cat

This is one of the most flexible Unix commands. We can use to create, view and concatenate files. For our first example we create a three-item English-Spanish dictionary in a file called "dict."

   % cat >dict
    red rojo
    green verde
    blue azul
 
  %

stands for "hold the control key down, then tap 'd'". The symbol > tells the computer that what is typed is to be put into the file dict. To view a file we use cat in a different way:

   % cat dict
    red rojo
    green verde
    blue azul
  %

If we wish to add text to an existing file we do this:

   % cat >>dict
    white blanco
    black negro
     
  %

Now suppose that we have another file tmp that looks like this:

   % cat tmp
    cat gato
    dog perro
  %

Then we can join dict and tmp like this:

   % cat dict tmp >dict2 

We could check the number of lines in the new file like this:

   % wc -l dict2
8

The command wc counts things --- the number of characters, words, and line in a file.