Ryan Greenberg

If you type help in most shells what you get is not very helpful:

$ help
zsh: command not found: help

bash is slightly better; fish is actually good.

Eventually you learn that help is obtained from the manual by running man. After you chuckle at the combinations this permits—man less, man cat, man man, man date—you confront a second reality which is that the manual can be overwhelming to the point of not being helpful.

$ man ls

NAME
     ls – list directory contents

SYNOPSIS
     ls [-@ABCFGHILOPRSTUWabcdefghiklmnopqrstuvwxy1%,] [--color=when] [-D format] [file ...]

[...]

Enter tldr pages, “collaborative cheatsheets for console commands,” which provide a few examples of common usage. Here’s the page for ls:

$ tldr ls

ls

List directory contents.
More information: <https://www.gnu.org/software/coreutils/manual/html_node/ls-invocation.html>.

- List files one per line:
    ls -1

- List all files, including hidden files:
    ls [-a|--all]

- List files with a trailing symbol to indicate file type (directory/, symbolic_link@, executable*, ...):
    ls [-F|--classify]

- List all files in [l]ong format (permissions, ownership, size, and modification date):
    ls [-la|-l --all]

- List files in [l]ong format with size displayed using human-readable units (KiB, MiB, GiB):
    ls [-lh|-l --human-readable]

- List files in [l]ong format, sorted by [S]ize (descending) recursively:
    ls [-lSR|-lS --recursive]

[...]

You can install tldr with your package manager (e.g. brew install tldr) or read at https://tldr.inbrowser.app. It’s easy to contribute new commands and examples; I always forget how to use units so I added examples to tldr.