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Monitoring processes

From: Unix for Mac OS X Users

Video: Monitoring processes

In the last movie we saw how we can use the ps command to be able to view a list of the Unix processes that are running. But the problem with it is that sometimes we don't just want a snapshot in a moment in time. We actually want to be able to watch the processes. We want to be able to monitor them as the CPU and memory usage goes up and down, whereas processes start and stop. So to do that we need something that's a little more interactive that will keep refreshing and showing us the state of things as they change. The tool for doing that is called top. So if you simply type top and hit Return, you will get a list of the top processes.

Monitoring processes

In the last movie we saw how we can use the ps command to be able to view a list of the Unix processes that are running. But the problem with it is that sometimes we don't just want a snapshot in a moment in time. We actually want to be able to watch the processes. We want to be able to monitor them as the CPU and memory usage goes up and down, whereas processes start and stop. So to do that we need something that's a little more interactive that will keep refreshing and showing us the state of things as they change. The tool for doing that is called top. So if you simply type top and hit Return, you will get a list of the top processes.

Now, top processes depends on what order you've sorted it in. By default, it's sorted by the Process ID. So the most recent processes are at the top. You will see above that that we actually have a list of some summary information, the CPU usage, the memory usage, that kind of thing that's going on, and then we get that information for each one of these as well. So we can see how much memory usage it's using up and how much of our RAM it's using up. Now perhaps the most important thing you need to know about top is that you can hit the Q key to get back out of it. So Q will exit out and take you back to your command line. So there are some options that we can pass in when we launch top. We can say top -n to specify the number of processes to show.

By default, it shows however big the window is. But we can say, all right, we only want to see the top 10. We can specify the sort order. There are some special keys that we used to say the sort order and I can show you those in the moment. For now let's just say CPU. We're going to sort it by CPU usage and we can set the refresh rate. We will use the -s for seconds. By default, it's set to 1 second refresh. Let's set it to 3. So every 3 seconds it will refresh and then we can also pass in a capital U for user showing filter by user. So we are going to see only the user that we specify, Kevin in this case.

So we will see the top 10 processes of Kevins, sorted by CPU, refreshing every 3 seconds. So there you go! Now, every 3 seconds it will re-update, but you can see the thing that's using the most CPU is Snapz Pro, which is the program I'm using to record this video. We have some interactive commands that we can issue as well, the most important of which is the question mark. That's the same thing as sort of help. It displays this Help screen. Notice here that it gives you sort orders. Right now, I have it sorted by CPU. That's what it's telling you here. The current state. We can pick a different thing, we can sort by time, we can sort by size.

That's the resident memory size, which refers to the RAM that it's using up, and we can sort by user and so on. The man pages will detail what each of these actually does for you. We can also change the delay just by using s followed by the delay. So let's try that. Hit any key to continue. Now, we are back here again. Let's change our delay back to 1. I will hit s and 1, hit Return, and now it updates every 1 second. If we want to see all the users, we type a capital U and then I can just hit Return and that will show me all users now, not just Kevin. But one thing that we can't do from here is change the In value, the number of processes that it's showing.

That's not available. But the o, s, and capital U options are all still available from here. Now, there are some differences between top and different Unix versions. This is the way it works on the Mac. The Mac is a little bit limited in the interactive options that you can type. Something like Linux the version of top actually has a lot more options and shortcuts that you can use from that interactive page. So check the man pages, check that help page, and it will help you out with all the different commands that you can use. Let's launch it one last time and I just want to show you if I go ahead and I launch Firefox, and we can see it pop up and we can see the memory that it takes up and so on, all right? You can see it up here and then we come back to Firefox and we quit out of it again.

You can see that it goes away. So this is a nice little tool. You can just leave it open and watch the processes come and go. In the next movie we will actually take a look at how we can stop these processes from running.

Show transcript

This video is part of

Image for Unix for Mac OS X Users
Unix for Mac OS X Users

82 video lessons · 25626 viewers

Kevin Skoglund
Author

 
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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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