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Unix for Mac OS X Users
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System information commands


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Unix for Mac OS X Users

with Kevin Skoglund

Video: System information commands

In this chapter, we are going to be looking at useful commands that we can use in Unix, and I want to start us off by looking at useful system information commands. The first one we'll look at it is probably the simplest, which is just simply date and that tells you the current date. That's a nice handy thing. If you want to know what the current date is, you just type date and it tells you. Keep in mind that this value is the date that the computer has been set to, which is not necessarily correct. Hopefully, we did set our Mac up to have the correct date, but it's essentially the same date that you would see up here on your Mac if you had a clock display. You would set this value via the system preferences and the date and time settings.
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  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

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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

System information commands

In this chapter, we are going to be looking at useful commands that we can use in Unix, and I want to start us off by looking at useful system information commands. The first one we'll look at it is probably the simplest, which is just simply date and that tells you the current date. That's a nice handy thing. If you want to know what the current date is, you just type date and it tells you. Keep in mind that this value is the date that the computer has been set to, which is not necessarily correct. Hopefully, we did set our Mac up to have the correct date, but it's essentially the same date that you would see up here on your Mac if you had a clock display. You would set this value via the system preferences and the date and time settings.

So that's what it's telling you. This is the date the system thinks it is. We also have uptime. That's going to report to us the time that it's been turned on. You can see that I've been up for three hours. So for three hours I've had Unix up and running. That's the time since I booted my computer. It tells you also the time here. Don't need to worry about the load averages here. That's letting you know just sort of how well the system is performing. You won't need to worry about that. Notice that it says 2 users. You may be thinking, well, wait a minute! 2 users? Why are there two users? Well, we can actually use a couple of other commands.

Let's use users and that shows you just one user. So wait a minute, so that doesn't seem to match. Or who. who shows us a list of all users and what they're doing and it doesn't de-dupe it. users de-duped the 2. There is actually two Kevins logged in. One of them is the Terminal program that I am using now when I open up a new bash shell. But keep in mind that I also have the Finder running here, which is also interfacing with Unix. So it has to be logged in as Kevin as well. So those are the two users, the one that's sort of outside here in the Finder and the one that's inside this window.

I am going to actually open up a new Terminal window and then from here you will see now we have a second one. We can type who. You can see now we have three. There is ttys000, which is this other one over here and the other one has been called ttys001. So that's how it keeps them straight. So who shows you each of these occurrences every time that I log in, whereas if you just type users, it just shows you the one user, Kevin. It doesn't care the fact that there are several of them. So those are useful commands. uptime, users, and who. We also have uname, which returns the operating system name.

Now, you may be like "Wait a minute! Darwin? I thought I was using Mac OS X." Remember when we talked about back, when we said what is Unix? Darwin is the name that Apple gives to their version of Unix with all the extra code that they've added in on top of it. All the proprietary stuff as well as the open-source stuff altogether is called Darwin. So that is the version of Unix that we are running. OS X is running on top of that. We are talking about the Unix name. That's the u in front of it. uname is Darwin. We also can pass in some options here. uname, dash, and the options are mnrsv and p and that will return all sorts of information to us, not just the operating system but you can see it tells me 10.6 is what I am running.

It gives me real specific information about the release that I'm running. It tells me my processor, the hardware that I'm running on, and actually a shortcut for all of those. For everything except the P is the A option. That does mnrs and v altogether. P is the processor, and that's the second. You can see that those are actually the same, the last two entries there but that will do the same thing for you. You can check the man pages to see what all those are but that just gives you a little more information about the system that it's running on. We also can use hostname and domainname. Those are more useful when you're in a networked environment.

The hostname would be the host that we are on and domainname for me is not set to anything but on a web server or some kind of a shared Unix work server, those might return something more useful to you. So together those commands make up some tools that we have to find out some basic system information.

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


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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
 
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