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A Quick Guide to Using Command Line (Last)

Being able to employ command line is necessary for high-level coding. Here are the essentials you need to know.

Opening Command Line. If you've only started coding, you may take no thought what command line even is. No worries! It's just a simple way to tell your computer what to do. There are varying ways of accessing control line, depending on what operating system you use.

MacOS: Open spotlight search (default way to practice this is past hitting control and the space bar) and blazon in "terminal". Select the application chosen concluding and printing the render cardinal. This should open up an app with a black background. When y'all see your username followed by a dollar sign, you're ready to start using command line.
Linux: You can open Terminal past direct pressing [ctrl+alt+T] or you tin can search it up past clicking the "Dash" icon, typing in "concluding" in the search box, and opening the Terminal application. Once again, this should open up an app with a blackness groundwork. When you see your username followed by a dollar sign, y'all're set up to outset using command line.
Windows: On Windows 10, open the start menu and become to the shortcuts binder called "Windows System". Pressing the dropdown menu should reveal a shortcut to open the Command Prompt application. Right click on the shortcut, press "More", and press "Run every bit Administrator". For Windows viii, go to the start screen, press "All Apps", and scroll correct until the "Windows System" binder shows upwardly. Y'all can find Command Prompt there. For Windows 7, open the start menu and click on "All Programs". Click on "Accessories" and you'll find the Command Prompt shortcut. Right click on the shortcut and press "Run as Administrator".

Accessing Servers. If y'all run code on a server (e.g. a GPU cluster or something similar Amazon Web Services), you need to be able to access the server. The best method to do this through Secure Shell (ssh), which lets yous deeply control and modify your server using the Cyberspace. You lot can do this past typing in the following:

ssh username@host_server

Where username is the business relationship name of your account on the server, and host_server is the host (e.g. GPU cluster'south proper noun). If yous have a password to access your account on the server, control line will prompt y'all to enter that in. If information technology's your get-go time accessing that particular server, your estimator may also ask you if it can remember the authenticity primal — type in 'aye' or the corresponding phrase so that your computer doesn't enquire you this every fourth dimension. When you're linked up to the server, you should see that the control line starts with a green header with some kind of username@host format. Employ this as an indicator that you're really continued to the server.

Moving files. This one'southward pretty simple. Type in the following:

mv target destination

Where mv is move, target is the file you want to move, and destination is where you want to motion it to.

Copying files/folders. If you're trying to re-create files effectually, the easiest way to do this is using the cp command. Use the following script to copy around files.

cp -r target destination

In this script, cp represents copying and -r represents doing it recursively. The target is the target binder/file y'all're trying to re-create, and destination is the target binder yous're trying to re-create it to. Important notes:

Let's say you lot type in "cp -r dwelling/target/ habitation/destination/". If "home" is a binder and "target" is a folder, but "destination" is not a binder in domicile, so "target" will exist copied into habitation just volition exist named "destination".
Let's say y'all type in "cp -r home/target/ dwelling/destination/". If all of these are valid binder, "target" volition be copied every bit a folder inside of "destination" inside of "home" — you'll terminate up with a folder that's "home/destination/target/".
Permit'due south say y'all type in "cp -r home/target/ users/". This volition just re-create the "target" binder into the "users" folder under the same name (target).
Use the * character to correspond all. For example, to copy all files in a folder that start with the letter a, your target should exist "/folder/a*". To copy all files of a sure extension (say something similar .png), your target should exist "/folder/*.png".
Use the . graphic symbol to represent the current folder.
If the file/folder already exists in destination, it WILL Be OVERRIDDEN. So brand sure y'all don't make this rookie fault.

Deleting files/folders. Deleting files is pretty essential, and so here'south how you should do information technology. Use this script:

rm -r target

Where the rm represents remove and -r represents recursively doing it. Target is the file/folder y'all're trying to delete. More than pro tips if you didn't read the notes under "Copying files/folders":

This command will not allow you delete a file that's non there to brainstorm with (it'll say something like "no such file or directory)
Use the * character to represent all. For example, to delete all files in a folder that start with the letter a, your target should be "/folder/a*". To delete all files of a certain extension (say something like .png), your target should be "/folder/*.png".
Use the . character to represent the current folder.
This command will delete files VERY Quickly. When a file is deleted, yous can't go information technology back. There's no control-Z on this. Always make sure you type in the right directory/file.
Alternatively, you tin can enter "-i" later -r (e.g. rm -r -i target), which volition prompt the computer to ask for permission to delete every unmarried file.

Listing files. When you're in a folder, it's probably pretty useful to be able to see the files/folders in at that place. Use this:

ls target (options)

Target is the binder whose contents you're trying to list (if you're trying to listing the contents of the folder you lot're currently in, leave target blank). You lot tin too utilize the following options:

"-F": adds a grapheme for the blazon of file (e.g. a "*" for an exectuable script or a "/" for a directory).
"-f": stops the calculator from sorting the contents. Useful when there are huge numbers of files and it's not useful to sort the files.
"-a": lists all files, including hidden files that would normally be hidden.
"-h": volition permit you lot as well get the sizes of the files.
"-t": sorts the files by when it was last modified.

Changing the directory you're in. Use this simple command to change your current directory:

cd target

Where cd is change directory and target is the folder y'all desire to enter. More tips:

Use the . character to represent the current binder. Doing "cd ." will refresh what the control line says your current directory is (useful if you've changed a binder proper name in the path to your folder).
Use "../" to represent the enclosing folder. For example, if you're currently in "home/target/", then you can do "cd ../" to get to the "home" folder. The "../" is also stackable, so 2 of them would get you 2 folders back.

Making a new folder. This is likewise a pretty uncomplicated command. Utilise the following script:

mkdir target

Where mkdir is make directory and target is the name of the folder y'all want to make. For example, "mkdir target" would brand a folder called "target" inside of the directory command line is currently in.

Clearing out the clutter. When yous run likewise many commands, information technology's easy to get your command line screen cluttered upwardly with a bunch of green, blue, and white lines. Use this one word control to clear it up:

clear

Self-explanatory: clear represents clearing the screen.

Running scripts. If you're coding, you'll probable want to exist able to run your code using command line. Lucky for you, there's a great way to do this! Now, I'm a Python user, so here's Python kickoff:

python target

Target is the file you want to execute (information technology should end in ".py").

For Java, utilize this:

java target

javac target

Doing "java" will run the file, and "javac" will compile it. Target is the file you want to execute (it should end in ".coffee").

Other languages like C and JavaScript require special packages to run in command line, which I've hyperlinked instructions for.

Congratulations! Y'all're now capable of using command line (to a certain extent). These are just the basic commands, at that place are more specialized commands to use for specific tasks, but these are the ones that almost anyone using control line should know.