Command-Line
Tools
COP-3402

You can create an ssh key and add it to eustis's .ssh/authorized_keys to login without a password.

# if you haven't already generated a key, run ssh-keygen
ssh-keygen
# accept the default location (as long as you haven't already generated


# now let's tell eustis about your public key (be sure to use .pub!)

# linux/mac
cat ~/.ssh/id_rsa.pub | ssh NID@eustis.cecs.ucf.edu 'cat >> .ssh/authorized_keys'

# windows (https://superuser.com/questions/1747549/alternative-to-ssh-copy-id-on-windows)
type %USERPROFILE%\.ssh\id_rsa.pub | ssh NID@eustis.cecs.ucf.edu "cat >> .ssh/authorized_keys"

# windows alternative (rsa_id.pub instad of id_rsa.pub)
type %USERPROFILE%\.ssh\rsa_id.pub | ssh NID@eustis.cecs.ucf.edu "cat >> .ssh/authorized_keys"

This is the bash shell program running and waiting for you to type commands.

bash will only run programs found in directories listed in the $PATH environment variable or when given a path to the program.

This is why you need to type ./ before C programs after you compile them, e.g., ./a.out, because you are giving a path to a program to bash.

To quickly clear your screen, and put the prompt at the top of the screen, use Ctrl-L (or type the clear command).

Let's look at an example hierarchy and see how bash commands move us around the file system.

bash (and every process) are associated with a current working directory, which affects how we reference the locations of files; any relative paths will start from the current working directory. Relative paths are any paths not starting with the root of the file system /.

A string that contains the sequence of directory names along the file tree to the directory that contains the file and the file name itself. Allows you to uniquely identify files, even those with the same name.

./hello cd ..

Where is the "." and ".." in our file tree?

In order to answer this, we need to introduce a new concept, the working directory.

Arguments are separate by spaces.

What if the argument has a space in it?

• escape the space with a backslash ~\ ~
• Use double-quotes (evaluates the contents, e.g., for bash variables and escape sequences)
• Use single-quotes (does not evaluate contents or escape sequences)

What kind of path is this, relative or absolute?

Use eustis's /usr/include as an example file hierarchy

These are where system-wide C header files are installed

What is the .. directory?

Where are we now? How do we find out?

Get used to running pwd and ls to orient yourself

What kind of path is this, relative or absolute?

What if we had done cd ./include instead? What's the difference? Why do we have the . folder?

One of these most useful features for speed on the command-line

Works for files and directories, command-line arguments, and commands themselves.

You can even create completions for your own software.

https://www.gnu.org/software/bash/manual/bash.html#Commands-For-Moving

bash has emacs-like commands.

https://www.gnu.org/software/bash/manual/bash.html#Commands-For-History

keypression-mode

Warning: avoid opening multiple instances of the editor on the same file, or you may accidentally overwrite unsaved changes.

Note: eustis is configured to prohibit background processes from running after quitting and will kill them.

You can ask rm to remove non-empty directories and their contents recursively, but it's a bit dangerous.