The pipe (|) character is used to combine multiple commands. A pipe is a temporary storage place where the output of one command is stored and then passed as the input for a second command. Pipes are used to run more than two commands from the same command line. The sort command is used to sort data. When you run the ls –l command, you will see a listing of the files in a directory with each file shown on a separate line. When you use a pipe after the command and then sort your results, you will sort the data listed on the screen by the list command. The…
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Simple Networking Commands
Troubleshooting the network is faster and more thorough when it is done using the command line. Here are some simple command-line utilities that can perform a variety of tasks that can help when administering many services and multiuser environments: Whoami lists the user you are currently logged in as from the command line. Who lists the users logged onto your system. Id shows a list of all defined users and groups whether they are actually logged in. Groups <userid> shows a list of all the groups a user is in. Whois lists ownership information for domains. Hostname lists the name of the computer you are currently working on. You can…
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Likewise Open 5.3 Supports Snow Leopard
Likewise 5.3 supports Snow Leopard at 32 or 64 bit! Likewise Open 5.3 is open source software that can be used to bind Mac OS X, Linux & Unix to Active Directory. Likewise Enterprise (which is not open source) starts with the Open client but allows leveraging Workgroup Manager or Active Directory Users & Computers to manage policies. If you haven’t already, check it out at www.likewise.com.
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DHCP Leases Expanded
DHCP provides IP addresses to clients. DHCP is critical to a number of Mac OS X Server technologies, most notably with NetBoot. In doing so, communications are comprised of 4 steps: Discovery, Offer, Acceptance, and Acknowledgment. In the Discovery step, a computer that needs an IP address sends a broadcast request to the environment. These typically remain local, although most routers will allow for configuring the gateway in such a way that UDP traffic is forwarded on to other subnets. The request also includes all of the options that the client will need, with options being anything beyond an IP address, each potential option with a numerical identifier per this…
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New Eggplant Now Available
Eggplant has released an update of their regression testing platform. And to make things easier for us, they’ve introduced Linux support, allowing you to regression test even more systems than before using a single, streamlined interface. This update also introduces support for Mac OS X 10.6. http://www.testplant.com/news_and_events/#recent_news
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Replica Trees & Tuning Open Directory
You have a fairly large Open Directory environment and you go to add the 33rd replica but you get a funny error that dserr doesn’t have listed. The reason is likely that a single Open Directory Master can only have 32 replicas. However, you can have 32 replicas on each replica (thus having a replica tree), ergo allowing for a total of 1,024 replicas and a master. So rather than bind that 33rd replica to a master, move to a replica tree model, trying to offload replicas in as geographically friendly a fashion as possible (thus reducing slap traffic on your WAN links) by repositioning replicas per site. Similar to…
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TLS + eDirectory
In order to bind a Mac OS X Server to eDirectory it’s more than likely going to give you fits if you don’t first augment the /etc/openldap/ldap.conf file. This is going to disable the TLS requirement. Before you do, if you can get TLS working with eDirectory then there’s likely no need to do the following but given that it is problematic if you’re having trouble, try this. To disable TLS, simply open it up and change the last line, for TLS_REQCERT to never and then killall DirectoryServices. You should then be able to bind to eDirectory (or another LDAP service) effectively. For further information on eDirectory integration, check out…
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Adding Color to & Customizing the Shell Prompt
As promised in the article on colorizing the terminal, let’s look at how to customize your bash prompt. First note that text as well as the following can be used in your string. a – ASCII bell d – date e – ASCII escape h – LocalHostName H – HostName j – number of jobs managed by shell l – basename of terminal device name n – insert a newline r – insert a carriage return @ – time in 12-hour HH:MM format A – time in 24-hour HH:MM format t – time in 12-hour HH:MM:SS format T – time in 24-hour HH:MM:SS format u – current user v –…
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Colorizing the Terminal
It really helps me to see different types of entries in the Terminal listed with different colors. I don’t go for listing everything that you can list as a different color though, as it starts looking a bit like a circus in Terminal when I do. If you want to colorize your terminal in Mac OS X there are two main ways to do so; both will require altering your .bash_profile (or creating if it’s not already there). To get started, go to your home folder from within Terminal and open .bash_profile from your favorite text editor. If it doesn’t exist then the text editor should create a new file…
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Virtual Private Clouds
VPN-Cubed was a solution that Amazon listed for some time, allowing users of EC2 or S3 cloud services to VPN their resources in Amazon’s cloud to their own offices. But Amazon recently went a step further with their own offering and now provide the Amazon Virtual Private Cloud. Pricing is based on a per-VPN connection, running at a nickel per hour that the VPN Connection is alive. Data transfer over the VPN is charged at a dime per gig into the cloud and between 10 and 17 cents per gig out of the cloud. There have been a number of concerns about security with regards to cloud services. The ability…