High Performance Computing Introduction to Unix

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High Performance Computing Introduction to Unix

• Robert Whitten Jr

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Welcome!

• Todays Agenda
• Questions from last week
• File systems
• Shell scripting

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From last time

• Send me that email if you havent already
• whittenrm1_at_ornl.gov
• Apply for an account
• http//www.nccs.gov/user-support/access/account-re
  quest/
• Download and install cygwin (Windows users only)
• Download putty.exe (Windows users only)

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Shell scripts

• Programs to help automate recurring task
• Text files that are interpreted by shell program
• Interpreted vs compiled languages

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Shell script basics

• Comments
• Values
• Variables
• Arrays
• Selection
• Loops

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Shell script - comments

• Comments are not executed
• Useful in documenting you scripts
• comment everything to right
• Exception is very first line of script
• !/bin/bash

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Shell script - values

• Values are object used in your script
• String values bobby
• Numerical values 94
• String values are quoted
• bobby just a string, no processing
• bobby a string, but with processing
• bobby - execute this string and get output back
• Numerical values can have math performed on them
  using the special form (( ))
• x((22))
• echo x
• 4

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Shell script - variables

• Use variables when the values may change
• Example
• xhello
• echo x
• hello
• x5
• echo x
• 5
• If you want to treat a string as a variable
• let x55

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Shell scripts - arrays

• Arrays are variable with 1 or more elements
• x(a b c d)
• echo x0
• a
• echo x
• a
• Wheres everything else?
• echo x_at_
• a b c d

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Shell scripts - selection

• If this, then that, else something else
• if then elif fi
• !/bin/bash
• if 1 'hello'
• then
• echo hello yourself
• elif 1 'howdy'
• then
• echo howdy to you too
• else
• echo nobody home
• fi

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Shell script - loops

• For this number of times, do something
• for name in bobby doug frank do
• echo name
• done
• let x1
• until x -eq 10 do
• echo x
• let xx1
• done
• let x1
• while x -ne 10 do
• echo x
• let xx1
• done

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Homework

• Send an email to me if you havent
• whittenrm1_at_ornl.gov
• Homework 1 will be posted soon to website
• Make sure cygwin is installed and working
  (Windows)
• Make sure you can get to a terminal window (Mac)

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Questions?
http//www.nccs.gov
Oak Ridge National Laboratory
U. S. Department Of Energy 13