Harder, Better, Faster, Stronger

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Harder, Better, Faster, Stronger

• Basic tricks and tools to help improve the basic
  Linux user's experience
• By Cory Peterson

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Overview

• Improving Boot Time
• Bash Shortcuts and tricks
• Scripting
• Cronjobs

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Improving Boot Times

• Bootchart
• Readahead
• Profiling

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Bootchart

• Bootchart is a daemon that runs at startup and
  records timing for all processes that run on
  startup
• Using this tool, you can isolate which processes
  are taking the most time, and help to streamline
  the boot process

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Beginning Boot
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After Profiling and Tweaks
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After Editing rc.sysinit
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Boot Times

• Fastest way to decrease boot times is to turn off
  services at startup (sysV-rc-conf for ubuntu,
  system-config-services for fedora)
• Make sure readahead is running and do a profile
  on boot (must be redone after every new kernel)
  by adding profile to the end of the grub boot
  parameters

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Editing rc.sysinit

• Caution! You can render the system unbootable if
  you screw this file up, so keep a live cd handy
  and backup the file before you start
• Go through the file and find items that you may
  not be using, such as LVM and RAID. Comment out
  the unnecessary issues and then try booting again

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Parallel Daemons

• As Zach stated on the mailing list, another way
  to reduce boot time is to initiate parallel
  daemon startup. Adding '' to the end of 'i
  start' may seem like a good idea, but it ignores
  process dependencies and can make hardware not
  respond correctly
• The correct way involves 'make' and a lot more
  work (i won't be covering this section, maybe
  later on the mailing list)

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Filesystem Checks

• One other sticking point that may cause longer
  boot times is the periodic filesystem checks
• You can make these less frequent by using the
  tool 'tune2fs'
• This tool allows you to specify the boot times
  between checks

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Command Line Tricks

• First we'll start out with some basic tricks in
  case people don't know them
• Tab autocompletion, reusing previous commands
• One helpful tool is input/output redirection
• Using lt and gt you can redirect the input and
  output of any command.

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Examples

• lspci gt pci_list.txt causes the output of the
  lspci command to be written to a file named
  pci_list.txt
• You can also do multiple input redirection, such
  as combining two files to output into one
• cat lt(cat file1.txt) lt(cat file2.txt) gt
  combined.txt

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Combining Multiple Commands

• You can also specify multiple items in commands,
  take for instance removing 3 folders. You could
  use
• rm -rf /folder1
• rm -rf /folder2
• rm -rf /folder3
• Or just use
• rm -rf /folder1,folder2,folder3

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Aliases

• Another helpful trick is the use of aliases.
  Using aliases for commonly used commands can help
  reduce typing time.
• If you always want ls to output the full details
  of all files, typing ls -al is more typing than
  needed.
• alias ls'ls -al colorauto'
• You can still add other parameters to the aliased
  command

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Scripting

• Scripting can be a helpful tool for repetitive
  tasks
• The beginning of every script starts the same
  !/bin/bash
• You can use most of the command line calls and
  tricks in a script

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Basics

• You can use variables in a script
• VARvalue
• You can use expressions for these variables as
  well, such as if you want to name the file with
  the date, use
• OF/home/Cory/file-(date Ymd)
• Variables can be accessed using
• echo hi gt OF

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If Statements

• If statements are available in scripts, the basic
  syntax is as follows
• If foofoo then
• expression
• else
• expression
• fi

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For

• There are two kinds of for
• One is similar to 'for each' in java, other is
  like the normal 'for'
• For i in (ls) (use 'seq 1 10' instead for
  normal use)
• do
• commands
• done

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Functions

• You can also make functions in scripts
• Use the syntax
• function foo
• Commands
• echo 1
• You can use parameters by using the and
  numbers, in order of parameters

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Why Make Scripts

• There are many options on how to use a script
  once you've made it. You can alias a command to
  it, put it in a nautilus right click menu, run it
  on login, or even make it auto-execute with a
  cronjob.
• Aliasing has already been covered, so I will
  explain the other three

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Running on Login

• Copy the script into /.bash_profile, or else you
  can just tell it to run your script. This will
  execute it whenever you login
• You can also put it in /.bashrc, which will
  cause it to run whenever you open up a shell.

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Add to Nautilus Menu (Gnome)

• The easiest way is to just add the script into
  the /.gnome2/nautilus-scripts
• You can also install the nautilus-actions package
  and use it to create your own context-sensitive
  right-click shortcuts.

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Add to KDE Menu

• It is also very easy to add this script to your
  KDE desktop. It involves the creation of another
  file. For each script, you need to create a
  shortcut to the script, using the following
  information
• More information found at link 2 at end of
  presentation

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Shortcut Settings

• Desktop Entry
• EncodingUTF-8
• ServiceTypesapplication/x-shellsript
• ActionsActionName
• Desktop Action ActionName
• NameName Description
• Execcommand
• Iconicon name
• Move this file to /usr/share/apps/konqueror/servic
  emenus

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Add as a cronjob

• First you have to have a crontab set up.
• This is fairly easy if you don't have one, just
  make a file somewhere, probably home directory,
  and then use the command
• crontab filename
• This will then set the file as your current
  crontab.

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Adding Scripts to a Crontab

• Adding the script to run is fairly simple. Type
  'crontab -e' to edit it in vi
• The crontab has a 6 field syntax as follows
• 'min' 'h' 'd' 'mon' 'wd' 'command'
• The first 5 say when to run the command, means
  any value. Command is the command you want to run
  at the selected time

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Crontab Syntax

• You can also specify multiple times to run a
  command by using commas, for instance
• 0 0 1 1 /home/Cory/foo will run at 1200AM on
  Jan 1
• 0 12 1,15 /home/Cory/foo will run on the 1st
  and 15th of every month at noon.

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The End

• With These skills, it is very easy to improve the
  speed and usability of your Linux system
• Questions?

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Links

• 1 Linux Tips
• 2 KDE Script Shortcut
• 3 Parallel Daemons on Boot
• 4 Bash Scripting