Page Comparison

This page should serve as a reference for the many "things Linux" we use in this course. It is by no means complete – Linux is **huge** – but offers introductions to many important topics.

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• Macs and Linux have a Terminal program built-in
• Windows options:
  • Windows 10+
    • Command Prompt and PowerShell programs have ssh and scp (may require latest Windows updates)
      • Start menu → Search for Command
    • Putty – http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html
      
      • simple Terminal and file copy programs
      • download either the Putty installer or just putty.exe (Terminal) and pscp.exe (secure copy client)
    • Windows Subsystem for Linux – Windows 10 Professional includes a Ubuntu-like bash shells
      • See https://docs.microsoft.com/en-us/windows/wsl/install-win10
      • We recommend the Ubuntu Linux distribution, but any Linux distribution will have an SSH client

Use ssh (secure shell) to login to a remote computers.

# General form:
ssh <user_name>@<full_host_name>

# For example
ssh abattenh@ls6.tacc.utexas.edu

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• here are some good ones:
  • a good general one: https://www.regular-expressions.info/
  • Ryan's tutorials on Regular Expressions: http://ryanstutorials.net/regular-expressions-tutorial/
  • RegexOne: http://regexone.com
  and a perl regex tutorial: http://perldoc.perl.org/perlretut.html
  • perl regular expressions are the "gold standard" used in most other languagesExpressions: http://ryanstutorials.net/regular-expressions-tutorial/
  • RegexOne: http://regexone.com
• and a perl regex tutorial: http://perldoc.perl.org/perlretut.html
  • perl regular expressions are the "gold standard" used in most other languages

perl pattern matching

If grep pattern matching isn't behaving the way I expect, I turn to perl. While Perl, like awk, is a fully functional programming language, Here's how to invoke regex pattern matching from a command line using perl:

perl -n -e 'print $_ if $_=~/<pattern>/'

sed pattern substitution

The sed (string editor) command can be used to edit text using pattern substitution.

sed 's/<search pattern>/<replacement>/'

While sed is very powerful, the regex syntax for its more advanced features is quite different from "standard" grep or perl regular expressions. As a result, I tend to use it only for very simple substitutions, usually as a component of a multi-pipe expression.

perl pattern substitution

If I have a more complicated pattern, or if sed pattern substitution is not working as I expect (which happens frequently!), I again turn to perl. Here's how to invoke perl pattern substitution from a command line:

perl -p -e '~s/<search pattern>/<replacement>/'

Parentheses ( ) around one or more text sections in the <search pattern> will cause matching text to be captured in built-in perl variables $1, $2, etc., following the order of the parenthesized text. The capture variables can then be used in the <replacement>.

Field delimiter summary

Be aware of the default field delimiter for the various bash utilities, and how to change them:

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Examples:

ls -l ~/.bash_history

ls -l /usr/bin/ls

ls -l -d ~/local (-d says to list directory information, not directory contents)

Copying files between TACC and your laptop

Anchor
Copying_files_to_from_TACC Copying_files_to_from_TACC

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• Greg's Bash Guide
  • The Guide: http://mywiki.wooledge.org/BashGuide
  • FAQ: http://mywiki.wooledge.org/BashFAQ
  • Pitfalls: http://mywiki.wooledge.org/BashPitfalls
• Ryan's Tutorials on Bash Scripting: http://ryanstutorials.net/bash-scripting-tutorial/
• CBRS short course workshop wikis (developed by Anna)
  • Introduction to Unix: https://wikisutexas.utexasatlassian.edunet/wiki/display/CbrsIntroUnix/
  • Intermediate Unix: https://wikisutexas.utexasatlassian.edunet/wiki/display/CbrsIntermUnix/
  • You won't have access to the small compute cluster they use, but you can download the example files and manipulate them in your own Linux or Unix environment.

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