Introduction to Linux

University of Bristol - Advance ComputingResearch Centre

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Operating SystemsProgram running all the timeInterfaces between other programs andhardwareProvides abstractions (common interfaces,e.g. filesystems)

You may know

WindowsMacOSiOSAndroid

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UNIXAn operating system originating at BellLabs. circa 1969 in the USA

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User InterfacesCommand LineGUI - Graphical User Interface

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Kernels and ShellsThe kernel is the core of the operatingsystemThe shell is the interface between the useraand the operating system

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LinuxA version of UNIXWritten by Linux Torvalds when he was anundergrad in FinlandFree (libre, gratis)One OS from Desktop -> SupercomputerTechnically just the kernelDistributions bundle kernel, GNU tools andextra softwareBlueCrystal Phase 3 runs CentOS 6

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Linux PhilosophyKit of partsOne small thing does one thing wellSmall utilities can be joined together toperfom more complicated tasks

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Bits and Pieces

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At First...

$ ls | wc -l

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But Later...

tr -cs A-Za-z '\n' | tr A-Z a-z | sort | uniq -c | sort -rn |

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Logging OnWe'll be working on the HPC (Blue Crystal)

Start PuttyLog in to bluecrystal phase 3:

train##@bluecrystalp3.bris.ac.uk

Where ## is your account number, ietrain01

First commands, get the example data:

cp -r ../intro_to_linux .cd intro_to_linux

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Filesystem Hierarchy

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DirectoriesPathnames and /Finding where you are (pwd)Changing to a different Directory (cd)The Directories . and ..Home directories (~)

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Tasks 1find out where you arewhat is pathname one level above (gothere)go back to your home directory (prove it)

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New Files and DirectoriesListing files and directories (ls)Making Directories (mkdir)

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Tasks 2What is in your home directory?What is on one level above?Make a new directory in your homedirectory ( give it a one word name)

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File ManipulationCopying Files (cp)Moving Files (mv)Removing Files and directories (rm)

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Tasks 3copy example.txt to another filenamerename your new file to something elsemove you new file in to the directory youcreated earliermake another copy of example.txtdelete your second copy

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Examining File ContentsDisplaying the contents of a file on thescreen (cat, less)The first lines in a file (head)The last lines in a file (tail)Searching the contents of a file (grep)Counting with grep (-c)UNIX is case sensitivegrep -i

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Tasks 4What is in example.txtWhat are the first 10 lines of example.txtWhat are the first 15 lines of example.txtWhat are the last 2 lines of example.txtRead through the whole of example.txt apage at a timeFind all the lines that mention "GNU"Count the number of lines that have theword "Linux" (in any capitalisation)

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FilenamesWildcards

? Any character* More Than One Character

Filename Conventions (e.g. .c)

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Tasks 5list all the two letter commands in /usr/binlist all the commands with "to" in theirname

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Getting Helpmanman -kGoogle (other search engines are available)

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Tasks 6Read the man page for headPick a random command from in /usr/binand read it's manpage

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Maniputaing Filessortuniq

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RedirectionRedirecting the Output

> (overwrites)>> (appends)

Redirecting the Input<

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Tasks 7sort the file authors into alphabetical orderfind the list of unique authorsfind how many time each appears in theoriginal list

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Pipes and PipelinesTake the standard output of one commandand feed it in to the standard input of thenextUses the pipe (vertical bar) symbol |No intermediate files!

Efficient

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Tasks 8without using intermediate files...

sort the authors filefind the count of unique authorsput that list in to numerical order

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Text Editorsnot Wordvim is mentioned a lot but don't use just yet

we recommend nano

^O to save^X to exit

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Task 9add some more authors to the authors filererun the previous analysisput the analysis command pipleine in to afile called author_count

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Any Questions?

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Resources - Where to practisemacOS users can use the terminalWindows10 has Windows Subsystem forLinuxDepartmental resourcesEligible users can apply for an account onthe ACRC clustersCloud vendors provide trial subscriptions

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Resourceshpc-help@bristol.ac.ukACRC Website -https://www.bristol.ac.uk/acrc/http://swcarpentry.github.io/shell-novice/http://www.ee.surrey.ac.uk/Teaching/Unix/

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CreditsLicence

This work is licensed under a CreativeCommons Attribution-ShareAlike 4.0International License.

Based on previous versions by

Rob Thomas - ACRCUniversity of Surrey

Image Credits

Redirects and Pipes (c) SoftwareCarpentry CC-BY-4.0 37 / 37