Create Files and Directories

reading

We will loosely follow the Software Carpentry Working with Files and Directories lesson from The Unix Shell

Let’s start in ~/shell-lesson-data/exercise-data/writing:

cd ~/shell-lesson-data/exercise-data/writing

Making a new directory

We want to put a new document here (our thesis) and we will organize it in its own sub-directory. The command to make a new directory is mkdir (for make directory). We can do:

mkdir thesis

and then change directory into it and print the current directory:

cd thesis
pwd

This should show something like:

/home/mzingale/shell-lesson-data/exercise-data/writing/thesis

Tip

Don’t use spaces in directory or file names. This makes navigation difficult.

Likewise, don’t start a directory or filename with a -, since most commandline tools will interpret this as an option / flag.

Creating a new file

We already did a quick example of creating a hello.cpp earlier, using the nano editor. Let’s create a new file now, called thesis.txt:

nano thesis.txt

The editor will open with an empty file. Write a few sentences, like the screenshot below

Fig. 1 The nano editor with our thesis.txt

Now save it using the combination Ctrl-O to write, and the exit with Ctrl-X.

Try it…

Sometimes we need a file to exist, but we don’t care if there is anything in it. We can use the touch command for this—if a file with the name does not exist, it will create it as an empty file.

touch topics.txt

We can see the file sizes by using the -l flag to ls:

ls -l

This will show something like:

total 4
-rw-r-----. 1 mzingale mzingale 75 Jan 19 13:08 thesis.txt
-rw-r-----. 1 mzingale mzingale  0 Jan 19 13:16 topics.txt

There are a lot of columns here, but the 5th column gives the size in bytes for our file.

Looking at our file

If we do ls, then we’ll see our file.

If we want to see the contents of the file from the command line, we can use the cat command:

cat thesis.txt

Tip

For very long files, the output will scroll past our screen without stopping. Instead we can use the more command, which acts as a pager. We’ll see this more in a bit.

Summary

We learned the following commands:

• mkdir : make a directory

• nano : a basic text editor

• touch : update a file’s timestamp (and create an empty file if it does not exist)

• cat : display the contents of a file (it has other uses which we’ll explore later)

Exercises

Try it…

From your home directory, create a directory / file structure that looks like:

project
├── code
├── data
│   ├── experiment-01.txt
│   ├── experiment-02.txt
│   └── experiment-03.txt
└── results