Working with Files

Commands

The following commands are commonly used commands for working with files.

cat         # show the contents of a file
more        # show the contents of a file, forward scrolling/jumping
less        # show the contents of a file, forward and backward scrolling
cp          # copy a file
mv          # move a file, rename a file
wget        # download stuff (sudo apt install wget)
xdg-open    # open a file or url in its default application

Example

Navigate to Desktop and create a books and music directory
```
cd ~/Desktop
mkdir books music
```

Navigate into the newly created books directory and download a book

cd books
wget https://www.gutenberg.org/cache/epub/98/pg98.txt 
ls

Rename the book

mv pg98.txt a-tale-of-two-cities.txt
more a-tale-of-two-cities.txt

Download another book

wget https://jcoriell.github.io/csc222/files/cnbc.txt
more cnbc.txt

Navigate to the music directory from the books directory and download a song

cd ..
cd music
wget https://jcoriell.github.io/csc222/files/mbe.mp3
xdg-open mbe.mp3    # open it with the default application for the system

Text Editors

vim (Vi - Improved)

steep learning curve, but frequent users love it
will make you better that everyone else
can learn using the command vimtutor

Open with the command: vim [filename]

Vim Modes:

insert      - i to activate, escape to back out

replace     - r to enter replace mode, use it to write over text instead of inserting text
            - escape to back out

visual      - v, V, or ctrl+v to activate character, line, or block visual mode 
            - used to select text and apply commands to that text
            - ex: copy, cut, replace, indent, search, and more...
            - escape to back out 

command     - : to activate. Some common commands:
            - w to save
            - q to quit
            - wq or x to save and quit
            - q! to quit without saving
            - e [filename] to open a file
            - saveas [filename] to save the file as a new name
            - [an integer] to jump to a line

Example

Use the following two commands to create a file somewhere on your system.

cd ~/Desktop/programs               # navigate to a folder to complete the example in
vim random_number_generator.py      # open a file (it is ok if the file doesn't exist yet)

At this point vim should have opened.

Type i to enter insert mode and type the following code.
```
import random

print(random.randint())
```
Now hit escape to exit insert mode.
Move the cursor to the beginning of the word randint
Hit v to enter visual mode.
Use the e key to go to the END of the word (b goes to the Beginning)
Use the c key to CHANGE the selected text to random. (we are replacing randint with random)

At this point the python code should look like this:
```
import random

print(random.random())
```
Use escape to exit insert mode.
Use : to enter command mode.
Type wq and hit enter to save and exit.
If you’d like to run the code, use the following command:
```
python3 random_number_generator.py
```

Tip

It is recommended at this point that you run the vimtutor command if you’d like to learn more about using vim.

Nano

a simple to use terminal based text editor
little to no learning curve

Example

In this example, we create a file and add “hello world” to it using nano.

Run the following commands

cd ~/Desktop/programs       # navigate to a folder to store a file
touch helloworld.py
nano helloworld.py

At this point, the file should be open. Type print("hello world") on the first line.
Type ctrl + x to be prompted to save and close.
Run cat helloworld.py to see the contents.
Run python3 helloworld.py to run the file.

Reference Files

Reference

A Tale of Two Cities

Cajun Night Before Christmas

Meow