Terminal

A terminal is a program that allows you to type commands for your computer to execute and view the results as text. You can run other programs from a terminal, and it can serve the same role as many other programs you're used to using.

Terminal Programs

On Unix-like operating systems (such as Mac and Linux), you should be able to find the default terminal program by searching your applications for "terminal". This terminal is similar to what you'll see used in the videos. Many of these terminals run a program called bash or zsh underneath, and they should all accept the commands you see in the videos and other examples, so Mac and Linux users don't need to set up any additional terminal software.

On Windows, there are two built-in terminal programs, neither of which I recommend using:

• cmd is the classic Windows Command Prompt. Most commands that work with bash/zsh will not work in the command prompt.
• Powershell is a more advanced terminal for Windows that supports some of the commands you'll see used in bash terminals. However, it will likely not be able to run the test scripts you receive with your assignments and may not work with all of the commands you see us use.

There are several popular terminal emulators for Windows that emulate bash and allow you to run the same commands as a bash terminal. A good example is git bash, which is part of the Git for Windows project. If you are using Windows, you should install Git for Windows or another terminal emulator. This will allow you to run the test scripts for assignments and use the terminal commands you see demonstrated in class. It also includes the program git, which is used in some later CSC/SER classes.

Terminal Videos

Mark Lewis, the author of a textbook previously used for this class, has a playlist of videos covering how to use a terminal on YouTube. Watch these videos for a brief demonstration of the different terminal commands, and refer to the cheatsheet below if you would like a summary of useful commands.

Terminal Cheatsheet

Important terms/concepts:

• A directory is a folder on your computer.
• A path is the location of a file or directory. It is a series of directory names separated by forward slashes on Unix-like systems or backslashes on Windows. Examples:
  • /home/zach/Documents/Syllabus.pdf is the location of a file named "Syllabus.pdf". It is in a folder named "Documents", which is in a folder named "zach", which is in a folder named "home", which is at the root of the filesystem (indicated by the leading "/").
  • C:\Users\Zach\Documents\Syllabus.pdf is the equivalent path on Windows.
• A relative path only tells you how to get to a file or directory from your current location. For example, if we were in the folder /home/zach, then the relative path to "Syllabus.pdf" in the previous example would be Documents/Syllabus.pdf or ./Documents/Syllabus.pdf. A ./ at the start of a path refers to your current location, so a path beginning with ./ is always relative.
• Many commands will include placeholder text written in all caps. That part is not meant to be copied literally when you run the command. For example, you would type cd Documents to move to the "Documents" folder rather than literally typing cd PATH.
• Some commands have flags or optional arguments, which are normally written as one or two hyphens followed by a word or letter. These allow you to enable certain settings when running a command or include additional optional information. Some examples are the -a in ls -a or the --version in java --version.

Navigation:

• pwd: "print working directory", tells you which folder you're in
• cd PATH: "change directory", moves you from your current location to the directory at PATH
  • cd on its own or cd ~ will move you to your home directory
• ls: "list", lists everything in the current directory
  • ls PATH: lists the contents of the directory at PATH
  • ls -a: includes hidden items in the output

Viewing Files:

• cat PATH: show the contents of the file at PATH
• less PATH: view the contents of the file at PATH, but with more features. Press q to exit less and return to the terminal's command prompt.

Manipulating Directories:

• mkdir PATH: creates an empty directory at PATH
• rmdir PATH: deletes the directory at PATH, but only if it is empty

Manipulating Files (these are dangerous and can permanently delete files, so use with care!):

• rm PATH: delete the file at PATH. It's permanently gone, not moved to the trash or recycle bin.
• mv PATH DESTINATION: move the file or directory at PATH to DESTINATION. This can also be used to rename a file or directory. If you move a file to another file with the same name, you will replace the file that was already there, permanently deleting the old file.