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Wicked Cool Shell Scripts
Chapters are divided into an array of topics sure to catch the attention of any UNIX based system user: The Missing Code Library, Improving on User Commands, Creating Utilities, Tweaking Unix, System Administration: Managing Users, System Administration: System Maintenance, Web and Internet Users, Webmaster Hacks, Web and Internet Administration, Internet Server Administration, Mac OS X Scripts, and Shell Script Fun and Games.
In true "cookbook" fashion, each hack is numbered and divided into The Code, How It Works, Running the Script, The Results and Hacking the Script. Throughout, the author clearly describes the syntax and functionality of each script, often with additional notes in How It Works detailing the syntax process and interesting asides. But Hacking the Script is what gives Wicked Cool Shell Scripts true value; where applicable, the author uses this section to describe script modifications to achieve a variety of alternative real world, practical results. This additional section alone easily triples the total number of scripts the reader is exposed to.
This book enables the reader to get "up close and personal" with their UNIX based system and explore the possibilities afforded by becoming intimate with the command line interface. The reader will find themselves easily propelled into the world of scripting, thanks entirely to Dave Taylor's ability to take what some might describe as a fairly dry topic and translate it into a logical and user friendly construct. Just reading through the table of contents is inspiring and intriguing; did you know you could write a script to retrieve movie info from IMDb? or track the value of your stock portfolio? or that you can use a very simple script to check spelling on your web pages?
Sysadmins and webmasters will find this book fundamentally critical to day-to-day operations; there are dozens of invaluable, customizable scripts highlighted in this book to enable professionals to save time and add simple, elegant solutions to annoying issues in their work environment. User account management, rotating log files, cron scripts, web page tweaks, apache passwords, synchronizing via ftp, etc. are all eminently useful and tweakable.
Geeky home users will discover they can use these scripts to work with files and directories, create spell-checking utilities, calculate loan payments, create summary listings of their iTunes libraries, and of course, play games. Many of the sysadmin scripts would also be of interest to the power user: analyzing disk usage, killing processes by name and backing up directories, to name a few. Both types of users will find this book inspiring and truly fun!
One of the secret pleasures of a technical book reviewer is finding those wonky bits of code that suffer from misplaced or missing punctuation, misspelled words and other basic typographic errors inherent in the book publishing process. I randomly selected many of these scripts to try out in the process of doing this review and...dang, haven't found any errata yet. But be sure to check out the errata page on Dave Taylor's web site for any that more astute readers may find (there were none, as of this writing).
Also be sure to take a closer look at Dave's shell script library, which lists additional scripts that didn't make the cut for the book. As convenient as it is to download the entire script library, I would like to stress the value of buying the book, which will provide you with invaluable instruction and guidance in understanding the syntax of the scripts and it also illustrates how making small but significant tweaks can modify the output to match your specific needs.
(A special nod of appreciation to Dave Taylor's Tintin references!)
You can purchase Wicked Cool Shell Scripts - 101 Scripts for Linux, Mac OS X, and UNIX Systems from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
Get a copy of Windows Admin Scripting Little Black Book, or something similar. I got a copy of the first edition at Borders for $5, you may find similar on ebay or half.com.
If the script is not working as you want, put a
on the fist line and on the last line.You will see the exact execution path and variable expansion, very neat for debugging
for the last time people, I am "frodo from middle eaRTH", not "middle eaST".
You might want to read imdb's robot.txt before using wget.
(i) Many people, like myself, don't know perl, and don't see the point in learning when shell scripts are perfectly adequate for their purposes.
(ii) Sometimes it's just easier. viz. this quote from bash.org:
Jurisprudence Fetishist Gets Off On A Technicality --theonion.com
I don't know if such a book (or chapter in a book) exists, but here are some links:
Have fun...
Cygwin is your friend. For just one example, you can write a script that uses sed to extract information from the filenames of your mp3z and feed the results into id3ed to tack on an ID3 tag. Try doing that with a batch file.
20 January 2017: the End of an Error.
usually the really important scripts are running /bin/sh - a STATICALLY compiled binary of a shell that is pretty much everywhere.
why not dynamically compiled? Well if your glibc barfs all dynamically compiled binaries barf with it - including perl, and including any shells that you use to start up your system. With a statically compiled shell to handle all of those startup scripts you can boot linux without glibc working, and you probably have enough of a system still running to get things fixed. with a dynamically linked startup file interpreter, when glibc or something glibc depends on goes, your whole system goes, single-user mode and all.
Besides, while perl can execute system commands and make decisions based on input, i think the shell is a better tool for things like this. sh and bash were designed to do startup scripts (among other things) and they do them well. why fix what isn't broken? shell scripts work, and they can do anything you'd need them to do during startup.
Here's other stuff I have grouped by sections in my .cshrc
First, I have my shell variables. The comments say what they do. The most important one is autolist.
Second, bindkeys are pretty neat. I rebind the up and down arrow keys. By default they scroll up and down one at a time through the history. You can bind them to search the history based on what you've typed so far.
Third, completes allow for customizing tab completion. When I change directories, tab only completes directory names. This also works for aliases, sets, setenvs, etc.
Fourth, I have all my aliases. I had to cut a bunch because of the lameness filter.
The ultimate goal of science is to unify all forces of nature to a single law that can be silk-screened onto a T-shirt.
If you like scripting and all things Unix I highly recommned Unix Power Tools. I bought a copy last month. All the things about Unix that could not necessarily fill an entire book other their own nicely packaged together.
UNIX/Linux Consulting
Another good book is The Unix and X Command Compendium Shows shell commands, and explains what they do. A very good Unix reference book.
The shell helper that I am totally lost without is one that adds directory history to bash and ksh. You can find it here: _cd
I guess I never really got the idea of a stack of dirs being useful, since I seem to bounce around more at random than anything else. I prefer to have a cache of places I've recently been.
Bonus puzzle for slashdot readers: using the cd with history function, what directory is this command likely to take me to?
That's true, but the fallacy is that you're assuming Windows should be scripted in the same fashion as *nix. That's simply not the case. Batch/Command scripting is nice for small bits, and can actually be fairly powerful in an obtuse sort of way, but the real power in automating Windows comes by using the Windows Scripting Host, JScript or VBScript, and all of the ActiveX/COM interfaces into the functionality of the OS and other applications. A classic example is iterating through users. In *nix, you write a shell script to parse through /etc/passwd. In Windows, you write a jscript to instantiate the objects that deal with Active Directory, and iterate through user objects (each of which you can perform actions upon, wherein *nix you'd have to invoke other applications). One approach is not necessarily "better" than the other, but you can't assume that your *nix administration experience will directly translate into Windows administration. You'd laugh if a Windows admin felt the reverse was true. What really gets me is when people complain about Windows not being automation-friendly because they're used to *nix scripting. Yes, you cannot pipe notepad.exe into winword.exe, for example, but Word has a very rich automation interface that you can hook into and use from a simple JScript.
What? Try running "help del" from a cmd.exe window some time. Also, look at "help rd". If you want to remove a directory tree, you use the "remove directory" command. "del" deletes files. "rd" deletes directories (and can delete files within directories if you tell it to).
Consider cmd.exe to be the functional equivalent of csh. It's a decent interactive shell, and has some good functionality (especially later versions of cmd.exe in win2k and xp), but you'd have to be nuts to do any extensive scripting with it. Just as you'd pull out bash or perl to do more complex tasks in *nix rather than using csh, you should use WSH in Windows for more complicated tasks.
From the site:
This tutorial assumes no previous knowledge of scripting or programming, but progresses rapidly toward an intermediate/advanced level of instruction (...all the while sneaking in little snippets of UNIX wisdom and lore). It serves as a textbook, a manual for self-study, and a reference and source of knowledge on shell scripting techniques. The exercises and heavily-commented examples invite active reader participation, under the premise that the only way to really learn scripting is to write scripts.
Together, we will drive the rats from the tundra.
Well, I think Silent Bob (garcia) is directly attacking me as the author of these fine tools: Linux tools for geocaching
I do know Perl as well as all of the original Unix tools: awk, sed, and of course my favorite: shell.
The short and main explanation is that shell/awk/sed lend themselves very well to what is known as the "Unix tools" approach. Its a way of thinking using a small set of core tools that pays big rewards in productivity.
In the case of my geocaching tools, two things were plainly obvious to me at the start. 1) I would be scraping the pages with curl, because there is no better and easier tool for that job, and 2) gpsbabel would be a main part of almost every tool because it knows how to work with a bajillion waypoint formats. So the onl;y question after that is which language to use to glue those commands together. Shell, awk, and perl can all do that. I used shell to tie it all together because that is what shell is best at.
In a few of the tools, geo-map in particular, I did make a mistake in the glue choice. My excuse there is that it evolved far beyond its original design goals. So it ended up requiring a lot of floating point calculations and therefore I had to run several mini-awk scripts within it. If I were to rewrite it today, I would make it a pure AWK script. Why not perl? Because, IMHO, awk has the cleanest syntax of any of the scripting languages.
So, then, when *would* I use perl? In general, I select perl when 1) there is a pre-written module that does a job that would be hard to do with shell/awk/sed, and 2) the use of that module is truly necessary. That second point is very important to me. The mere existance of a Perl module does not necessarily mean its the best or fastest way to solve the problem.
Perl was the language of choice for "Belle", which is a 4000 line IRC robot I coauthored for use in my daytrading activities. The IRC module was what tipped the scale for Perl in that case.
Another problem with perl modules is that using them guarantees that you will lose some percentage of potential users of your program. Having to find and install additional packages puts many people off. I try to make my scripts completely self-contained (including usage doco) so that people don't have to go thru these hassles.
Anyway, you can argue with any of my points, but what you can't argue with is that I have the largest set of command line tools for geocaching that work, regardless what my language choice was.
-Rick
The trick with Windows is that you can do many of these same things, but this power comes from doing it in WSH or VB (or C/C++ or an ASP or whatever language you're comfortable with. I've even done it in Perl.) You use the COM interfaces of the shell object to enumerate through directory trees and files. You can stream each of those files into the COM interface of another program that accepts streams. You can search, you can pipe stuff all over, and you're not limited to a single instance of stdin, stdout and/or stderr.
It's not unlike shell scripting, it's just a different language. Each application is able to expose whatever it feels is most important in whatever fashion it thinks is best. DevStudio, for example, lets the scripting host user get to the workspace, the project, and any of the tools.
The biggest problem I have with it is that stdio is not "guaranteed" to be supported by every application under Windows. stdio is the glue that binds all the UNIX utilities together. That's the beauty of stdio -- as the sole mechanism for I/O for most tools, it became the defacto application interaction interface. Windows doesn't have that: most Windows apps don't offer any automated IO at all. And some of the ones that do seem to have interfaces pasted on after the fact. But the ones that do expose properties and methods via COM are easy to access, and easy to control from anywhere. And using the interfaces tends to remove the ambiguities: in UNIX if you're using 'cut' to parse a phone list but the name field sometimes contains commas, you end up hacking around solutions to make them work. A COM-based solution would provide an interface containing a Name field.
Windows is not alone in this limiation, either. UNIX suffers from a similar problem: how do you meaningfully pipe data to and from an X window, or even to a curses app? Is it consistent between apps? Most apps I am familiar with that offer such features in their applications had to have code added to actively support a meaningful commandline interface to their programs through the use of dozens of command line switches. Without this sort of code, using stdio to parse the output of a curses-based application becomes a tedium of screen scraping.
Don't get me wrong: I have a bevy of UNIX-like command line utilities for Windows, I use Cygwin and bash when I need to (although the file system mapping is worse than I could have imagined), and I will fire up a CMD script long before I think to write it as a VB or C++ program. I'm far more comfortable with the sh-style tools -- I grew up with them.
I'm not saying stdio is better or worse than using the COM interfaces of Windows; I'm just saying it's "different." And you certainly shouldn't be reinventing the wheel to script up utilities in Windows.
John