…with an open minded approach

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modprobe resume

modprobe, used in all linuxes

 

modprobe lsmod resume

modprobe lsmod resume

 

You can link or copy it, if you mention the author/source 🙂

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dpkg resume

dpkg, used in debian/ubuntu systems underneath APT

You can copy or link it if you mention the author 🙂

Yum resume

Without any further delay, here it goes

 

yum resume

yum resume

 

You can link or copy it, as long as you mention the author 🙂

Not complete, but it’s a good introduction to the main pieces

 

Drop a comment if you like it 🙂

Bash initialization files

This bash resume diagram is respectfully copied from http://www.solipsys.co.uk/new/BashInitialisationFiles.html

I’ll post it here before I need it again – its just great

RPM resume diagram

I’ve been reading a bit to take the LPIC-1 certificate – thought it was about time to get some official certificate stating that “all those hours around linux were not about playing games, it made you really learn somethings very usefull”. I already knew it, but the certificate is the most forefront way to show it to other people, and so here we go 🙂

The LPIC-1 seems quite accessible although you do need to read it over and study the details specific for the exam… the interesting content seems to be in LPIC-2 where the administration goes into more interesting services…

Well, the thing is I’ve taken my notes and made this resume-diagram, so I though better to share – here it goes

RPM

Not going to rewrite the excellent resumes that can be found in internet (such as http://bobcares.com/blog/rpm-basics/) so straight to the point – the resume diagram.

This resume is only about RPM, not including YUM (RPM is like Debian’s DPKG, while YUM is like Debian’s APT) and is saved as a SVG file and uploaded into a public github-repo so you can easily edit/improve/correct it – If you do so, drop a comment, it cheers up 🙂

Unfortunately WordPress does not allow to post SVG images (?!?) , so I’ve linked to a PNG version (its on github) – hope its usefull to you

RPM resume diagram

Sed info

Sed – An Introduction and Tutorial by Bruce Barnett – I really should post this up before I forget: it’s a sed resume that goes from-basic-to-deep features, progressively explaining what-does-what with examples… a really good reference for sed usage

 

If you’r into sed, take a look – it will be worth it

 

bash ternary-like comparisons…

Bash does not have a ternary operator ?: to do things like ” condition ? command-if-true : command-if-false ”

Its possible to do the same with “if”s but its not so neat and compact…

One hacky alternative which is possible in bash, is to do ” condition && command-if-true || command-if-false”, like so:

Hope it helps – if so drop a comment

bash trap and signals (or how to execute something at end of bash script)

In Bash scripts we can use “trap” to define handlers for capturing system-signals.

Apart from capturing system-signals (see a list of them with “kill -l”) bash also attends a non-standard EXIT signal, which is emitted just before the bash program exits.

In overall, being able to define handler for signals may be handy for example to grab “CTRL-C” or to clean temp-files before exiting

 

Running this twice, one first-time hitting CTRL-C and another time waiting untill it finishes, gives

 

 Refs:

Light overview of unix signals (indicating most common ones), in tutorialspoint

Bash with signals, from Bash Guide for Beginners

LinuxJournal article explaining that EXIT is not a real system-signal, but is synthesized by bash, with a very good overview of it all

find in subdirectories with limited depth

Better take note of this, so next time won’t need to search again for it: how to use find limiting the subdirectories-depth
Use “find –maxdepth <0=no-subdirs,1,2,…>

The info of “man find”, is not very understandable – goes into “find tests” and “arguments”… – so an example was what made it clear for me.

Hope it’s usefull for you too 🙂 – if so, drop a comment, it motivates me 🙂

Ruby: pass file descriptor between processes with unix sockets

The gist is (hopefully) self-explanatory – if not, read the header notes

Long story short – use UNIXSocket.send_io/recv_io to pass a file-descriptor between 2 processes.

Also, learned some Jruby limitations (?bug?):

  • Jruby cannot fork()
  • Jruby has UNIXSocket#send_io/recv_io broken, so its not possible to pass file-descriptors with Jruby… what a pitty…

And learned that working with Unix socket in ruby is soooo easy 🙂

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