Perl for Web Site Management

A Suitable Text Editor

You’ll need one more tool in order to begin working magic with Perl: a text editor.

Actually, you’ll probably want two of them because you will be writing your Perl scripts in two different places. Sometimes you will write them on your desktop PC (or Mac), then will transfer them to your ISP’s Unix server using an FTP program (like WS_FTP for the PC, or Fetch for the Mac). Other times you will create your scripts right there on the Unix machine using a Unix text editor.

Tip

Because FTP is an unencrypted protocol, it is prone to the same security problems as Telnet is. For that reason, you may wish to investigate using an encrypted protocol for your file transfers. Martin Prikryl’s WinSCP (http://winscp.vse.cz/eng/) offers a nice Windows implementation of the secure scp protocol (which uses ssh for security) to do file transfers. For Mac users, the aforementioned NiftyTelnet (http://andrew2.andrew.cmu.edu/dist/niftytelnet.html) also does scp file transfers. (Mac users running OS X can also use the scp command-line program directly.)

The traditional text editors used in the Unix environment are emacs and vi (the latter pronounced “vee-eye”). Both are extremely powerful and full-featured. Both can also be a bit intimidating for beginners. Because of that, I’m actually going to focus on a simpler (albeit less powerful) editor called pico for this book’s text-editing-under-Unix examples. If pico is not available on your system, you may need to buckle down and learn emacs or vi whether you want to or not. In that case, see The Traditional Unix Editors: emacs and vi later in this chapter.

The Traditional Unix Editors: emacs and vi

Eventually, if you spend enough time editing text files under Unix (or right away, if your Unix server happens not to have a simpler editor like pico) you will probably find yourself needing to learn one of the two standard programmer’s editors typically used in that environment: emacs or vi.

The emacs editor is arguably the easier of the two for a beginner to pick up. For one thing, it is modeless, meaning what you type appears as text in the document you are currently editing, while you enter special keystroke sequences (typing the Ctrl key in combination with some other key, for example) to perform other commands, like saving the current document or exiting the editor.

You may be able to start up the emacs editor just by entering emacs at the Unix command line. In that case you will probably get a help screen that outlines some of the basic commands, perhaps even giving you access to a tutorial. More information is available at the program’s web page, http://www.gnu.org/software/emacs/.

The vi editor has two principal virtues. The first, and most significant for the current discussion, is that it is the lowest-common-denominator editor in the Unix world, making it (almost) certain that it will be available on any Unix computer you find yourself using. The second is that, for an experienced user, it is tremendously powerful, allowing very rapid text editing.

The main downside to vi is that it achieves this power via a moded approach, in which particular keystrokes do different things depending on what mode the program is currently in (command mode, insert mode, or ex mode). This ends up being relatively difficult to learn, and even once learned, relatively awkward to use until you’ve practiced a fair amount.

A nice vi tutorial is available at http://www.eng.hawaii.edu/Tutor/vi.html.

Whichever tools you end up using, the bottom line is that you’re going to need some way to edit text on both your desktop computer and the Unix server. Editing in each environment will have its pluses and minuses. Writing scripts on your PC will probably feel more familiar to you, at least at first. You can use your mouse for selecting text, and can work on your script when you’re not actually connected to the Internet. The downside is that you’ll have to use an FTP program to move your script to the Unix server every time you make a change to it. Writing your scripts directly on the Unix machine lets you avoid the file-transfer step. You’ll have to gain at least a passing familiarity with a Unix text editor, though, which means learning a bunch of keyboard commands to move around within the file, since you won’t be able to do things with your mouse.

I edit on the Unix server for small scripts and on my local PC for larger projects. You may have already dealt with this issue when deciding how to create HTML files for your web site, assuming you are coding your HTML by hand, rather than using an HTML authoring program. There’s one important difference, though: if you’re creating the scripts on your local PC or Mac, then uploading them to your Unix server via FTP, you must make the FTP transfer in text mode (sometimes called ASCII mode, depending on your FTP program). This typically doesn’t make any real difference when uploading HTML files, but it matters a lot for Perl scripts: if you upload your Perl scripts in binary mode, they probably won’t work. This is because each type of computer (Unix, PC, and Macintosh) uses a different sequence of characters to mark the end of a line of text. Transferring in ASCII mode causes the FTP program to convert the line endings for you on the fly.

You may be inclined to try to use a word processor program (like Microsoft Word) to create and edit your Perl scripts when you’re working on the local PC, but I would advise against it. Because they have been optimized for the specific task of outputting attractive paper-based documents, modern word processors are a poor choice for editing straight ASCII text. You’ll be much happier with something that doesn’t try to convert all your straight quotes to curly quotes and flag all your Perl syntax as misspelled and ungrammatical. On the Windows side, I’ve been very happy with a freeware program called EditPad (available at http://www.editpadpro.com/editpadclassic.html); a shareware program called UltraEdit (http://www.ultraedit.com/) is also very good. On the Mac side, a program called BBEdit Lite (see http://www.barebones.com/) is very popular.

This chapter has presented only a shallow introduction. If you are anything like me, you will be able to continue to learn more about choosing web hosting vendors, working in the Unix shell, troubleshooting network problems, and using text editors for many years to come. With the information presented here, though, you should be able to take your first steps and begin doing useful work. In particular, you should now be ready for the next chapter, in which you get your first exposure to the Perl programming language.