Advice for everyday Unix systems administration and some clever ways to approach more challenging problems.
The arp command is a tool that allows 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.
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 ....
Today's column is a grab bag of useful aliases that will save you some precious typing time.
The find command 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 operati....
Counting how many times a particular character appears on a line of text, while not exactly straightforward, is easily done. If you take advantage of awk's ability to identify fields and its built-in field counter (NF), you can get very close.
In this week's column, I answer two readers' questions about working with Unix filenames. One asks how to easily remove all files in a directory except those that match a particular pattern. The other asks how to force the names of files ....
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 t....
Most people learn the mkdir command on the first day they start using Unix. Along with ls, cd and pwd, it's in the set of the most basic commands that everyone who ventures onto the command line on a Unix system ought to know. It generally takes....
The grep command can search for and list Linux files based on strings you are looking for and add the context of surrounding text.
The /etc/inittab file controls what happens whenever a Unix system is rebooted or forced to change run levels. Let's take a look at the configuration lines that tell your system what it's supposed to do when you hit that power button.
Port knocking is a method of opening ports on a firewall by trying to connect with a series of ports in a pre-determined order. The sequence of “knocks” acts like a secret access code
You can use nmap to quickly, easily and stealthily generate a listing of all systems on a particular subnet. And the process can be even simpler than building your own "ping everybody on this subnet" scripts.
Monitoring your data centers and building access points with CCD cameras can represent a boon to your overall security, but you need to know a little about camera terminology to make the best use of them.
You have probably used lsof from time to time, probably when tracking down some sort of problem. But maybe you haven't tried all of its permutations or looked at it just to get a deeper understanding of how some particular process works. Let....
The svccfg command on Solaris 10 systems allow you to modify the configuration of services. Using it, you can specify how particular services are run in much the same manner you would have made changes in the inetd.conf file on older versions of Sola....
