Manual pages (man, --help)

$ man — the manual

Every classic Unix command ships with a manual page. Type man followed by the command name and you get a small reference book on it: what it does, every flag, examples, related commands.

man ls

In a real terminal, man opens in a pager (space scrolls, q quits, /word searches). Here in the sandbox, it prints a one-line summary — enough to remember what each command does.

› try: man ls

$ --help — the short version

Most modern command-line programs respond to --help with a short usage summary. It's faster than reading a manual page when you just need a reminder.

grep --help

$ reading a synopsis

Manual pages start with a SYNOPSIS line that looks like a small grammar:

ls [-aAhl] [file ...]

The conventions:

• Things in [brackets] are optional.
• ... means "one or more."
• Flags written together like -aAhl can be combined or split.

Once you can read a SYNOPSIS, you can teach yourself any command without looking it up online.

$ when you're stuck

The order I reach for, in real life:

1. command --help — fastest, often enough.
2. man command — when you need the full picture.
3. Search the web — only after the first two come up short.

The programs themselves are the most authoritative source. Asking ls what it does is more reliable than asking the internet what ls does.