LinuxCBT_EL-5_Edition_Notes.txt

###LinuxCBT EL-5 Edition###
Focuses on: RedHat Enterprise v5x
Successor to LinuxCBT EL-4 Edition, which succeeds LinuxCBT Classic Edition

Features:
 1. 2.6x kernel (2.6.18)
  a. 'uname -a' returns OS/Kernel information
Note: 'uname -a' returns the following useful info:
 1. OS - Linux
 2. Fully Qualified Domain Name (FQDN)
 3. Kernel version - 2.6.18...
  a. 2.6 = major version
  b. .18 = minor version
  c. anything else after the minor version indicates that the kernel was patched by the distributor
 4. Date and time that the kernel was compiled

 2. Supports multiple versions:
  a. Basic - Red Hat Enterprise Linux Server
   a1. supports 2 physical (Socket) CPUs
   a2. Up to 4 virtual guests

  b. Advanced Platform 
   b1. supports unlimited physical CPUs
   b2. supports unlimited virtual guests

Note: Virtualization limits pertain to the virtualization technology included with Red Hat Enterprise Linux. NOT third-party software (VMWare)


 3. Supports the following platforms:
  a. Intel 32/64-bits
  b. AMD 32/64-bits
  c. IBM - POWER and z-series, S/390

Note: Memory limitation is based on hardware


Note: Common uses of the various versions of RHEL
 1. RHEL Basic Version
  a. File & Print
  b. Web server
  c. Infrastructure server (DHCP, DNS, Proxy, etc.)

 2. RHEL Advanced Version
  a. Application server (Apache Tomcat, JBOSS, Weblogic, WebSphere, etc.)
  b. Database server (MySQL, PostgreSQL, Oracle, Ingres, etc.)
  c. Clustering


###Kickstart Configurator###

Features:
 1. Hands-free, automated installation
 2. Scripted installation
 3. Script can be used on multiple systems

Note: 'system-config-kickstart' is NOT installed by default

Steps:
 1. Open previously created 'anaconda-ks.cfg' file and modify
 2. Define partitions accordingly
 3. Confirm settings
 4. Publish the 'ks.cfg' file to HTTP server
 5. Install server using the following at the main menu:
  'linux ks=http://192.168.75.100/ks.cfg'

Note: The following can be used to boot a kickstart installation:
 1. boot.iso CD-ROM
 2. First CD-ROM of the RH5 installation set
 3. The DVD-ROM of the RH5 installation set
 4. USB Pen/Stick - diskboot.img (use dd)



###FTP INSTALLATION###

Steps:
 1. Create FTP user account on FTP server
  a. 'useradd -s /bin/false -d /srv/wwwlinuxcbt.com linuxinstall'
  b. 'passwd linuxinstall'
 2. Confirm FTP connectivity as the user 'linuxinstall'

 3. Reboot server with 'boot.iso' CD and type 'linux askmethod'

###BASIC LINUX COMMANDS###

1. tty - reveals the current terminal
2. whoami - reveals the currently logged-in user
3. which - reveals where in the search path a program is located
4. echo - prints to the screen
 a. echo $PATH - dumps the current path to STDOUT
 b. echo $PWD - dumps ths contents of the $PWD variable
 c. echo $OLDPWD - dumps the most recently visited directory

5. set - prints and optionally sets shell variables
6. clear - clears the screen or terminal
7. reset - resets the screen buffer
8. history - reveals your command history
 a. !690 - executes the 690th command in our history
 b. command history is maintained on a per-user basis via: 
  ~/.bash_history
~ = users's $HOME directory in the BASH shell
9. pwd - prints the working directory
10. cd - changes directory to desired directory
 a. 'cd ' with no options changes to the $HOME directory
 b. 'cd ~' changes to the $HOME directory
 c. 'cd /' changes to the root of the file system
 d. 'cd Desktop/' changes us to the relative directory 'Desktop'
 e. 'cd ..' changes us one-level up in the directory tree
 f. 'cd ../..' changes us two-levels up in the directory tree

11. Arrow keys (up and down) navigates through your command history
12. BASH supports tab completion: 
 a. type unique characters in the command and press 'Tab' key
13. You can copy and paste in GNOME terminal windows using:
  a. left button to block
  b. right button to paste OR Ctrl-Shift-v to paste

14. ls - lists files and directories
 a. ls / - lists the contents of the '/' mount point
 b. ls -l - lists the contents of a directory in long format:
 Includes: permissions, links, ownership, size, date, name
 c. ls -ld /etc - lists properties of the directory '/etc', NOT the contents of '/etc'
 d. ls -ltr - sorts chronologically from older to newer (bottom)
 e. ls --help - returns possible usage information
 f. ls -a - reveals hidden files. e.g. '.bash_history'
Note: files/directories prefixed with '.' are hidden. e.g. '.bash_history'

15. cat - catenates files
 a. cat 123.txt - dumps the contents of '123.txt' to STDOUT
 b. cat 123.txt 456.txt dumps both files to STDOUT
 c. cat 123.txt 456.txt > 123456.txt - creates new catenated file

16. mkdir - creates a new directory
 a. mkdir testRH5 - creates a 'testRH5' directory

17. cp - copies files
 a. cp 123.txt testRH5/
By default, 'cp' does NOT preserve the original modification time

 b. cp -v 456.txt testRH5/

18. mv - moves files
 a. mv 123456.txt testRH5/ - moves the file, preserving timestamp

19. rm - removes files/directories
 a. rm 123.txt
 b. rm -rf 456.txt - removes recursively and enforces

20. touch - creates blank file/updates timestamp
 a. touch test.txt - will create a zero-byte file, if it doesn't exist
 b. touch 123456.txt - will update the timestamp
 c. touch -t 200801091530 123456.txt - changes timestamp

21. stat - reveals statistics of files
 a. stat 123456.txt - reveals full attributes of the file

22. find - finds files using search patterns
 a. find / -name 'fstab'
Note: 'find' can search for fields returned by the 'stat' command

23. alias - returns/sets aliases for commands
 a. alias - dumps current aliases
 b. alias copy='cp -v'


###Linux Redirection & Pipes###
Features:
 1. Ability to control input and output

Input redirection '<':
 1. cat < 123.txt
Note: Use input redirection when program does NOT default to file as input

Output redirection '>':
 1. cat 123.txt > onetwothree.txt
Note: Default nature is to:
 1. Clobber the target file
 2. Populate with information from input stream


Append redirection '>>':
 1. cat 123.txt >> numbers.txt - creates 'numbers.txt' if it doesn't exist, or appends if it does

 2. cat 456.txt >> numbers.txt


Pipes '|':
Features: Connects the output stream of one command to the input stream of a subsequent command

 1. cat 123.txt | sort
 2. cat 456.txt 123.txt | sort
 3. cat 456.txt 123.txt | sort | grep 3


###Command Chaining###
Features:
 1. Permits the execution of multiple commands in sequence
 2. Also permits execution based on the success or failure of a previous command

 1. cat 123.txt ; ls -l - this runs first command, then second command without regards for exit status of the first command

 2. cat 123.txt && ls -l - this runs second command, if first command is successful
 3. cat 1234.txt && ls -l

 4. cat 123.txt || ls -l - this runs second command, if first command fails


24. more|less - paginators, which display text one-page @ a time
 1. more /etc/fstab
 2. less 1thousand.txt

25. seq - echoes a sequence of numbers
 a. seq 1000 > 1thousand.txt - creates a file with numbers 1-1000

26. su - switches users
 a. su - with no options attempts to log in as 'root'

27. head - displays opening lines of text files
 a. head /var/log/messages

28. tail - displays the closing lines of text files
 a. tail /var/log/messages

29. wc - counts words and optionally lines of text files
 a. wc -l /var/log/messages
 b. wc -l 123.txt

30. file - determines file type
 a. file /var/log/messages


###Tar, Gzip, Bzip2, Zip###
Features:
 1. Compression utilities (gzip, bzip2, zip)
 2. File rollers (the ability to represent many files as one)


Gzip:
Includes:
 1. gzip - compresses/decompresses files
 2. gunzip - decompresses gzip files

Tasks:
 1. compress '1million.txt' file using gzip
  a. gzip -c 1million.txt > 1million.txt.gz

Note: gzip auto-dumps to STDOUT, by default

  b. gzip -l 1million.txt.gz - returns status information
  c. gunzip 1million.txt.gz - dumps to file, and removes compressed version
  d. gzip -d 1million.txt.gz
  e. zcat 1million.txt.gz - dumps the contents to STDOUT
  f. less 1million.txt.gzip - dumps the contents of gzip files to STDOUT


Bzip2:

 1. bzip2 -c 1million.txt > 1million.txt.bz2

Note: Bzip2 tends to outperform gzip on larger files
 2. bunzip2 1million.txt.bz2
 3. bzip2 -d 1million.txt.bz2
 4. bzcat 1million.txt.bz2 - dumps contents to STDOUT
 5. less 1million.txt.bz2 - also dumps the contents to STDOUT


Zip & unzip:
 1. zip filename.zip path/ - general usage
 2. zip 1million.txt.zip 1million.txt
Note: zip differs slight from gzip and bzip2 in that the destination file (resultant zip file) is specified before the source
 3. unzip 1million.txt.zip


Tar & Gzip/Bzip2:

 1. tar -cvf filename.tar path/ - creates a non-compressed archive
 2. tar -cvf 1million.txt.tar 1million.txt
Note: tar, requires a small overhead for itself in each file

 3. tar -czvf 1million.txt.tar.gz 1million.txt - creates, tar/gzip document
 4. tar -cjvf 1million.txt.tar.bz2 1million.txt - creates, tar/bzip2 document
 5. tar -tzvf

 6. tar -cjvf 1million.txt.tar.bz2 1million.txt testRH5/- creates, tar/bzip2 document for the text file and 'testRH5' directory tree



###GREP###
Features:
 1. The ability to parse lines based on text and/or RegExes
 2. Post-processor
 3. Searches case-sensitively, by default
 4. Searches for the text anywhere on the line


1. grep 'linux' grep1.txt
2. grep -i 'linux' grep1.txt - case-insensitive search
3. grep '^linux' grep1.txt - us...