BashPitfalls - Greg's Wiki
Version. Date. Description. July 28, Third Internet Edition. July 6, all the security problems and want to give Linux a try. That's fine. All are negeriku.info ○ The GNU how paste operates, we will perform some surgery on our negeriku.info file to pro-. Problem. The problem is the unquoted variable in echo $result >>./negeriku.info When you have an unquoted variable, all whitespace (including. Well I thought all those libraries were included in the edition of Linux I .. hobbes, POST beeps (if PC speakers are plugged in) are the primary way to diagnose major system problems, Assid, the latest in ubuntu im in negeriku.info my system date format is Doctor is now known as Guest
There were often at least a few people, the holders of knowledge, who knew how everything worked, and I mean everything. Every application, every piece of network gear, and how every server was configured -- these people could save a business in times of disaster.
Now look at what we've done. Knowledge is so decentralized we must invent new roles to act as liaisons between all the IT groups. Architects now hold much of the high-level "how it works" knowledge, but without knowing how any one piece actually does work. In organizations with more than a few hundred IT staff and developers, it becomes nearly impossible for one person to do and know everything. This movement toward specializing in individual areas seems almost natural.
That, however, does not provide a free ticket for people to turn a blind eye. Specialization You know the story: Company installs new application, nobody understands it yet, so an expert is hired. Often, the person with a certification in using the new application only really knows how to run that application.
Perhaps they aren't interested in learning anything else, because their skill is in high demand right now. And besides, everything else in the infrastructure is run by people who specialize in those elements. Everything is taken care of. Except, how do these teams communicate when changes need to take place? Are the storage administrators teaching the Windows administrators about storage multipathing; or worse logging in and setting it up because it's faster for the storage gurus to do it themselves?
A fundamental level of knowledge is often lacking, which makes it very difficult for teams to brainstorm about new ways evolve IT services.
- Your Answer
- 2. cp $file $target
- 2. How can I store the return value and/or output of a command in a variable?
The business environment has made it OK for IT staffers to specialize and only learn one thing. If you hire someone certified in the application, operating system, or network vendor you use, that is precisely what you get.
Certifications may be a nice filter to quickly identify who has direct knowledge in the area you're hiring for, but often they indicate specialization or compensation for lack of experience. Resource Competition Does your IT department function as a unit?
Even person IT shops have turf wars, so the answer is very likely, "no. One IT budget gets split between all these groups. Often each group will have a manager who pitches his needs to upper management in hopes they will realize how important the team is.
Slightly Skeptical View on Enterprise Unix Administration
One strategy is to illustrate a doomsday scenario. If you paint a bleak enough picture, you may get more funding. Only if you are careful enough to illustrate the failings are due to lack of capital resources, not management or people. A manager of another group may explain that they are not receiving the correct level of service, so they need to duplicate the efforts of another group and just implement something themselves.Downsides of being a doctor!
On and on, the arguments continue. Most often, I've seen competition between server groups result in horribly inefficient uses of hardware. For example, what happens in your organization when one team needs more server hardware?
Assume that another team has five unused servers sitting in a blade chassis. An OFM tends to educate the user about the Unix filesystem in some subtle, but definitely psychologically superior way. Widespread use of OFMs in Europe, especially in Germany and Eastern Europe, tend to produce specialists with substantially greater skills at handling Unix and Windows file systems than users that only have experience with a more primitive command line based navigational tools.
And yes, cd navigation is conceptually broken. This is not a bizarre opinion of the author, this is a fact: People using command line know only fragments of the file system structure like blinds know only the parts of the elephant. Current Unix file system with, say, 13K directories for a regular Solaris installation, are just unsuitable for the "cd way of navigation"; 1K directories was probably OK. But when there are over 10K of directories you need something else.
Here quantity turns into quality. The page provides rather long quotes as web pages as web pages are notoriously unreliable medium and can disappear without trace.
That makes this page somewhat difficult to browse, but it's not designed for browsing; it's designed as a supplementary material to the university shell course and for self-education.
This is a really excellent site with the good coding practice section, some interesting example scripts and tips and tricks A complementary page with Best Shell Books Reviews is also available. Although the best book selection is to a certain extent individual, the selection of a bad book is not: Still the shell literature is substantial over a hundred of books and that mean that you can find a suitable textbook.
Please be aware of the fact that that few authors of shell programming books have a broad understanding of Unix necessary for writing a comprehensive shell book. IMHO the first edition of O'Reilly Learning Korn Shell is probably one of the best and contains nice set of examples the second edition is more up to date but generally is weaker. It does not cover ksh93 but it presents ksh in a unique way that no other book does. Still one needs to understand that Unix shells are pretty archaic languages which were designed with compatibility with dinosaur shells in mind and Borne is a dinosaur shell by any definition.
Designers even such strong designers as David Korn were hampered by compatibility problems from the very beginning in a way it is amazing how much ingenuity they demonstrate in enhancing Borne shell; I am really amazed how David Korn managed to extend borne shell into something much more usable and much loser to "normal" scripting language.
In this sense ksh93 stands like a real pinnacle of shell compatibility and the the testament of the art of shell language extension. That means that outside of interactive usage and small one page scripts they generally outlived their usefulness.
That's why for more or less complex tasks Perl is usually used and should be used instead of shells. While shells continued to improve since the original C-shell and Korn shell, the shell syntax is frozen in space and time and now looks completely archaic. There are a large number of problems with this syntax as it does not cleanly separate lexical analysis from syntax analysis. In a way, he proved to be the most influential bad language designer, the designer who has the most lasting influence on Unix environment that does not exonerate the subsequent designers which probably can take a more aggressive stance on the elimination of initial shell design blunders by marking them as "legacy".