Start learning with our library of video tutorials taught by experts. Get started

Unix for Mac OS X Users
Illustration by

Who am I?


From:

Unix for Mac OS X Users

with Kevin Skoglund

Video: Who am I?

In this chapter, we're going to talk about file ownership and privileges. Let's begin by making sure we can answer the question "who am I?" In chapter 1, we talked about how Unix is fundamentally designed to be a multiuser environment, and we've talked about how we log in each time we open a Terminal window. Now in Unix, a user is someone who has an account on the system and each user on the system wants to keep their private files private and only share certain files with others. Otherwise, if everyone has access to everything all the time ,then what's the point of even having logins and user accounts? So fundamental aspect of this multiuser environment is that a user has total access to their own files, limited access to other people's files, and so that we can have collaboration, we have the ability to grant permission to certain files to certain people.
Expand all | Collapse all
  1. 3m 57s
    1. Introduction
      1m 14s
    2. Using the exercise files
      2m 43s
  2. 32m 2s
    1. What is Unix?
      7m 27s
    2. The terminal application
      4m 23s
    3. Logging in and using the command prompt
      5m 19s
    4. Command structure
      5m 22s
    5. Kernel and shells
      5m 25s
    6. Unix manual pages
      4m 6s
  3. 15m 58s
    1. The working directory
      2m 49s
    2. Listing files and directories
      3m 59s
    3. Moving around the filesystem
      4m 58s
    4. Filesystem organization
      4m 12s
  4. 1h 4m
    1. Naming files
      5m 41s
    2. Creating files
      2m 19s
    3. Unix text editors
      6m 39s
    4. Reading files
      5m 35s
    5. Reading portions of files
      3m 27s
    6. Creating directories
      2m 40s
    7. Moving and renaming files and directories
      8m 32s
    8. Copying files and directories
      3m 7s
    9. Deleting files and directories
      3m 38s
    10. Finder aliases in Unix
      4m 10s
    11. Hard links
      5m 30s
    12. Symbolic links
      6m 36s
    13. Searching for files and directories
      6m 32s
  5. 34m 58s
    1. Who am I?
      4m 3s
    2. Unix groups
      1m 52s
    3. File and directory ownership
      6m 41s
    4. File and directory permissions
      4m 27s
    5. Setting permissions using alpha notation
      6m 49s
    6. Setting permissions using octal notation
      3m 49s
    7. The root user
      1m 57s
    8. sudo and sudoers
      5m 20s
  6. 52m 34s
    1. Command basics
      4m 4s
    2. The PATH variable
      4m 13s
    3. System information commands
      3m 40s
    4. Disk information commands
      6m 8s
    5. Viewing processes
      5m 0s
    6. Monitoring processes
      3m 36s
    7. Stopping processes
      3m 19s
    8. Text file helpers
      6m 50s
    9. Utility programs
      7m 28s
    10. Using the command history
      8m 16s
  7. 20m 39s
    1. Standard input and standard output
      1m 24s
    2. Directing output to a file
      4m 13s
    3. Appending to a file
      2m 44s
    4. Directing input from a file
      5m 28s
    5. Piping output to input
      4m 40s
    6. Suppressing output
      2m 10s
  8. 41m 28s
    1. Profile, login, and resource files
      9m 11s
    2. Setting command aliases
      6m 59s
    3. Setting and exporting environment variables
      4m 54s
    4. Setting the PATH variable
      6m 10s
    5. Configuring history with variables
      6m 17s
    6. Customizing the command prompt
      6m 5s
    7. Logout file
      1m 52s
  9. 1h 25m
    1. grep: Searching for matching expressions
      5m 21s
    2. grep: Multiple files, other input
      4m 28s
    3. grep: Coloring matched text
      2m 57s
    4. Introduction to regular expressions
      3m 22s
    5. Regular expressions: Basic syntax
      3m 19s
    6. Using regular expressions with grep
      5m 20s
    7. tr: Translating characters
      8m 17s
    8. tr: Deleting and squeezing characters
      5m 30s
    9. sed: Stream editor
      7m 45s
    10. sed: Regular expressions and back-references
      7m 8s
    11. cut: Cutting select text portions
      7m 42s
    12. diff: Comparing files
      4m 35s
    13. diff: Alternative formats
      4m 30s
    14. xargs: Passing argument lists to commands
      7m 25s
    15. xargs: Usage examples
      7m 59s
  10. 42m 25s
    1. Finder integration
      4m 45s
    2. Clipboard integration
      5m 5s
    3. Screen capture
      3m 42s
    4. Shut down, reboot, and sleep
      3m 34s
    5. Text to speech
      2m 36s
    6. Spotlight integration: Searching metadata
      3m 41s
    7. Spotlight integration: Metadata attributes
      4m 24s
    8. Using AppleScript
      5m 23s
    9. System configurations: Viewing and setting
      5m 51s
    10. System configurations: Examples
      3m 24s
  11. 1m 26s
    1. Conclusion
      1m 26s

Watch this entire course now—plus get access to every course in the library. Each course includes high-quality videos taught by expert instructors.

Become a member
please wait ...
Unix for Mac OS X Users
6h 35m Beginner Apr 29, 2011

Viewers: in countries Watching now:

Unix for Mac OS X Users unlocks the powerful capabilities of Unix that underlie Mac OS X, teaching how to use command-line syntax to perform common tasks such as file management, data entry, and text manipulation. The course teaches Unix from the ground up, starting with the basics of the command line and graduating to powerful, advanced tools like grep, sed, and xargs. The course shows how to enter commands in Terminal to create, move, copy, and delete files and folders; change file ownership and permissions; view and stop command and application processes; find and edit data within files; and use command-line shortcuts to speed up workflow. Exercise files accompany the course.

Topics include:
  • Moving around the file system
  • Creating and reading files
  • Copying, moving, renaming, and deleting files and directories
  • Creating hard links and symbolic links
  • Understanding user identity, file ownership, and sudo
  • Setting file permissions with alpha and octal notation
  • Changing the PATH variable
  • Using the command history
  • Directing input and output
  • Configuring the Unix working environment
  • Searching and replacing using grep and regular expressions
  • Manipulating text with tr, sed, and cut
  • Integrating with the Finder, Spotlight, and AppleScript
Subjects:
Developer Web
Software:
Mac OS X Unix
Author:
Kevin Skoglund

Who am I?

In this chapter, we're going to talk about file ownership and privileges. Let's begin by making sure we can answer the question "who am I?" In chapter 1, we talked about how Unix is fundamentally designed to be a multiuser environment, and we've talked about how we log in each time we open a Terminal window. Now in Unix, a user is someone who has an account on the system and each user on the system wants to keep their private files private and only share certain files with others. Otherwise, if everyone has access to everything all the time ,then what's the point of even having logins and user accounts? So fundamental aspect of this multiuser environment is that a user has total access to their own files, limited access to other people's files, and so that we can have collaboration, we have the ability to grant permission to certain files to certain people.

Before we can do that though, we need to understand who we are and in Unix,= we can just simply type whoamI and it will tell you who you are. Now that may seem like a really sort of obvious answer because you're on your Mac. It's just you, you know you're logged in as you, but when you're working in Unix, it isn't always completely clear. You can actually switch users. We'll see how to do that little later. You may be logged into a remote Unix server like a web server. There are Web servers where I can log in as a specific user or I could login as root, and then it's important to know who am I right now.

If you can't do something that you think you ought to be able to do. If you can't open and read a file that you think you ought to have permission to read, well you can just type whoamI as a sort of sanity check to be like oh right, when I started this whole process, I logged in as a different user. I need to exit out and log back in as that other user or switch users so that then I have permission to do the thing that I want do. So it is an important concept in Unix. To keep most of the user's private files, each user gets a home directory. We saw that earlier. We used cd and then the twiddle or tilde as a shortcut and that's the shortcut to get to my home directory for kevin's home directory.

Whoever I'm logged in as that's where it's going to send me. Incidentally, that value is stored in home. So $home, that's where my home directory is. Each user has a different value when they logged in for home. For OS X those are located inside capital users and then the username. On a lot of other Unix systems, it will be home/ and then whatever the username is. So it will be something like that. So just to show you it's not there on the Mac, but that's where it'd live on the Unix systems. So now that we're clear on who we are right now, where we should be putting most of our private files, we are set up well to talk about the idea of file ownership and permission and how we go about changing those.

One thing that we touched on earlier that I want to make sure I mention again is that you can create other users. So you can go to your Apple menu > System Preferences and then from Accounts, you can click lock here to make changes and then click the plus sign and then you will be able to create new users. If you then want to switch and log out as a user, it'll quit all your programs and everything. So anything you have been working on will be gone, but what you'll do is from the Apple menu, you pick Log Out as that user. You don't have to shut down, you don't have to restart, you can just log out. Your Mac is still running. Unix is still running. You've just logged out as one user and it gives you the opportunity to log back in as a different user.

So you can try it out. You can create another user and you can try out a lot of the things that we're going to do here and you'll be able to see how the ownership and permissions affect things. Now you may not want to do that a lot because you are going to have to quit out of everything and then relaunch it all again, but it might be worth doing at some point during the exercises just to watch several of the movies in this chapter and then log out as one user, log back in as a different user, and see what you have the ability to do. Now some of you out there may be thinking "Well, I am the only user on my Mac and I'm always going to be the only user on my Mac and I am not going to work on any remote Unix servers or anything.

So I can skip all this. I don't need to know it." You can't. You really do need to still understand the idea of ownership and permissions because it's such a fundamental part of the way Unix works that you can't work in Unix without understanding how it works and how to manipulate them.

Find answers to the most frequently asked questions about Unix for Mac OS X Users.


Expand all | Collapse all
please wait ...
Q: The exercise files for the following movies appear to be broken:
07_02_files
07_03_files
07_04_files
07_05_files
08_03_files

Is there something wrong with them?
These exercises include one or more "dot files", whose file names start with a period. These files are normally hidden from view by the Finder.  So that they would show up in the Finder, the period has been removed from the file names. Additionally, "_example" has been added at the end of the file name to make it clear that the file will not work as-is. To make the dot files usable, either:

1) Open the file in a text editor to view its contents. Note that it may not be possible to double-click the file to open it because there is no file extension (such as .txt).
2) Resave the file under a new name (usually by choosing File > Save As), adding a "." to the beginning of the file name and removing "_example" from the end.

OR

1) Copy and rename the file from the Unix command line using the techniques discussed in this course. Rename the file by adding a "." to the start and removing "_example" from the end. Include the "-i" option to prevent overwriting an existing file unexpectedly.
Example:  cp -i ~/Desktop/Exercise\ Files/Chapter_07/07_02_files/bashrc_example ~/.bashrc
 
Share a link to this course

What are exercise files?

Exercise files are the same files the author uses in the course. Save time by downloading the author's files instead of setting up your own files, and learn by following along with the instructor.

Can I take this course without the exercise files?

Yes! If you decide you would like the exercise files later, you can upgrade to a premium account any time.

Become a member Download sample files See plans and pricing

Please wait... please wait ...
Upgrade to get access to exercise files.

Exercise files video

How to use exercise files.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.
Upgrade now


Exercise files

Exercise files video

How to use exercise files.

For additional information on downloading and using exercise files, watch our instructional video or read the instructions in the FAQ.

This course includes free exercise files, so you can practice while you watch the course. To access all the exercise files in our library, become a Premium Member.

join now Upgrade now

Are you sure you want to mark all the videos in this course as unwatched?

This will not affect your course history, your reports, or your certificates of completion for this course.


Mark all as unwatched Cancel

Congratulations

You have completed Unix for Mac OS X Users.

Return to your organization's learning portal to continue training, or close this page.


OK
Become a member to add this course to a playlist

Join today and get unlimited access to the entire library of video courses—and create as many playlists as you like.

Get started

Already a member?

Become a member to like this course.

Join today and get unlimited access to the entire library of video courses.

Get started

Already a member?

Exercise files

Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships. Learn more

Get started

Already a Premium member?

Exercise files video

How to use exercise files.

Ask a question

Thanks for contacting us.
You’ll hear from our Customer Service team within 24 hours.

Please enter the text shown below:

The classic layout automatically defaults to the latest Flash Player.

To choose a different player, hold the cursor over your name at the top right of any lynda.com page and choose Site preferencesfrom the dropdown menu.

Continue to classic layout Stay on new layout
Exercise files

Access exercise files from a button right under the course name.

Mark videos as unwatched

Remove icons showing you already watched videos if you want to start over.

Control your viewing experience

Make the video wide, narrow, full-screen, or pop the player out of the page into its own window.

Interactive transcripts

Click on text in the transcript to jump to that spot in the video. As the video plays, the relevant spot in the transcript will be highlighted.

Are you sure you want to delete this note?

No

Notes cannot be added for locked videos.

Thanks for signing up.

We’ll send you a confirmation email shortly.


Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

Keep up with news, tips, and latest courses with emails from lynda.com.

Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

   
submit Lightbox submit clicked
Terms and conditions of use

We've updated our terms and conditions (now called terms of service).Go
Review and accept our updated terms of service.