On Unix/Linux command lines, which command is typically used to list the contents of directories (filenames, optionally with details)?

Introduction / Context:
Listing files is one of the most common terminal tasks. On Unix-like systems, the standard tool for enumerating directory contents is distinct from the commands used on DOS/Windows, so it is important for cross-platform users to recognize the correct utility and common flags.

Given Data / Assumptions:

• We are on a Unix/Linux shell.
• We want to see directory contents, optionally with long format, hidden files, or sorting.
• Coreutils are installed.

Concept / Approach:

The ls command lists files and directories. Common options include -l (long format), -a (include hidden files), and -t (sort by modification time). While some systems alias dir to ls, ls is the canonical Unix command.

Step-by-Step Solution:

Verification / Alternative check:

Use type ls or which ls to confirm the binary. Explore man ls for exhaustive options.

Why Other Options Are Wrong:

• tar: archiving tool, not directory listing (though it can list archive contents).
• dir: DOS command; on Unix it may be an alias but ls is standard.
• lp: print submission in System V printing.
• None: incorrect because ls is correct.

Common Pitfalls:

• Forgetting that globs expand before ls runs, affecting results.
• Confusing hidden file handling; add -a to include dotfiles.

Final Answer:

ls.