GNU Linux Tutorial

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GNU / Linux Tutorial

• SERC Students' Activities
• Aug 26, 2006

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Topics

• Background
• Starting off with GNU / Linux
• Programming Environment
• Text Processing
• Installing Packages
• Editors
• Introduction to Scripting in Bash and Perl
• Hands-on session

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Starting off with Linux

• Has always been a command-line based system
• Currently very good GUI support
• Many distributions of linux like SuSe, Gentoo,
  Fedora, Debian
• Distributions differ in the number of
  customizations, customer support, package
  management, release cycles etc
• Common linux directory structure

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Starting off with Linux ...

• /etc configuration files, init scripts ...
• /home user home directories
• /usr sources, include files, shared files,
  libraries, local installations ...
• /lib - libraries
• /bin - executables
• /opt optional software
• /boot kernel image
• /proc kernel data structures

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Basic commands

• Bash shell most popular history, command line
  editing, rich customization
• Startup .bashrc, .cshrc
• Environment variables PATH, PS1, SHELL,
  TERM, EDITOR, HOME

• Basic commands
• cd ls pwd
• echo export
• alias
• cat head tail touch
• date cal
• whoami id finger
• man apropos info
• top ps kill
• find locate
• grep more less ...

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Bash Shell Tricks

• Moving around
• ctrl-a ctrl-e alt-b alt-f
• Letter case
• alt-u alt-l alt-c
• !!, !1, !2, !x
• History ctrl -r
• reset
• edit mode
• prompt customization
• Escape character
• ctrl-v

• Delete words
• ctrl-w ctrl-u
• Kill rings ctrl-y alt-y
• Clear ctrl-l

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Pipes, Redirection, Indirection

• Everything is a file
• String together a bunch of simple commands to
  achieve a complicated task
• cmd1 cmd2 ....
• cmd1 gt some_file
• cmd1 lt input_file gt output_file
• append command gtgt output_file
• tee
• stdin 0, stdout 1 , stderr 2
• /dev/null, /dev/dsp ....

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Process management

• An interactive tool to observe load, mem usage,
  cpu usage, user, command executed, send signals,
  process state
• Can you 'top' this ?
• ps show processes on a machine, output format
  specifier
• Foreground, background processes
• Be 'nice' to your sysadmin else she'll 'kill' you
  
• Jobs 1, 2 ...
• Exit values of a process ?

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Remote login, Finding files, finding help ...

• Logging in with ssh
• Exporting X server
• Password less login with ssh-agent
• scp

• Find search files, directories etc
• Locate Faster, update regularly

• man
• apropos
• info
• Net forums, mailing lists
• RTFM

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Compress, Backup, cron

• Save disk space
• Compress using gzip, bzip2, zip
• Uncompress gunzip, bunzip2, unzip
• Viewing zip files zcat, zmore
• Regularly backup your important files
• Cron to run commands at regular intervals
• Man crontab

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Progrmming Environment

• Languages supported C, C, Fortran ??
• Debugger gdb
• compile with -g option
• Breakpoints, frames, watch, conditional
  breakpoints
• Makefile
• Example
• Editors vi , emacs
• Code browsers cscope, etags, ctags, sourcenav
• Configuration management RCS, CVS

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Installing software

• Compile from source
• Read the README
• Configure set the correct flags
• make and install
• Just install an RPM
• Dependency management is a problem
• New tools yum, apt, yast

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Text processing

• grep
• cut
• awk
• sort
• sed
• Lots of help available on the net
• Examples

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Vi, Emacs

• Vi one of the oldest editors
• Mode based editor Command mode, insert mode,
  colon mode, visual mode ...
• customized using /.exrc
• http//heather.cs.ucdavis.edu/matloff/ViIntro.htm
  l

• Emacs Extensible editor, better
• Most of the commands that appear in bash can be
  used in the emacs
• Customised using emacs-lisp. in /.emacs
• http//heather.cs.ucdavis.edu/matloff/Emacs.html

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Introduction to scripting

• Scripting in Bash , Perl, Python, csh etc etc
• Bash supports arrays, functions and anything that
  you can call from the shell

• Perl Prototyping, Extraction and Reporting
  Language
• Scalars, Lists, Hash Maps
• Rich set of libraries
• Language extensions

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Thank you

• GNU/Linux/Unix Has a 'steep' learning curve,
  but you have to learn it only once
• Use the Internet
• Read The Freakin' Manual

Exit