About a month ago I was on IRC with Jim and some of his contributors, and had this crazy idea that I'd volunteer to write an article. I'm not sure where I came up with this idea, because I'd been using FreeBSD for around a month, and am still quite a newbie. Somehow it was agreed upon that I would write an article on a subject I didn't know about yet, but wanted to learn. I settled on shell scripting, which I will now attempt to explain.

Now, close to a month later, panic is setting in. I've got one paragraph of that article done, and still don't have a clue how to write shell scripts. So I guess I'll have to write about what I do know, the raw basics, and fill in some of the more advanced concepts in another issue.

A shell script is a text file that contains a series of commands to be executed. You can create quite complicated shell scripts, but for now I'm just going to discuss the steps involved in making a very simple one.

The first step is to create the text file. You can use whatever editor you are comfortable with. I prefer vim myself:

	% vim ~/bin/startrc5
  

I'm not quite sure why, but the sources I read said that shell scripts should begin with the line:

        #!/bin/sh
  

(Actually, that only applies to Bourne shell scripts. Unless you have a good reason, you should probably stick to using the Bourne shell.)

Then the text of your script:

	rm /usr/local/d.net/exitrc5.now
	/usr/local/d.net/rc5des
  

And that's it. Save the file, and mark it as executable:

	% chmod a+x ~/bin/startrc5
  

(In case you were wondering, ~/bin stands for the bin directory in your home directory. In my case, ~/bin would translate to /usr/home/jshafer/bin. So there should be a directory called bin in your home directory, and it should be a part of your path.)

Next, if you are using csh or tcsh you either need to log off and log on again, or type the command:

	% rehash
  

And that's all there is to it. You now have a text file in your ~/bin directory that contains:

	% cat ~/bin/startrc5
	#!/bin/sh
	rm /usr/local/d.net/exitrc5.now
	/usr/local/d.net/rc5des
  

There is much more to learn, and my little shell script here may not be that good, but it demonstrates the basics.

Shell Scripting References and Links

-John

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