Directory

Core Idea

A directory is a filesystem object that maps names to entries such as files, subdirectories, and special objects.

Commands To Try

pwd
ls -la
mkdir -p ~/playground/nested
rmdir ~/playground/nested
find ~/src -maxdepth 2 -type d

Directory Permissions

Read permission lets you list names. Write permission lets you add or remove entries. Execute permission lets you traverse into the directory. Directory execute permission is why x matters even when a directory is not a program.

Mental Model

Think of a directory as a table of names. The table itself has permissions and metadata. Entries inside it also have their own permissions and metadata.

Common Confusions

• rmdir only removes empty directories.
• rm -r removes a directory tree and is dangerous outside scratch areas.
• A directory can be visible but not enterable if execute permission is missing.
• . and .. are directory references, not ordinary project files.

Proof Check

Run ls -ld ~ ~/src ~/src/pages and compare directory permissions.

Docs Pointers

• Run man mkdir, man rmdir, man find, and man chmod.
• Read Path, Filesystem, and Permissions.