Directories and Path Resolution

Suppose a backend service tries to open:

The storage device does not contain a built-in object with that full name. The operating system must interpret the pathname one component at a time:

At each step, the current object must be a directory, the process must be allowed to search it, and the next name must identify an entry. Symbolic links and mount points can redirect the walk before the final object is reached.

This process is path resolution.

A pathname is a route through a hierarchy of directories, not a permanent identity stored inside a file.

Understanding the walk explains absolute and relative paths, current working directories, . and .., “not found” errors, symbolic-link surprises, and a large class of security bugs.

This chapter develops the component-by-component path-resolution algorithm, covering absolute and relative roots, directory permissions, symbolic links, mount points, namespace changes, stable handles, directory-relative operations, and security.