The commands in UNIX usually consists of only 2 or 3 characters. In order to list the names of the files in the present directory you use the command ls , or the more powerful ls -lFa , often abbreviated lls . Their names start with a dot alias lls 'ls -lFa' You can find the presently set aliases with giving the very simple command alias . You can list the contents of a file with the command cat followed by the file name. It is however often better with large files to use more , with which you can go forward and backward in the file.
Space gives one screen page forwards, b gives one screen page backwards, and q gives exit.
You move around in the file structure with the command cd area . You can edit the file with a system specific editor, with the UNIX standard-editors ex or vi or with the well known emacs . For Fortran 77 programs the file name is supposed to end with .f , for example prog.f . If you use the old fix form the ending .f is still valid. The name of a Fortran program unit can end with some other characters, like .for .