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Shell Scripting Tutorial
May 17, 2014by Steve ParkerFREE Shipping on eligible ordersIn StockMore Buying ChoicesAuto-delivered wirelesslyHow to Create an RPM
Feb 24, 2016by Steve ParkerFREE Shipping on eligible ordersIn StockMore Buying ChoicesAuto-delivered wirelessly- by Steve ParkerAuto-delivered wirelesslyFREE Shipping on eligible ordersIn StockMore Buying Choices
Author Updates
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Blog postMy main Shell Scripting tutorial has moved to its own domain, at http://www.shellscript.sh/
This is easier to navigate, more tablet and mobile friendly, and generally more usable than before.
It also includes all the links to allow you to buy the content for yourself from Amazon (in eBook and Paperback), as well as for my full “Shell Scripting” book, as published by Wiley of New York.
And of course every page ends with a form to contact me with your feedback and com -
Blog postCreating an RPM package is incredibly easy, but somehow seems to be quite tricky to describe to people. I’ve written a short eBook (also available in Paperback) which comes with a free downloadable VirtualBox virtual machine image for working through the examples.
How to Create an RPM
I would love your feedback on this book, as it’s not a subject where there is necessarily a single “right” or “wrong” approach. What I’ve tried to cover here, is a minimal-effort guide to cr -
Blog postHere is a “minimal” guide to creating RPMs at http://steve-parker.org/rpm/ – I do plan to expand it further, but want to put something out there for now, for feedback at least, and to help people to make RPMs without necessarily having to dig deep into all the extra stuff that RPM can do for them.
I plan to make this into a more detailed and complete document, but for now, I’d love you to read this and tell me what you think.
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Blog postOne of the best ways to exploit “Shellshock” is via a CGI script executing Bash. Not many people write CGI scripts in Bash, but I do, and I published one in a book, too. So I’ve written about it: http://steve-parker.org/articles/shellshock/
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Blog postIn an article on ITworld.com, Sandra Henry-Stocker gives advice about writing efficient shell scripts.
Whilst a lot of the principles provided would appear to make sense, most of them actually do not make any significant difference, and some are entirely wrongly measured.
First, Henry-Stocker suggests replacing this script:
for day in Mon Tue Wed Thu Fri do echo $day touch $day.log done … with this one:
for day in Mon Tue Wed Thu Fri do if [ $verbose ]; then echo -
Blog postThis is just a quick note as it took me a while to find. I assumed that vmware_balloon.c would write stats into /proc, like most Linux kernel modules do.
That’s not how vmware roll, however. To find out how much RAM has been claimed by VMWare’s “Balloon” driver from within the guest OS itself, use the vmware-tools command:
# vmware-toolbox-cmd stat balloon 4460 MB
# -
Blog postUnix & Linux Shell Scripting Tutorial on Kindle
The Shell Scripting tutorial at http://steve-parker.org is now available natively on the Kindle! USA (amazon.com)
UK (amazon.co.uk)
Similarly, you can search for “B00C2EGNSA” on any Amazon site, or just go to http://www.amazon.COUNTRY/dp/B00C2EGNSA (where “COUNTRY” is .fr, .de, etc) for your local equivalent.
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Blog postMahmood Pahlevani has translated my Shell Scripting tutorial at http://steve-parker.org/sh/sh.shtml into Persian, at http://bashlinux.persiangig.com/stev/sh/index.shtml
Any feedback on this work is welcome here, I will pass on all praise to Mahmood,
Steve
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Blog postWhen a Solaris server is overloaded, this is one way to check what actual memory each process is using. Here I am restricting the checks to one user (“steve”) but by omitting the “-u steve” flag to ps, the whole system will be checked.
$ps -ea -o pid,rss -u steve | sort -n -k 2 | while read pid rss
> do
> echo -en "RSS : ${rss} Kb: "
> pmap -x $pid | tail -1
> done
RSS: 50104 Kb: total Kb 1384400 712744 494312 -
RSS: 669296 Kb: -
Blog postI have updated the cheatsheet at http://steve-parker.org/sh/cheatsheet.pdf – it’s still a single-page PDF, or a PNG at http://steve-parker.org/sh/cheatsheet.png, but it squeezes a bit more content in than the previous one had, and is slightly more Linux/Bash biased.
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Blog postWhether you’ve got an interactive shell session, or are writing a shell script, it is very difficult to be certain. It’s better to check for the capabilities that you require.
If you find yourself in a shell session, but don’t know what type of shell it is, there are a few ways to find out whether it’s Bourne shell, Bash, ksh, csh, zsh, tcsh, or whatever.
The simple answer is that you type in the command
echo $SHELL which should tell you the path to your current shell; -
Blog postIt is commonly said that Solaris 10 will not allow you to issue a rm -rf / command. Few get to try it, but it was being discussed in the office today, so I thought I’d try it on a virtual machine.
The classic rm -rf / gets the message “rm of / is not allowed” and a return code of 2. Some variations get the same, whilst others (such as cd /; rm -rf .) get no message, a return code of zero, but nothing happens. Here is a transcript:
$ ssh sunflare
Password:
Last logi -
Blog postIn case you hadn’t heard via other channels, my 564-page book, Shell Scripting: Expert Recipes for Linux, Bash and more is on sale now.
Paper books:
Amazon USA
Amazon UK
Also available at Barnes & Noble, WH Smiths, Waterstones, Supermarkets (online, if not in-store), and as the saying goes, every good bookshop (and some others too).
Kindle: Kindle
iPad / etc: iTunes
Nook: Nook
There’s also a Facebook page at facebook.com/shellscrip -
Blog postYes, it is perfectly possible. Do watch this YouTube Video
http://www.youtube.com/watch?v=WNPm3aKzPdg
Space Game
Space Invaders – written entirely in the Bash shell, in a 248-line shell script. The shell is often seen as old hat, hard to use, green screens and no interaction. In my new book, Shell Scripting (http://facebook.com/shellscript), I attempt to throw a new perspective on this; the shell can be used in lots of creative and imaginative ways.
The book also -
Blog postShell Scripting
My Shell Scripting book, due out on August 12th by Wrox, now has a page on Facebook: http://www.facebook.com/pages/Shell-Scripting/175263275869249. Feel free to “Like” it, and get the latest updates on the project. I have the final pages to proofread this week, ready to go to the printers. It’s looking like 576 pages, a little bit over the target of 504 pages, but close enough.
I will update the Table of Contents at http://sgpit.com/book/ once the page count is -
Blog postA few days ago I had to deal with my first ever real-life fork-bombed server.
By logging in to the console, I was somehow able to get a shell (one process). Having got that shell, even though I was root, it was difficult to be able to spawn other processes. It turned out that this was because we had restricted the CPU count on the kernel command line (maxcpus=2) so that a dual processor, 16-core machine had only one eighth of its processing power available. The dynamic change to the n -
Blog postAnother update on the upcoming Shell Scripting Recipes book. The writing is complete, the editing formatting and reviewing is now almost totally complete. In the meantime, Amazon’s UK discount has dropped to £4.80; Amazon.com is still offering a whopping $19.76 (40%) off the pre-order price. The trend seems to be that the prices are going back upwards towards the list price as the launch date (12th August 2011) comes closer so you may save more by ordering a copy now.
The full c -
Blog postWow, it’s been nearly two months since I last made a post about the upcoming book on shell scripting. I’m really sorry, I had intended to give much more real-time updates here. The book focusses on GNU/Linux and the Bash shell in particular, but it does cover the other environments too – Solaris, Bourne Shell, as well as mentions for ksh, zsh, *BSD and the rest of the Unix family.
In terms of page count, it is currently 89% finished. There is still the proof-reading to be done, and wh -
Blog postThis is just a heads-up that my Shell Scripting Recipes book is due out in August 2011.
I hope to publish more details here as things progress; for now, it is well on the way, but it is not too late for readers to contact me (steve@steve-parker.org) if there is anything that you see as vital for a Shell Scripting Recipes book which was maybe missing from some other book you saw.
http://amzn.com/1118024486
Part I covers Language and Usage; all of the concepts of the She -
Blog postBit of a cheeky one here – what does anybody want to know about these topics?
There is a book in the pipeline, and I have lots to say about all these things, but am very interested to hear what you think is easy / hard / intuitive / arcane / stupid about these commands and the whole job control side of Unix/Linux and the different shells.
lsof is great, but almost only GNU/Linux; fuser is good, but restricted in how much it actually tells you – you have to go digging into PIDs -
Blog postThe stats helper monkeys at WordPress.com mulled over how this blog did in 2010, and here’s a high level summary of its overall blog health:
The Blog-Health-o-Meter™ reads Fresher than ever.
Crunchy numbers A helper monkey made this abstract painting, inspired by your stats.
About 3 million people visit the Taj Mahal every year. This blog was viewed about 26,000 times in 2010. If it were the Taj Mahal, it would take about 3 days for that many people to see it.
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Blog posthttp://www.unix.com/tips-tutorials/20526-mtime-ctime-atime.html has a really good explanation of the different timestamps in a Unix/Linux inode. GNU/Linux has a useful utility called “stat” which displays most of the inode contents:
$ stat .bashrc
File: `.bashrc'
Size: 3219 Blocks: 8 IO Block: 4096 regular file
Device: fe00h/65024d Inode: 33 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 1000/ steve) Gid: ( 1000/ steve)
Access: 2010-10-07 01:11:21.000000000 +010 -
Blog postARNnet have an Interview with Steve Bourne
I believe you can write shell scripts that will run either in the Bourne shell or Bash. It may have some additional features that aren’t in the Bourne shell. I believe Bash was intended as a strictly compatible open source version of the Bourne shell. Honestly I haven’t looked at it in any detail so I could be wrong. I have used Bash myself because I run a Linux/Gnu system at home and it appears to do what I would expect.
I have near -
Blog postI have recently written a web service which creates Solaris 10 SMF manifests based on the information you give it.
It creates a ZIP file with the XML Manifest file, and the startup/shutdown script, based on what you tell it.
There is much more that SMF can do – create entire new runlevels, and so on – but this does the basic single-instance startup and shutdown stuff that /etc/init.d scripts did.
Feel free to go and check it out at sgpit.com/smf/
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Blog postPádraig Brady has some useful, if somewhat basic hints, at http://www.pixelbeat.org/cmdline.html. He has updated them to include more powerful commands at http://www.pixelbeat.org/docs/linux_commands.html.
Here are a few of my favourites (I have taken the liberty of slightly altering some of the code and/or descriptions):
From the original:
Search recursively for “expr” in all *.c and *.h files:
find -name '*.[ch]' | xargs grep -E 'expr'
Concatenate li
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