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Thursday, March 8, 2001TABLE OF CONTENTS
1) Sean’s Notes
2) Linux News
SuSE 7.1 - A First Look
The Little Engine that Could
Get 'yer BOFH Gear Here
IBM Puts on the Tux3) Linux Resources
Security Features in 2.4
More Uses of TCP Wrappers
The e-smith Server and Gateway: A Perl Study
BOFH Archive
UNIX System Administration Handbook4) App o’ the week
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1) Sean’s Notes
In operating systems like Windows NT, a lot of the action is hidden from you. Sure, you can get a list of processes from the Task Manager, even its memory usage and CPU time, but if you want some real details, you have to grab some extra utilities from places like sysinternals.com.
UNIX, on the other hand, will give you all the information you need and more.
A process is really an instance of a program. The editor I am typing this in is a process. It was started from the shell, which is another process. That shell was started… you get the point. Each process has a name, a priority, a number, and a whole whack of other attributes.
A process is identified by its process ID, or PID for short. Typing “ps -ef” will show you all the running processes. Here is one such entry from the list
UID PID PPID C STIME TTY TIME CMD root 874 805 0 Mar05 pts/1 00:00:00 ssh poochie
Starting from the left, you can see the owner of the process, namely root. The process id is next, which is 874. What’s PPID though? That’s the Parent Process ID, ie. the process that invoked this one. So what would that be?
% ps -ef | grep 805 sean 805 794 0 Mar05 pts/1 00:00:00 -csh
Hmm… owned by sean, with process id 805 and parent 794.
sean 794 1 0 Mar05 ? 00:00:04 gnome-terminal
And finally parent is process #1. Discussion of process 1 (init) will have to wait for another day, so let’s get back to the other fields. ‘C’ is the CPU usage value used for scheduling.
TTY is the terminal (a throwback to “Teletype”). Users interact with terminal devices. If you look at the process tree above, you’ll see that gnome-terminal has no TTY, but its child, -csh, does. Following that logic, you can see that I typed in “ssh poochie” to my shell in my gnome- terminal, to get process 874.
The second from last field is the CPU time the process has used. Remember that we’re in a multi-tasking operating system, so even though everything looks like it has the full attention of the CPU, it’s really taking turns with all the other processes. gnome-terminal has taken up 4 seconds of CPU time, and the other two haven’t yet taken up a second.
Of course, the last field is the name of the command. This is changeable, so you can’t rely on it 100%.
So, from the “ps -ef” listing, you can figure out a few things. Processes that have a TTY associated with them are talking via the keyboard with the user. If it is listed as ’?’, then it’s more than likely running in the background. Processes with a high CPU time may have busy loops, or other hangs. Older versions of syslogd would chew CPU, and thus, show up very clearly in a ps listing.
The date (STIME) of a process is also helpful. Daemons that start up per connection (anything run out of inetd, sendmail, httpd) that have children with old STIMES may be stuck. It’s unlikely that someone has been FTPing to your site for the past week!
My apologies to the readers that joined between February 22 and March 1. I had written a two part article last week, but the second part wouldn’t have made much sense without the first. I’ve archived it for you here:
http://www.ertw.com/~sean/newsletter/February+22%2C+2001
Thanks to the reader that pointed this out! As always, feel free to email me with your comments, or post questions on the various boards on Brainbuzz.com.
Long live the Penguin,
Sean mailto:swalberg@brainbuzz.com
Visit The Linux Newsletter Board http://boards.brainbuzz.com/boards/vbt.asp?b2
2) Linux News
SuSE 7.1 - A First Look
SuSE, a distribution from Germany, has become popular with a lot of people. This review shows what’s new and great in the latest version. It’s one of the first released distributions with the 2.4 kernel, BTW.
http://www.linux.com/newsitem.phtml?sid=1&aid830
The Little Engine that Could
With the decline in prices and the insane increase in speed, PCs have taken the digital effects world by storm. Come see how Linux is making inroads into this industry because of its ease of administration and increasingly available software.
http://www.millimeter.com/2001/02_feb/features/linux/engine.htm
Get ‘yer BOFH Gear Here
Show your users that you won’t take any flak from them by wearing some BOFH gear. Don’t know what BOFH is? Check out the “BOFH Archive” below. The phrase “What’s your username?” will never mean the same thing again!
http://www.theregister.co.uk/content/31/17033.html
IBM Puts on the Tux
I’m looking forward to seeing this one on TV… IBM is going for a 60’s style psychedelic ad featuring the Linux penguin. The rest of this article shows some impressive numbers– 144% growth in IBM Linux server sales in Asia during 2000, and a global growth of 24%, which beat Microsoft’s 20%.
http://www.wired.com/news/business/0,1367,42156,00.html
3) Linux Resources
Security Features in 2.4
Linuxsecurity.com has come out with another great article on new features in Linux 2.4. This time, Dave Wreski talks about “capabilities”, which are fine-grained permissions designed to reduce reliance on the root account. The second half of this article is about the cryptographic features available to plug in to the kernel, such as encrypted file systems.
http://www.linuxsecurity.com/feature_stories/kernel-24-security.htm l
More Uses of TCP Wrappers
TCP wrappers are great for controlling who can and can’t connect to your TCP-based services. Access control is just the beginning, though. This article takes an in-depth look at how the wrappers work, and explores a couple of extra goodies that you may not know the wrappers have in them.
http://www.freeos.com/articles/3729/
The e-smith Server and Gateway: A Perl Study
e-smith is a pretty cool distribution of Linux, which builds appliance-like boxes with a great web interface. The web interface itself is a great example of what Perl can do, and this article gets behind the scenes with some great design tips.
http://www.perl.com/pub/2001/02/esmith.html?wwwrrr_20010220.txt
BOFH Archive
Maybe you’re wondering what the BOFH is. Maybe you’ve heard about it but haven’t read the stories. Maybe you’re a BOFH looking for some pointers. Here is a site with links to all the BOFH info anyone could ever want.
http://members.iinet.net.au/~bofh/
UNIX System Administration Handbook
If you manage more than a few UNIX machines, with several users, then you want this book. It’s targeted towards Solaris, Linux, FreeBSD, and HP/UX, and contains essential information on keeping everything running in top shape. An all-in-one reference for the system administrator, you’ll be keeping this one close at hand to help solve your UNIX problems.
http://itresources.brainbuzz.com/tutorials/tutorial.asp?t=S1TU1195
4) App o’ the week
The Apache Toolbox takes care of downloading and compiling various modules into your web server. Download this 46K script, navigate the menus, and tell it to start compiling. Presto! It will download the modules you asked for, and build them into an Apache source tree. A simple “make install” in that directory later, and you’ve got a new web server.
http://www.apachetoolbox.com/
(C) 2001 BrainBuzz.com. All Rights Reserved.
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