November 2007

I recently ran a training session teaching some Configuration Management (CM) personnel some of the basic UNIX/linux shell commands, along with some of the common ways Secure Shell (SSH) utilities can be used to move application code around during deployments. I created an outline for the class, which is reproduced below. In no way is this outline a complete reference for using shell commands and SSH for CM, but it introduces some of the basic utilities and commands that can be a part of a comprehensive CM architecture.

I) bash : a *nix shell
A) A shell is a command-line interface to an OS. There are lots of shells available in *nix (korne, bourne, etc.). bash tries to include the best features of each. Shells are related to DOS.
B) cygwin makes it work in Windows, along with most other “POSIX” compliant programs & utilities (including OpenSSH).
C) Some common shell commands (all of these work in the other shells as well):

i) cd : Change working directory.

(a) cd : By itself, cd puts you in your own home directory.
(b) cd /tmp/ftp_files : puts you in the /tmp/ftp_files directory. The leading “/” means start at the root or base of the file system, and traverse from there.
(c) cd myfiles : puts you in a subdirectory from your current location called myfiles. You could be anywhere in the file system and this form of the command will only look there for the named sub-directory.

ii) ls: List files.

(a) ls : lists files in current directory
(b) ls /usr/bin : lists files in sub-directory /usr/bin
(c) ls -l : lists files in “long” format, showing owner, permissions, sizes, etc.
(d) ls BAM* : Lists all files in current directory whose names start with “BAM”. The “*” is a wild-card.

iii) cp : Copies files from place to place, optionally with new name.

(a) cp thisfile.txt thatfile.txt : makes copy of thisfile.txt with name thatfile.txt.
(b) cp /tmp/sales.wks /home/jp : Copies file named sales.wks from directory /tmp to directory /home/jp (assuming this directory exists).
(c) cp /var/news/daily/* ~ : Copies all files (using a wild-card again) from directory /var/news/daily to the user’s home directory. The “~” by itself means current user’s home.

iv) grep : Matches a string with some source of text, often the contents of a file.

(a) grep error: *.log : Searches all files in the current directory whose names end in .log for any lines containing the text “error:”. If it finds any, it lists the file name along with the actual line of matching text.
(b) grep -i virus ~brian/* : Searches all the files in user Brian’s home directory for any file which includes the term “virus”. The “-i” switch makes the search case-insensitive. The “~” followed immediately by a user name is short-hand meaning the named user’s home directory.

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I first started this blog mainly as a way to promote stories and articles I’ve written that are published elsewhere. Soon enough, I also started using it as a scratch-pad for thoughts and ideas related to work. Just the simple act of typing them and posting them, where anybody can see them (even if few actually do) helps me to organize them and approach the problems and challenges more logically. Gradually, I also concluded that this would be a great place to put the entire collection of short stories that will eventually be published in a book entitled “Memoirs of a Horsetrader’s Son”. This blog is beginning to see some traffic now, and I’ve decided it’s time to add some organization, while evaluating some design enhancements. Look for a new theme shortly, as well as clearer boundaries between the stories, technical articles, and ‘Other’ - which will be a place to put random thoughts about anything. Until I start getting hit with a lot of spam, the ability to leave comments will remain open (although I do approve or reject them, I’ve never rejected any). If the blog gains in popularity, eventually it will attract spammers, and I’ll have to require captcha or registration or both. If you’re one of the (still mostly infrequent) visitors, welcome, and please feel free to leave feedback on anything you see here.

Joe

The “Could not create an instance of the CmdLib object. Please register the Microsoft.CmdLib component.” error message was because of certain web server extensions that weren’t installed. I think the SQL Server Reporting Server needed to be installed. In any case, we’re past that now.

Current problem: we’re running the sshd service with a Domain Admin ID. This works, but poses a security risk. I’m trying to get a test installation working where the service ID is a Domain User but not a Domain Admin. The service starts, but anyone connecting to it is dis-connected immediately after authentication. The debug message (running the server with full debug messages logged) states “fatal: setreuid 14153: No such process.” So again, looking for any pointers. I’ve been all over Google about this, nothing that seems to apply yet.

Actually, this article was published a few weeks ago, I just decided to mention it here while I’m working on my OpenSSH issues. It’s meant to be a light-hearted look at the scientific inaccuracies presented in the movie. Remember folks - it’s “Tongue-in-Cheek” - some people have really complained that I’m being too critical of a Kid’s movie.

Nine years after the final episode of Jerry Seinfeld’s successful sitcom aired on network television, Jerry returns to the screen as writer, director and producer of an animated family film, Bee Movie. Kids will no doubt like this movie, as cartoon movies featuring insects and animals have done exceptionally well over the last several years.

With the creative force of Jerry Seinfeld as a worker bee questioning the fact that his career choices seem limited, along with an appearance by Chris Tucker as a mosquito, there’s bound to be plenty of humor geared toward adults as well.

Aside from the whole anthropomorphic concept of talking insects, here is a countdown of the top five scientific inaccuracies presented in this movie.

#5. Bees Going to College

In this movie, Barry (Jerry Seinfeld) goes to college to learn to produce honey. In real life, it is primarily instinct that drives the bees to do what they do. At best, there may be some on-the-job training.

#4. Money

Not only do the bees producing honey get paid in this movie, Barry sets out to sue the human honey producing mega-corporations for stealing honey from the bees. In reality, there is no evidence that bees use any medium of exchange other than honey itself, unless you count pollen.

#3. Nuclear Family

Barry has a Mom and a Dad, who worry about the fact that their son may not want to follow in his father’s footsteps and become a honey-stirrer. In a real hive, there is only one “Mom” - the queen. The larvae and young bees are brought up by nurse bees (much like children in Hollywood). Contrast this with movies like Happy Feet from Warner Brothers, which also had singing and dancing animals, but at least presented a somewhat accurate representation of the life cycle of the penguins. Read More>>

Recently it was decided at the large State government facility where I work that Secure Shell (SSH) would be used to facilitate the deployment of application software to the servers. This approach has a number of advantages. All data transfers are encrypted. Key pairs can be used to automate the authentication, so the entire transfer can be scripted with Shell scripts. Plus, with SSH’s ability to execute remote commands, command-line utilities on the target server could be utilized to stop and start services and web sites as necessary during the deployments.

Since most of the target servers that host our applications are Windows servers, that meant installing a 3rd party SSH server. The State opted for OpenSSH, the Open Source SSH implementation. To get that to work in a Windows environment requires Cygwin, a “linux-like” shell environment that runs under Windows. Getting this to work in a default environment is a snap. Getting it to work in a complex environment which includes Active Directory, domain controllers, and Group Policy Objects has proved to be quite a challenge. We are making progress, and I’ll probably write up the entire process in a “How-To” article in the near future. In the mean-time, I’m struggling with one weird error trying to stop and start web-sites.

We are using a command-line utility named iisweb.vbs to stop and start the services. The ID we are running the script under appears to have the necessary privileges to use this utility (being a Domain Admin), but when it executes, it errors out with the message “Could not create an instance of the CmdLib object. Please register the Microsoft.CmdLib component.” The funny thing is, this was working until yesterday, when the server teams re-built the server in order to re-partition the drives. Any help would definitely be appreciated.

Jp

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