Archive for category Linux

More ‘tops’ to Keep you on Top

Yesterday, I posted about how htop was my new replacement for top on all Linux systems I manage. Tonight, while looking through the Google search words that lead people to my site, I found a Google result page which contained a 'hit' that immediately caught my eye. Mike Malone, of the I'm Mike blog had an entry titled 'Top 5 tops: keep tabs on your system'. In it, he describes not only the htop utility I came across earlier, but 4 additional tops to make any Linux administrator smile.

  1. mtop (MySQL top) monitors a MySQL server showing the queries which are taking the most amount of time to complete. Features include 'zooming' in on a process to show the complete query, 'explaining' the query optimizer information for a query and 'killing' queries. In addition, server performance statistics, configuration information, and tuning tips are provided.
  2. Apachetop is a curses-based top-like display for Apache information, including requests per second, bytes per second, most popular URLs, etc.
  3. iftop does for network usage what top does for CPU usage. It listens to network traffic on a named interface and displays a table of current bandwidth usage by pairs of hosts. Handy for answering the question "why is our ADSL link so slow?".
  4. htop, an interactive process viewer for Linux
  5. atop is a performance monitor that can display:
    • Resource consumption by all processes
    • Utilization of all relevant resources
    • Permanent logging of resource utilization
    • Highlight critical resources
    • Watch activity only
    • Watch deviations only
    • Accumulated process activity per user
    • Accumulated process activity per program
    • Disk and network activity per process

While I use mtop on a regular basis, and have now started using htop, the other 3 monitors definitely look like they're going to be part of my 'tools' for the various servers I manage. iftop and apachetop seem especially interesting to me, given their more specialized monitoring target.

I'm Mike | Top 5 tops: keep tabs on your system –

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htop – Unix top on steroids

A coworker of mine showed me a small utility he read about on LifeHacker (Manage Processes with htop) this morning. I checked out the htop project site and quickly downloaded the source rpm and built the package and installed it on one of my Fedora boxes at home.

Here’s how htop compares to top, taken straight from the htop project site:

Comparison between htop and top

  • In ‘htop’ you can scroll the list vertically and horizontally to see all processes and complete command lines.
  • In ‘top’ you are subject to a delay for each unassigned key you press (especially annoying when multi-key escape sequences are triggered by accident).
  • ‘htop’ starts faster (‘top’ seems to collect data for a while before displaying anything).
  • In ‘htop’ you don’t need to type the process number to kill a process, in ‘top’ you do.
  • In ‘htop’ you don’t need to type the process number or the priority value to renice a process, in ‘top’ you do.
  • ‘htop’ supports mouse operation, ‘top’ doesn’t
  • ‘top’ is older, hence, more used and tested.

All I can say is I’ll probably not use ‘top’ anymore. It’s htop for me going forward…

htop – an interactive process viewer for Linux –

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MySQL Monitor – Ajaxified

MySQL LogoI use a MySQL database in most, if not all, my website development projects. In some cases, especially with applications/sites that tend to get a large number of hits (and as such, a greater number of interactions with the database), it’s nice to be able to see what the DB engine is doing, how many threads are running, etc. My tool of choice has been MyTop by Jeremy Zawodny for a couple years now. Recently, it looks like someone wanting to learn some Ajax has decided to port Jeremy’s great tool over to an ajaxified webpage! No need to login to the database server and run mytop in a console anymore; now I can do it straight from a web browser!

The project is called ajaxMyTop and is hosted on Sourceforge. Currently, there is no home page or details on the project website, but Ajaxian has a good review of the application.

One note of caution; the application is written for PHP5. There is a small modification available which will enable the application to run under PHP4. It’s located in the ajaxMyTop forums:

Sites mentioned: – Ajaxian Review of ajaxMyTop – Jeremy Zawodny’s original mytop webpage – ajaxMyTop Project Website

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Rollback your RPM Installs on Fedora using Yum

There’s a little-known option in RPM that enables the rollback of package installs. Think of it like an undo option in your favorite application; it will rollback the package install to a previously known state/version. Yum support this option in Fedora Core 4 (and upcoming Core 5); here’s an excerpt taken from Chris Tyler’s posting on OreillyNet:

Here are cut-to-the-chase directions on using this feature:

  1. To configure yum to save rollback information, add the line tsflags=repackage to /etc/yum.conf.
  2. To configure command-line rpm to do the same thing, add the line %_repackage_all_erasures 1 to /etc/rpm/macros.
  3. Install, erase, and update packages to your heart’s content, using pup, pirut, yumex, yum, rpm, and the yum automatic update service.

If/when you want to rollback to a previous state, perform an rpm update with the --rollback option followed by a date/time specification. Some examples: rpm -Uhv --rollback '9:00 am', rpm -Uhv --rollback '4 hours ago', rpm -Uhv --rollback 'december 25'.

As Chris mentions, keep in mind that you’ll be using lots more storage space to keep prior versions of packages around.

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Good Review of the Upcoming Fedora Core 5

Fedora LogoAs many of my close friends know, I’m big into Fedora’s Linux distribution. It’s my distro of choice and I religiously update my ‘Cores’ as the lastest one comes out. I’ve been looking forward to the new Fedora Core 5 release and was interested in reading a good review, since I still have not had a chance to install it on a spare box. This review is both comprehensive and very well written:

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The Xen Virtual Machine Monitor

The Xen Virtual Machine MonitorIf you’re familiar with what VMWare does (the creation of smaller virtual machines running concurrently on the same computer), then you’ll want to take a serious look at the latest release of the Xen Virtual Machine Monitor. What exactly is Xen, you ask?

Xen is a virtual machine monitor (VMM) for x86-compatible computers. Xen can securely execute multiple virtual machines, each running its own OS, on a single physical system with close-to-native performance.

If you have a few minutes, check out the project’s website and give Xen a try whenever you need to setup any sort of Virtual Machine, either for testing purposes or for some debugging.

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Promising New Webmail Application

Just noticed this new webmail application called Hula. Here’s a excerpt from their project site:

Hula is a calendar and mail server whose goal is to be fun and easy to use, while scaling effortlessly from small groups to large organizations with thousands of members.
Hula is an open source project led by Novell

I’ve been using Squirrelmail for years now whenever I had the need to install any type of Webmail functionality. It has great features, it’s proven, and it’s actively maintained. The interface/GUI on the other hand has always seemed unsexy to me though. Hula actually looks very nice. It also seems to have some calendaring features as well as an integrated address book. While I haven’t installed it or even used it, it does look promising as an alternative to Squirrelmail…

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Building a NAS Using Old Hardware

I have a bunch of extra computer equipment just sitting around, including computers, hard-drives, etc. Well, I had a lot more before cleaning out our garage recently, but that’s a different story :-). While listening to one of my many podcasts, I heard the mention of a ‘software-based’ NAS that someone could use with old hardware.
Take a look at NASLite from Server Elements. They offer some streamlined distributions which are free to download, as well as paid versions with more features.
Basically, you grab an old computer, even an old 486, stick some hard-drives in it and boot from the floppy. A couple minutes later, after less than a minute of configuration, you have network attached storage. All your drives are now shares on your network, accessible by any other computers. Instant file-server, low maintenance. Beautiful!

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Creating a bootable Fedora DVD from CD ISOs

Since Fedora Core 2 will now be a 4-CD set, I decided to look into creating a DVD out of the CD’s in order to avoid having to carry around 4 CD’s in my laptop bag. Found my answer on the Fedora-Test_list today. A small script called “mkdvd” written by Chris Adams. His script can be found at

*Update* Another possible solution, while not as elegant, can be found at

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