Hints for Using Program Examples Under Unix

A very intelligent turtle
Found programming UNIX a hurdle
The system, you see,
Ran as slow as did he,
And that's not saying much for the turtle.

Compilation:

Suppose the Fortran code is stored in the file progX.f. The command

make progX

makes the executable called progX (provided that you do not have a file called makefile or Makefile in the same directory). It can be executed by just typing the executable name, exactly as any other Unix command.

Output redirection:

If a program (or any Unix command) progX writes to the standard output (screen), the output can be redirected to a file outfile by typing

progX > outfile

grep and friends:

The command grep is very useful to extract information from output files. It is a standard Unix command that extracts lines from the given file containing given string. For example, to extract all energy values, stored in the file outfile, just type

grep Ener outfile

and you will have them on the screen. To store them in the file enerfile, do this:

grep Ener outfile > enerfile

Programs like sed or awk can be very useful for producing tabulated data suitable for plotting programs.