To execute basic commands is necessary to type the command name (full name
  or relative name).
Ex. 1:
$ pwd
/home/user

  To add arguments to the command, type them after the command id.
Ex. 2:
$ ls -a
. .. folder1 file1 file2
Ex. 3:
$ cat -T example_file1
  (...)

   To use the history feature, the user must type '!!'.
Ex.:
$ ls -a
. .. folder1 file1 file2
$ !!
Last command: ls -a
. .. folder1 file1 file2

   To redirect the output of a command, the user must type '>' 
   followed by the name of the output file after the command id. 
   And to redirect the input, the user must type '<' followed by 
   the name of the input file after the command id.
Ex.:
$ echo Hello World > hello_world.txt
$ cat hello_world.txt
Hello World
$ cat < hello_world.txt
Hello World

   The pipe command ('|') can be used to redirect the output of one command to the 
   next command. The input redirection can be used only with the first command of the pipe. 
   The output redirection, on the other side, can be used in any command of the pipe.
Ex. 1:
 $ cat example_file.txt
a
c -> I want this line
d
e
b
f
g
 $ cat example_file.txt | sort > sorted_example_file.txt | grep c
c -> I want this line
 $ cat sorted_example_file.txt
a
b
c -> I want this line
d
e
f
g