11 unix osx_commands


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UNIX Commands

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11 unix osx_commands

  1. 1. Just imagine a little over 20 years ago we were barely able to drag a mouse across the screen, let aloneget around a desktop interface without typing in a few command lines. Fortunately, things have drasticallychanged, but the command line still provides a powerful way of interacting with your Mac.Unfortunately, most Mac users never dive into UNIX because of how intimidating it can seem at first. Butfamiliarizing yourself with it -- even a little bit -- is a great way to build up your coding arsenal. We roundedup some of the most utilized UNIX commands you should know so you can get started tinkering withTerminal.Because the Mac is based around a UNIX kernel, the commands you learn below can be used with Mac,UNIX, or Linux-based systems. Windows, however, uses different Microsoft DOS-based commands thatare not compatible with UNIX, and vice-versa.Let’s get started learning some UNIX commands.Open Terminal (located in /Application/Utilities). You will notice that soon after it opens, you get a promptsimilar to the one shown in the image above. This prompt will have the computer name, followed by acolon, a tilde, and the username of the logged in user, ended with a dollar sign ($). This prompt meansthat the Terminal is waiting for keyboard input.
  2. 2. 1. lsThis command is used to list the directories and files while browsing through the command line. Thiscommand is typed with a lower-case “L” and “S” followed by the enter key (to send the command).After typing the command, the Terminal screen will have all of the files and directories listed inside of theworking directory.There are two variations on this command that provides more functionality than just listing the files andfolders for a particular directory. These commands are:
  3. 3. ls -l - Gives a long listing of the files and directories in the current directory. In addition, this command willalso show the permissions, user the file/directory belongs to, and the creation date.
  4. 4. ls -a - Lists all of the files/directories (including hidden files) in the current directory. This command isuseful if you have a hidden file that you need to find, edit, or delete.
  5. 5. 2. cdNo, we’re not talking about those old compact discs that people used to listen to, we’re talking about“change directory.” This command does just that. Type this command followed by the name of a directorythat you wish to change to, and it’ll change to that directory.If you had a Music directory inside of the current folder you’re browsing, you could type:cd MusicThis would change to the music directory.Just like the ls command, there’s a few variations on the cd command:cd - Just typing the command without a directory name after it will take you back to your home directory.cd .. - Typing the command with two periods after it will take you one-level up in the hierarchy (this meansthe parent directory to the directory that you’re currently in). So, if you were in the Music directory and
  6. 6. wanted to move back up to the parent directory you just moved from, you could type this command. Thinkof this functionality as pressing the back button in a Finder window.3. pwdPwd stands for “print working directory.” The working directory is whatever folder you’re currently in,which typically is the receiver of an action (such as directory creation or deleting files inside of a certaindirectory). So, if you’re ever uncertain about which directory you’re in, just typed pwd and Terminal willspit back to you the directory location.
  7. 7. 4. mkdirThis command creates a new folder in the current working directory. So, if you’re in a folder calledDocuments and you wanted to create a subfolder called “Test”, you could type the following command tocreate that folder:mkdir TestThe folder will then be created. To view or enter the folder, you can use ls and cd.
  8. 8. 5. rmDeleting files and folders in UNIX can be a little scary, so use caution. UNIX doesn’t have a trash bin thatyour files go to when deleted. Once you invoke the delete command, the files or folders will be gone.Forever. We cannot stress this enough.To delete a file, you will use the rm command. This stands for “remove.” So, if you had the file “test.txt” inyour current working directory, you would type the following command to remove it:rm test.txtThe file would then be removed from the directory that you’re currently working in.Alternatively, you could use rm -i test.txt, which asks for a confirmation before removing the file.Deleting directories (folders) can be a bit trickier. The standard rm will not work on removing directories.To remove a directory called “Test,” use the following command:
  9. 9. rmdir TestHowever, this command will only work on directories that don’t have additional files and subdirectoriescontained in them. To remove a directory that has files in it, you’ll need to use the following command:rm -r TestThis will use what’s known as recursion to delete all of the files and folders contained in the directorybefore finally deleting the directory itself.6. mv / cpThese two commands are used to move and copy files.The first, mv is used to move files from onelocation to another. Let’s say that I had a file located in my user folder, but I wanted it moved to a foldercalled Documents. I would use the mv like this:
  10. 10. mv ~/test.txt ~/Documents/test.txtThis will move the file from the first location that you specified to the second location.Let’s say that instead of moving the file from the first location to the second location, you wanted to copyit. That’s easy enough. Just replace the mv command with the cp command, like this:cp ~/test.txt ~/Documents/test.txt7. whoHave you ever wanted to find out who is logged onto your Mac? Perhaps you have a multi-user system,or have SSH enabled; either way, you might need to know who is logged in. This simple Terminalcommand can tell you very easily. Simply head to the command line and type in who. In a blink of an eye,the system will return a list of all the users currently logged on and what date and time they logged in.Pretty nifty, huh?
  11. 11. 8. catCat is a simple way to view the contents of a file. The name is short for “concatenate and display files.”Let’s say you have a file called “test.txt” in your working directory. You think you can delete it, but you’renot sure what the contents of the file are. Without having to open a command line editorlike nano, emacs,vi, or vim, you can simply type in the following command followed by the file name:cat test.txtThis command will then output the file’s contents to the screen.9. sudoSometimes it may be necessary for you to run a command as an administrator. If you were to get an errorlike “Error: Insufficient privileges,” just type the sudo command before the command you were actuallytrying to type. This will in turn cause Terminal to ask you for your password to authenticate you as anadministrator.The sudo command is needed for things like chmod, MacPorts, and other administrative tasks.
  12. 12. 10. control + CControl + C is a way to tell a running command line-based program to quit and return you back to thecommand line prompt. So, if you were running a ping or other command line tool, just press Control + Cto get back control.11. clearWe saved the best and easiest for last. By now, you’ve no doubt tried many of the commands, but thiscan leave your Terminal command rather busy with text flowing here and there. If you want to get rid of allthe previous commands and outputs being displayed on the screen, simply enter clear followed by theenter key. This will wipe your Terminal screen clean, ready for you to type more commands.For Mac OS X or Mac apps/iPhone apps Contactify@macinfosoft.comVisit our website at : http://macinfosoft.comGo through our rich information of knowledge sharing resources in our corporate blog:http://macinfosoft.com/blogConnect us in Social Mediahttp://twitter.com/macinfosofthttp://facebook.com/macinfosofthttp://www.linkedin.com/companies/macinfosoft-incWe are also experts in designing logos, websites, brochures, flyers, keynotes, SEO, SMO, SMM, SEM &comprehensive development for Macs, iPhone/iPad & Web.