Sandra Henry-Stocker

  • Unix: More ways to spin the top command

    Posted April 13, 2014 - 2:12 pm

    The top command is one of the most useful commands for getting a quick glimpse into how your Unix server is performing, but stopping there might mean that you're missing out on a lot of interesting options.
  • Unix: Debugging your scripts

    Posted November 15, 2013 - 6:06 pm

    All kinds of things can go wrong with your shell scripts, but they don't have to. Let's look a some debugging tips that can help ensure your scripts run the way you intend.
  • Why I Love Unix

    Posted October 27, 2010 - 8:48 am

    Sandra Henry-Stocker's long-standing and largely happy relationship with Unix has been an interesting and rewarding trek. If she hasn't helped you to love Unix, let her try just once more.
  • Checking Your arp Entries

    Posted October 20, 2010 - 4:45 pm

    you to display the IP address to hardware (MAC) address mappings that a system has built so that it doesn't have to fetch the same information repeatedly for systems it communicates with.

  • Unix How-To: Checking on Collisions

    Posted October 13, 2010 - 5:04 pm

    One metric that helps gauge how well your network is holding up to the strain of busy users and applications is the number of packets that slam into other packets, generating what is called a "collision". Let's check out an easy tool for calculating the collision rate for a particular network interface.
  • Unix How-To: Nifty One-Liners

    Posted October 6, 2010 - 12:27 pm

    Today's collection of one-liners are sure to win some converts. There's nothing like a quick command that saves you a lot of trouble and just might impress your boss and coworkers that you're the cleverest person around.
  • Unix How-To: More Alias Quickies to Save You Time

    Posted September 29, 2010 - 3:50 pm

    Today's column is a grab bag of useful aliases that will save you some precious typing time. The sysadmins I know like to type as few characters as possible, so many of these are especially terse
  • Unix How-To: Making Better Use of Find

    Posted September 22, 2010 - 4:58 pm

    Find is not just useful for locating files, but also for doing things with the files once it finds them. You can find files based on numerous criteria -- their names, their owners, their size, etc. -- and you can then perform some operation on the files from simply listing them to changing permissions or analyzing their contents. You can also make the operation that you specify to occur only if you confirm that you want it to happen after you are prompted. Let's see how this works.
  • Unix How-To: Counting Anything

    Posted September 15, 2010 - 11:23 am

    A reader recently asked whether it was possible on Unix systems to count how many times a particular character appears on each line of text. "On Unix", I answered, "not only is just about anything possible, but there are usually half a dozen ways to do it".
  • Unix How-To: Quotes to Live By

    Posted September 9, 2010 - 11:10 am

    One of the things that really throws new Unix users is when to use quotes and which kind of quotes. Between single quotes, double quotes and back ticks, a person can start to feel that Unix is unnecessarily tricky.
  • Unix How-To: Checking Responses with ckyorn

    Posted September 1, 2010 - 8:11 am

    In last week's column, we looked at ckrange, a Solaris tool for validating numeric responses in scripts. A related command, ckyorn (for "check yes or no"), ensures that a user responds with some version of yes or no. With similar behavior to ckrange, ckyorn has the same advantages of simplifying your code so that you don't have to check whether a user has entered y, Y, Yes, yes, n, N, No, no or even YeS or nO.
  • Unix How-To: Checking Responses with ckrange

    Posted August 25, 2010 - 11:53 am

    One of the all too common coding mistakes leading to security vulnerabilities is the failure to validate all entered data for accuracy. A defensive developer will consider all input to be evil until proven otherwise. Anyone writing scripts on Solaris has a leg up when it comes to input validation -- the versatile and wonderfully handy ckrange command.
  • Unix How-To: Sudo without Passwords

    Posted August 18, 2010 - 5:39 pm

    How do you allow a particular user to run a particular command via sudo without having to enter a password? And why might you want to do this?
  • Unix Tip: Avoiding the Oops

    Posted August 11, 2010 - 7:32 pm

    Ever type "rm -rf dirname" and then realize you've just blown away the wrong directory? You can always alias the rm command to "rm -i", but let's look at a way that you can selectively determine which directories get that special "Are you sure you want to do that" treatment and which get quietly blown away.
  • Unix How-To: Give Me That Old-Time Security!

    Posted August 4, 2010 - 2:29 pm

    Even in the wild frontiers of today's Internet, good basic system security provides extremely valuable protection against security breaches. In today's column, I'm going to rant about some basic security rules of thumb that every Unix sysadmin ought to consider.
  • The Many Benefits of a Clean Desk

    Posted July 28, 2010 - 11:22 am

    One of the security policies that has taken hold across a wide range of businesses is the "clean desk" and often the "clean desk and clear screen" policy. Intended to keep both PII (personally identifiable information) and company proprietary information away from prying and wandering eyes, policies such as these have more advantages than first glance might suggest.
  • Unix How-To: Time-Saving Aliases

    Posted July 21, 2010 - 8:00 am

    Unix users are always looking for ways to make their systems a little easier to use or themselves more productive. In today's column, we'll look at a series of helpful aliases that might preserve a few of those brain cells for harder tasks.
  • Unix How To: Useful Shortcuts for Unix Geeks

    Posted July 7, 2010 - 2:13 pm

    In this week's column, we're going to take a look at several commands that might save you some time. Each of these commands is easy to use and easy to remember, but just far enough off the beaten track that you might not have used them before.
  • Review

    Book Review: PHP: The Good Parts by Peter B. MacIntyre

    Posted June 30, 2010 - 8:00 am

    When I first read this title, I had my doubts. Could a book that purported only to cover the "good parts" of a language really do justice to the language? Or would it be like telling your kids only about the "good parts" of sex, not mentioning the risks and responsibilities that go along with sharing intimacy? After reading the book, I'm impressed with the book and its approach. The book is good enough and substantive enough in its 150+ pages to get someone new to PHP both excited about the language and coding some useful PHP applications in short order.
  • The Big Move Toward Collaboration

    Posted June 23, 2010 - 11:20 am

    If only one thing impressed me at last week's FIRST conference in Miami, it was the extent to which the security community is moving toward collaboration. The FIRST community, now in its 23rd year, has long been about collaboration. Even so, this year's event highlighted companies, organizations and even international law enforcement deeply exploring the ways in which they can collaborate further and better to hold the line against the increasingly virulent opposition -- the bad guys.
  • Review

    Security Conference: My First FIRST

    Posted June 16, 2010 - 1:35 pm

    The 22nd annual Forum of Incident Response and Security Teams (FIRST) conference is meeting this week in Miami. While this is my first opportunity to participate in any FIRST activity, these conferences have obviously been ongoing since 1988. With a focus on detecting and responding to security incidents and the convention of moving to a different location each year -- last year in Kyoto, next in Vienna -- the conference in unsurprisingly international.
  • Unix Commands to Try When You're Bored

    Posted June 9, 2010 - 4:47 pm

    Not every Unix command sparks with novelty. After all, the OS has now been around for roughly forty years and the spark wears off. But there are some commands that pick up from where the basics run out of steam. Jump on a Linux box and try these out when you have a little free time. You might surprise yourself with some new tricks for your bag of Unix goodies.
  • Unix How-To: awk is still a very handy tool

    Posted June 2, 2010 - 2:38 pm

    Awk does a lot more than select a column from a file or an input stream. It can select columns from selected rows. It can calculate totals, extract substrings, reverse the order of fields and provide a whole lot of other very handy manipulations. Whether you squeeze your awk permutations onto the command line or prefer to build them into scripts, the language is clever and versatile and well worth using even as it joins the ranks of middle-aged computer utilities.
  • Unix How-To: DNS Logging

    Posted May 26, 2010 - 12:16 pm

    While it's generally preferable to let DNS servers to do their jobs quietly, you might sometimes want to turn on logging for troubleshooting or to view of kind of requests that are coming through the service routinely. To turn logging on, you just need to tweak the syntax in your configuration file and add some syntax that at first glimpse might seem fairly tricky.
  • Unix How-To: When Telnet isn't Telnet

    Posted May 19, 2010 - 1:48 pm

    The security dudes have been badmouthing telnet for a couple of decades now, reminding us that this old time tool for connecting to remote systems exposes our passwords to the snooping masses. But the telnet command itself still has some handy uses that shouldn't be abandoned.
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