Getting help on the command-line
You may already be familiar with some basic ways to get help in the shell, e.g.:
help: Show list of shell commandswhatis: Display one-line manual page descriptionsapropos: Search the command manual page names and descriptionsman: View system reference manuals for individual commandsman ls: View manual forlscommandman hier: Description of the *nix filesystem hierarchy
When encountering a new command, it is a good habit to quickly check what it does using whatis or man before using it. This can help avoid any unintended side effects that can occur when copy-pasting commands to the terminal (which is not recommended).
Interactive system documentation
Apart from the above, there are also other ways to get help while using the command-line.
First, there is a comprehensive and interactive guide to the Unix Shell and GNU CoreUtils that is accessible by simply typing info.
Within info, you can move around with the arrow keys on your keyboard and select underlined chapters (nodes) using the Enter/Return key. You can go back to the previous node with p or read the next node in the guide by pressing n. To return to the previous level up in the hierarchy of nodes, press u. To quit info just press q.
Help from the community
You can also get community-sourced help using a service like Cheat.sh. This works well with the curl command, which fetches online information and prints it to standard output.
To see examples of how to use the tar command, for instance, you just need to point curl to cheat.sh/ and add tar at the end of the URL. This also works to get help on specific topics in many programming languages (like Python) – just use an extra slash before the topic:
curl cheat.sh/tar # examples of using the tar command
curl cheat.sh/python/split # information about the split method in Python
curl cheat.sh # usage info