The file system

The file system provides a structured way to name and organize files, typically using a hierarchical directory structure. Below there are some of the basic commands to move around.

Print Working Directory

The pwd command prints the current working directory path.

pwd

/users/home/us01234

Change Directory

Use cd to navigate between directories:

• cd directory_name: Move into a specific directory
• cd ..: Move up one directory level
• cd ~: Go to home directory

Location abbreviations

• ~ tilde, your home folder (also $HOME)
• . dot, your current working folder
• .. dot dot, one folder up or back from here
• - dash, the folder you were most recently in
• / root, the folder containing the whole file system
• if we type cd alone it will always take you back to your $HOME

List Directory Contents

The ls command lists files and directories in the current location. Common options include:

• ls -a: List all files, including hidden ones
• ls -l: Long listing with details like permissions and timestamps

us01234@myMacBook course-cli % ls                                     

README.md       answers         data            requirements.txt
_extensions     appendix        index.qmd       style.scss
_quarto.yml     assets          pages

us01234@myMacBook course-cli % ls -a                                    

.               .gitignore      appendix        requirements.txt
..              README.md       assets          style.scss
.DS_Store       _extensions     data
.git            _quarto.yml     index.qmd
.github         answers         pages

You can also use list filtering for specific file names or patterns.

us01234@myMacBook course-cli % ls -la *.txt

-rw-r--r--@ 1 gx18744  staff  15 26 Sep 02:06 requirements.txt                                   

Special characters

• * wildcard (any characters): ls *.txt
• ? wildcard (single character): ls file?.txt
• [] character set wildcard: ls file[123].txt
• {} brace expansion: echo {1..5}