11.2 Text Editors: emacs, vi, pico, etc.

There are many different ways to edit files on Unix, similarly on Windows. Under Windows there are programs like notepad, wordpad, or the DOS propmt's edit command. Under Unix the two most popular editors are vi or vim and emacs or xemacs. My preference is emacs but some hard-core Unix-types prefer vi. A third editor is pico. Pico is really easy to use but not very powerful. Use a text editor to type in the following code and save it with the name power3.f90. If you need help, ask!

PROGRAM power3   ! program to calculate 3rd power of 5
  IMPLICIT NONE
  INTEGER :: a, b
! set variable `a' to equal 5, take the cube and write answer
  a = 5
  b = a*a*a
  WRITE(*,*) a,b
END PROGRAM power3

After typing in the program, save it, and get back to the command prompt. (If you are using pico, exit and saving using Ctrl-X. If you are using emacs, use Ctrl-X Ctrl-C.) Now, you have the source code for a program. To turn that code into something the computer can execute, it must be compiled. In this case we will use the Fortran compiler called f90. To compile your code, type f90 power3.f90. (If you didn't use the name power3.f90 for your file, replace it with the appropriate filename.) This creates a program named a.out. Now that an executable has been created from the source code, the computer can run it. Type a.out to run the program. insert day 2 of Emacs here. To edit a file with emacs (or create a new file), type emacs filename where filename is the name of the file you want to edit/create. The emacs ``window'' will appear. The bottom line of the window is called the ``minibuffer''. The minibuffer is where you emacs commands are displayed as you type them. The main part of the window is where the current ``buffer'' is displayed. You can think of the buffer as simply the current open file that you are editing. When you save the buffer, you save the file. Here are some of the most common emacs commands:

Ctrl-x Ctrl-c	exit
Ctrl-x Ctrl-s	save
Ctrl-x Ctrl-f	save to different file name
Ctrl-g	cancel command
Ctrl-k	delete from here to end of the line (and copy to the
	``clipboard'' for later ``pasting''. In emacs-speak, the
	selection is copied to the ``kill ring'' where it can
	later be ``yanked'')
Ctrl-y	``Paste'' (``Yank'' in emacs-speak)
Ctrl-x Ctrl-v	Oops, opened the wrong file--open this one instead
Ctrl-x k	Exit out of the current buffer but keep Emacs open