcusoftnet.github.io/_posts/
And see my glorious 977 (sorry) posts again. But I have to supply a parameter. It would be cool if it used the current directory is nothing was supplied. Well… that can be done like this:
function count() { ls -1 "${1:-.}" | wc -l; }
As everything Linux the commands are terse and super powerful, but basically the form is {parameter:option}. In the option part we give a - which translates to “if not supplied”, or default value. In our case it’s just the current directory, ..
Put that into your ~/.bashrc, save it and restart your Terminal. And now you can go:
marcus$ count
13
marcus$ count Projects/blog/marcusoftnet.github.io/_posts/
977
Lovely!
Summarize it
I love diving into stuff that I know little about. I will not make commands like this everyday but you never know when I (or you ^^) will look here again.