Common commands
Now that you know the basics of how paths work and how to interact with a terminal, we will present some common commands in more rapid succession. We will also list the commands we have already covered so you can use this as a quick reference.
If you want to know more about a command you can either use command --help to
print a quick reference, or use man <command> to get more thorough
documentation. The latter option can be a bit unintuitive to use at first, but
you can use the arrow keys to move up and down, and !kbd[q] to exit out of the
viewer. If you want to print out your own version of the below version you can
download a PDF here!
| Command | Description |
|---|---|
cat <files> | Print the contents of the <files> |
cd <path> | Changes your working directory to <path> |
cp <source> <destination> | Copies files from <source> to <destination> |
cp -r <source> <destination> | Copies directories and their contents from <source> to <destination> |
ls | Lists the files in the working directory |
ls <path> | Lists the files in <path> |
<command> --help | Print help for <command> |
man <command> | Prints the help page for <command> |
mkdir <directories> | Create the <directories> |
mv <source> <destination> | Moves files or directories from <source> to <destination> |
rm <files> | Removes the <files> |
rm -r <directories> | Removes the <directories> and all of their contents |
touch <files> | Creates the <files> |
More on notation
Sometimes when looking through the help page for commands you might see something like this:
touch [OPTION]... FILE...
Here the square brackets ([]) indicate optional arguments. Sometimes they
might list exactly which flags or arguments you can provide, but in this case it
just says options. You might also see required arguments in all caps without any
angle brackets (<>), such as in this case.
The ellipsis (...) also bear significance. They indicate that you can specify
multiple of the preceding item. So for this command we can provide multiple
options and multiple files.
System files
Sometimes when working in a terminal, you need to touch system files or run
commands that affect core parts of the system. When you do this, you will get an
error that says "Permission denied". In these cases, you need to give extra
permissions to the command by typing sudo followed by the command you want to
run. For example (don't run this):
sudo cp /etc/fstab /etc/fstab.copy
After pressing !kbd[Enter], depending on how your system is configured, you will be prompted for your users password. While typing it in, you will notice no characters are appearing on screen. Don't worry, your typing is being registered, this is just another security measure to make sure no one is peaking over your shoulder and sees the password. Once you have typed in your password, press !kbd[Enter] and if your password is correct, the command will be run with elevated privileges.
Mind you, you should actually be careful with
sudo. We've said earlier that it is difficult to do proper damage to your computer butsudois the one command that actively lets you do things to your computer that might be dangerous. It is used for many everyday things, so you might get used to using it. But if you get a warning telling you that you need sudo, don't just do it right away without thinking about its effects. If you're not sure what a command does you can always look it up online!
You can configure which users can use sudo and which commands they are allowed
to run with it in order to limit the access they get to your system. Commonly it
is setup so you can run any command with sudo, provided you can authenticate
yourself with your password.