Editing Files¶
Overview¶
This lesson will introduce you to using a text editor in the command line shell.
Prerequisite¶
In order to conduct this lesson you should have knowledge of
- How to use a shell (see Shell)
- Log into your FutureSystems shell (see Use of FutureSystems)
Description¶
When we say, “nano
is a text editor,” we really do mean
“text”: it can only work with plain character data, not tables,
images, or any other human-friendly media. We use it in examples
because almost anyone can drive it anywhere without training, but
please use something more powerful for real work. On Unix systems
(such as Linux and Mac OS X), many programmers use Emacs or Vim (both of which are completely
unintuitive, even by Unix standards), or a graphical editor such
as Gedit. On Windows, you
may wish to use Notepad++.
To follow along, please log into your account on india
.
Let’s start by creating a directory in which to work:
$ mkdir editors-lesson
$ cd editors-lesson
$ ls
Printing the list of directory contents with ls
shows that this is
empty. Let us open a file to write some text:
$ nano fish.txt
Note that this changes the window a bit.
We used to be in the shell, which is an interactive program.
We are now presented with a text editor, which is another interactive program.
Interaction with the editor is also done using the keyboard, though
the commands are different than in the shell.
Each editor will have a different interface.
In the case of nano
, the available commands are shown at the bottom:
The format for nano
commands is caret,character, then description.
The caret represents the control
key, the next character is the
character to press (X, O, G, etc), and the description indicates
the function of the command
The important commands are:
- ^X
to exit, optionally saving the file
- ^O
to save the file
- ^G
to get help
If you are not sure what to do in nano, look to the bottom for the available commands.
Let start writing some text:
one fish
two fish
red fish
blue fish
At this point we wish to save the file and exit.
Press ^O
to write, then ^X
to exit.
We can now ls
again and see that the file now exists:
$ ls
fish.txt
Print the contents to screen using cat
:
$ cat fish.txt
one fish
two fish
red fish
blue fish
Exercises¶
Exercise I¶
Edit fish.txt
and append the following text:
Black fish
Blue fish
Old fish
New fish.
This one has a little star.
This one has a little car.
Say! What a lot
Of fish there are.
Exercise II¶
Create a new file eggs.txt
and write the following text:
Do you like
green eggs and ham?
I do not like them,
Sam-I-am.
I do not like
green eggs and ham.
Save the file and print the directory listing. How many files are there? Count the number of lines, words, and characters in each file without opening them.
Exercise III¶
To cleanup this lesson, remove the files and directory you created.