Engineering Craft › Developer Tooling

Getting Help (man, --help, tldr)

Reading a command's built-in documentation.

Also known as: man, --help, tldr, manual pages

Command-line tools come with built-in documentation. Learning to read it means you can answer “what does this flag do?” in seconds, without leaving the terminal.

The three levels

ls --help            # a short summary of options (works for most tools)
man ls               # the full manual page
tldr ls              # community-written, example-first cheat sheet (install it separately)

man opens a pager. Use these keys:

How a man page is organized

• NAME: one-line description.
• SYNOPSIS: the command’s shape. Square brackets [ ] mean optional, | means “or”, and ... means repeatable.
• DESCRIPTION and OPTIONS: every flag.
• EXAMPLES, SEE ALSO, and sometimes EXIT STATUS.

SYNOPSIS
       grep [OPTION...] PATTERNS [FILE...]

Finding things

man -k "copy files"     # search manual descriptions (same as apropos)
which python            # where a command lives
type cd                 # is it a built-in, an alias or a program?

Tips

• Start with --help or tldr for quick examples, and man when you need the details.
• Flags differ between systems (GNU/Linux vs macOS). If an option isn’t accepted, check the local man page, not an online answer for another system.
• Shell built-ins like cd are documented in the shell’s own manual (help cd in bash).
• Tools without man pages often have tool help or online docs (reading docs).