How do you get quick help for a command without using man pages?

The fastest help is command --help, which prints a quick usage summary right in the terminal — no pager, no leaving what you're doing.

--help is the in-between option: more detail than tldr, far quicker than reading a full man page. Most programs support it and dump their usage and common options straight to the screen:

ls --help      # usage + the common options, inline
some_cmd -h    # some programs use the short -h instead

There's a subtlety, though: --help is a convention, not a guarantee. Each program implements it itself, so a few don't have it, and the shell's own built-in commands (cd, export, alias) aren't separate programs at all — they have no --help. For those you ask bash directly:

help cd        # built-in help for shell built-ins

This is exactly why type is so handy — it tells you what kind of thing a name is, so you know which help to use:

$ type cd       # cd is a shell builtin   → use:  help cd
$ type grep     # grep is /usr/bin/grep   → use:  grep --help  or  man grep
$ type ls       # ls is aliased to 'ls --color=auto'

Decision tree:

1. Know the command, want a quick reminder? → command --help
2. type says it's a built-in? → help command
3. Need the exhaustive detail? → man command
4. Don't even know the command name? → apropos keyword