Paths
UNIX operating systems follow a hierarchical directory structure. Before I launch into an explanation of how the UNIX file system works, remember that in UNIX, everything is a file. Everything. Even outputs, commands, and devices are files.
File Systems
File systems are how your files are arranged in your computer.
The UNIX file system looks like a tree, where everything starts in the root directory, which is just written as a forward slash: /. Basically, directories (also known as folders in other OSes) hold files and subdirectories, which hold even more files and subdirectories, and so forth. This tree of directories (and files) is easily navigable as long as you know the path of what you’re looking for.
Paths
A path in the file system traces out the location of a file/directory from a given directory.
You separate directories with slashes which signifies if something is inside of something else. Remember, the very first slash is also a directory: the root directory. For example, /home/john/Documents/DevLeague/helloworld.py is the path detailing the location of the file “helloworld.py”. It is in the DevLeague directory, which is in Documents, which is in john, which is in home, which is in / (the root directory).
A special pathname is ~ (tilde). ~ stands for /home/user/. Note that user is not literally “user”, but the name of the user profile (which is junior in our computers at Academy). When you first open your terminal, you are placed in your user’s home directory ~ by default. It holds everything a normal user would use, the Desktop, Documents, Downloads, Pictures, etc. directories. In the above path example, we didn’t have to write out that entire path. Instead of having the /home/user, we could’ve just written ~/Documents/DevLeague/helloworld.py.
When writing out paths for anything (such as arguments), you can write them out as absolute or relative paths.
Absolute Paths
Absolute paths point to the file/directory regardless of the current working directory (the directory you are in). It always includes the root (or ~). The paths in the examples above are written as absolute paths.
Relative Paths
Relative paths point to the file/directory starting from the current working directory. You write them without the root /, and just start off as if it’s continuing from where you currently are in your terminal. For example, if I am in ~/Documents and I wanted to access the “helloworld.py” file, I could just write out DevLeague/helloworld.py.
Click here to complete the experiential learning exercise “Tracing paths”.
Before moving on to the next reading, click here to complete the experiential learning exercise “Terminus”.
Then, click here to move on to the final reading of this module, “Basic Bash”.