#@linux

[iec-mediacoverage]

Ioto Sphere (12/03/2021)

Using Linux with critical applications: Like mixing oil and water?

...  But the functional safety standards such projects must adhere to have core objectives that must be complied with, including IEC 61508 (International Electrotechnical Commission, 2010), ISO 26262 (International Standards Organisation, 2018), and IEC 62304 (International Electrotechnical Commission, 2010) respectively for our industrial, automotive, and medical examples.

[edutechnolearning]

Ansible First Playbook

https://smarttechfunda.com/ansible-first-playbook/ The blog on creating a simple Ansible playbook structure, how to understand the YAML file, write the first playbook, and execute it. This blog is for beginners. 

[opshero]

Experience, all about it

Hello, I’m Horatiu, Romanian guy, IT oriented, DevOps enthusiast, friendly person, curious individual and this is my page.

I’m going to log here now and again when time allows things I did find out and experienced, things I think someone else might benefit from.

I do not offer any guarantees that what I post here is the norm of things, that I will post absolute truths but whatever I will post, it is something true for me, filtered trough my own experience.

Anyway, this are the 2 lines of generic intro.

[jeromyanglim]

Books useful to transitioning from Ubuntu to OSX

I found a few books at my library that provided a few additional ideas on using OSX for people coming from a Linux background. The following summarises some of the useful tips: ## [Mac for Linux geeks](http://www.amazon.com/Linux-Geeks-Experts-Voice-Source/dp/1430216506) A few interesting things included: * the history of Unix, Linux, and OSX. * a comparison of the file systems and file organisations of Ubuntu versus OSX * Advice on running Linux on OSX using dual boot or virtualisation options. * Examining system log files using the Console application (see in utilities). * [How to edit plist files using Xcode](http://osxdaily.com/2010/05/12/use-property-list-editor-to-edit-plist-files-for-free/) The book also discusses using MacPorts to get additional linux software. Important commands include: * `sudo port install foo` to install package `foo` * `sudo port uninstall foo` to uninstall package `foo` * `sudo port -u upgrade foo` to update package `foo` * `port search foo` to search for packages that match the pattern `foo` Other important commands include `selfupdate`, `installed`, `outdated`. See also this [usage guide](http://guide.macports.org/chunked/using.html). ## [Mac OS X Snow Leopard for Power Users](http://www.amazon.com/Mac-Snow-Leopard-Power-Users/dp/1430230304) A few interesting things that I learnt from this book: * [blacktree](http://secrets.blacktree.com) is a tool for manipulating hidden settings on OSX. * [Houdini](http://www.macupdate.com/app/mac/26729/houdini) is a simple program for toggling the visibility of hidden files in Finder. * [`mdfind` is so useful that I put together a separate post](http://jeromyanglim.tumblr.com/post/34813195534/using-mdfind-to-search-using-spotlight-on-the). Similar advanced searches can also be constructed using the search box in Finder. Scope can altered from the whole computer to the working directory. These searches can also be saved for later (here's a [tutorial from MacWorld](http://www.macworld.com/article/1132817/spotlight3.html)). * Built-in to OSX, selecting files and right clicking `compress` creates a zip archive files. For complex archiving needs (e.g., password protected zip files, uncommon archive formats) there is the free program [Unarchiver](http://wakaba.c3.cx/s/apps/unarchiver.html). * There is a chapter devoted to the many uses for Automator (see the [manual](https://developer.apple.com/library/mac/#documentation/appleapplications/conceptual/AutomatorConcepts/Automator.html). `launchd` is the OSX tool for scheduling actions (although `cron` still works). * The author recommends ScreenFlow for creating screencasts. * The author discusses using free DNS providers in one of the network profiles. To determine whether a given profile is faster, there is the free benchmarking tool [Google Public DNS](http://code.google.com/p/namebench/). In my case my ISP DNS (average response 118ms) was faster than Google Public DNS (197ms) and other Australian DNS providers.

[jeromyanglim]

What are the use cases for using the tee command?

* Write an intermediate stetp in a pipeline to a file * this might be useful when I want to do more than one thing to an intermediate step * Write output to the console and to a file * `grep '\*\*' README.md|tee unsorted.md | sort` * This is an example of saving a preliminary step in a pipeline * `grep` extracts lines with two consecutive stars and pipes the output both to a file `unsorted.md` using `tee` and to the standard in of `sort`. * `tee -a file` * appends to `file` rather than overwriting `file` * `grep @ README.md | tee emails` * This commands finds lines with the at symbol in README.md and sends the output both to the console and to the file `emails`

[jeromyanglim]

Understanding symbols for non-printing characters in Vim, cat, less, etc?

In Vim, `cat`, `less`, and various other programs, non-printing characters are sometimes represented in particular ways. The table in [Wikipedia on ASCII]( http://en.wikipedia.org/wiki/ASCII ) includes a table of ASCII control characters Here is an extract of some of the more relevant lines 000 0000 000 0 00 NUL ^@ \0 Null character 000 0001 001 1 01 SOH ^A Start of Header 000 0010 002 2 02 STX ^B Start of Text 000 0011 003 3 03 ETX ^C End of Text 000 0100 004 4 04 EOT ^D End of Transmission 000 0101 005 5 05 ENQ ^E Enquiry 000 0110 006 6 06 ACK ^F Acknowledgment 000 0111 007 7 07 BEL ^G \a Bell 000 1000 010 8 08 BS ^H \b Backspace[d][e] 000 1001 011 9 09 HT ^I \t Horizontal Tab[f] 000 1010 012 10 0A LF ^J \n Line feed 000 1011 013 11 0B VT ^K \v Vertical Tab 000 1100 014 12 0C FF ^L \f Form feed 000 1101 015 13 0D CR ^M \r Carriage return

[jeromyanglim]

What are tips for using the cat command effectively?

* To create input to command-line programs that don't read from files * `cat file | tr ...` * As I understand it, `tr` does not read from a file thus, `cat` provides standard input to `tr` * Various non-printing characters can be displayed * `cat -v file` * print file along with non-printing characters * `cat -T file` * prints tabs as `^I` * `cat -E file` * prints new line character as `$` * When is it useful to know about non-printing characters? * working out whether a file contains spaces or tabs; this is useful for creating tab or space delimited data files, and for ensuring that code complies with expectations (e.g., make expects tabs) * When files contain unwanted characters, cat can show what these are to enable removal * identifying existence of trailing spaces in lines