Absolute vs Relative Paths

Two ways to point at a file

An absolute path starts at the root: /Users/me/projects/foo.txt. It always means the same file no matter where you are. A relative path is interpreted from your current working directory: projects/foo.txt means "projects/foo.txt under wherever I am right now."

Special navigation tokens

• . — current directory
• .. — parent directory
• ~ — your home directory
• ~user — that user's home
• - (only with cd) — previous directory

Combine them: cd ../../sibling-project, cp ./local.txt ~/backups/.

When to use which

Scripts that run from cron or CI should use absolute paths — you don't know what their working directory will be. Day-to-day shell work uses relative paths because it's faster and reads naturally. The shebang line at the top of every script is always absolute: #!/usr/bin/env bash is interpreted by the kernel, which has no concept of "current directory."

Resolving paths programmatically

realpath foo.txt turns a relative path into an absolute one and resolves symlinks. readlink -f is similar (Linux). On macOS, realpath is in coreutils via Homebrew, or use the BSD trick cd "$(dirname foo.txt)" && pwd -P.