In operating systems, file paths specify the location of a file or directory within the file system hierarchy. There are two main types of paths: absolute paths and relative paths. Understanding these two's differences is crucial for navigating and managing files effectively.

1. Absolute Path

An absolute path is the complete path from the file system's root directory to the target file or directory. It provides an unambiguous location, regardless of the current working directory. Absolute paths always start from the root directory, which is represented by a forward slash (/) in Unix-like systems (Linux, macOS) or a drive letter (e.g., C:\) in Windows.

Characteristics of Absolute Paths:

Starts from the root directory.
Provides the full directory structure.
Does not depend on the current working directory.
Useful for specifying exact file locations in scripts or programs.

Examples of Absolute Paths:

Unix-like System (Linux, macOS):

/home/user/documents/report.txt
This path starts from the root (/) and specifies the exact location of the report.txt file in the documents directory under the user home folder.

Windows:

C:\Users\John\Documents\report.txt
This path starts from the C: drive and specify the exact location of the report.txt file in the Documents directory under the John user folder.

2. Relative Path

A relative path is a path that is relative to the current working directory. It does not start from the root directory but instead specifies the location of a file or directory in relation to where you currently are in the file system. Relative paths are often shorter and more convenient when working within a specific directory structure.

Special Symbols in Relative Paths

. (Single Dot): Represents the current directory.
Example: ./file.txt refers to file.txt in the current directory.
.. (Double Dot): Represents the parent directory.
Example: ../file.txt refers to file.txt in the parent directory.

Characteristics of Relative Paths:

It does not start from the root directory, i.e., no / in Unix-like system or C:\ in Windows at the beginning of the path.
Depends on the current working directory.
Uses special symbols like . (current directory) and .. (parent directory) for navigation.
Useful for simplifying file references within a project or directory.

Examples of Relative Paths:

Unix-like System (Linux, macOS):

If the current working directory is /home/user, the relative path to report.txt in the documents a directory would be:
documents/report.txt
To reference a file in the parent directory:
../otherfolder/file.txt

Windows:

If the current working directory is C:\Users\John, the relative path to report.txt in the Documents the directory would be:
Documents\report.txt
To reference a file in the parent directory:
..\OtherFolder\file.txt

3. How Systems Handle Drives

Each drive in the Windows operating system is assigned a unique absolute path. This means that every drive, whether the C: drive, D: drive, or any other drive, is identified by a specific path that distinguishes it from others. This structure allows users to easily locate and access files stored on different drives within the system.

However, unlike Windows, Unix-like systems do not have absolute paths for drives. Instead, they use a single-root filesystem (/), where different storage devices (like external drives or partitions) are mounted into directories within this hierarchy.

Example mount points:
/mnt/usb → USB drive
/media/user/disk → External hard drive
/dev/sda1 → A disk partition (not directly accessed, but mounted somewhere)

This differs from Windows, where each drive has its own root, like C:\, D:\, etc.

4. Key Differences Between Absolute and Relative Paths

Feature	Absolute	Relative
Starting Point	Root directory (`/` or `[drive]:\`)	Current working directory
Dependency	Independent of the current directory	Dependent on the current directory
Length	Typically longer	Typically shorter
Use case	Specifying the exact file locations	Navigating within a project or folder
Portability	Less portable across systems	More portable within a project.

Portability in the context of absolute and relative paths refers to how easily a file path can be used across different systems or environments. Absolute paths, which provide the complete location of a file starting from the root directory, are less portable because they often include specific drive letters or directory structures unique to a particular system. This means that if you move a project to another machine with a different file structure, the absolute paths may no longer be valid. On the other hand, relative paths, which are based on the current working directory, are generally more portable. They allow users to navigate and access files regardless of the underlying system because they rely on the structure relative to the current location, making them ideal for collaborative projects or when sharing code across different environments.

5. Practical Scenarios

Scenario 1: Accessing a Configuration File

Relative Path: ../config/settings.conf
This path assumes the current working directory is /etc/otherfolder and navigates up one level to access the settings.conf file.
Absolute Path: /etc/config/settings.conf
Absolute paths are preferred for settings and configurations because they provide a clear and unambiguous reference to file locations independent of the current working directory. This ensures that scripts or programs can consistently access configuration files from anywhere in the file system, reducing the risk of errors that can arise from incorrect relative paths. It also reduces duplication of the same configuration file in different directories.
The path is used to access the settings.conf file in the /etc/config directory, regardless of the current working directory.
Relative Path: ../config/settings.conf
However, relative paths might still be used in cases where portability is essential, such as in project-specific environments where files are organized in a consistent structure. For example, when developing applications with collaborative teams or when sharing project folders, relative paths simplify reference within the project's directory without needing to modify paths for different users or systems.
This path assumes the current working directory is /etc/otherfolder and navigates up one level to access the settings.conf file.

Scenario 2: Running a Script

Absolute Path: /home/user/scripts/start.sh
This path is used to run the start.sh script from anywhere in the file system.
Relative Path: ./scripts/start.sh
This path assumes the current working directory is /home/user and runs the start.sh script from the scripts subdirectory.