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Lab 8 Overview
Apache Web Server
Linux Tricks
SCRIPTS
Scripts
Small programs to help the maintaining
and configuring of an operating system
Executed by the shell
Syntax dependent on shell
Typical use:
Create a bunch of new users
Configure a service
De facto extension:
.sh
Change terminal color
Contents of a file named changecolor:
#!/bin/bash
# script to turn the screen blue
setterm -background blue
echo It is a blue day
Line 1: specifies which shell should be used to interpret the commands in the script.
Line 2: is a comment (has no effect when the script is executed).
Line 3: sets the background colour.
Line 4: displays a message.
Assuming the file is executable: e.g. the permissions is at least --x --- --- by the owner
To execute if it is in the PWD (current directory):
./changecolor
If in another directory use the fully qualified name:
/home/mydir/utils/changecolor
Simple Menu Script
These can be as complex as needed with conditional and loop
controls (among many other things)
#!/bin/bash
OPTIONS="Hello Quit"
select opt in $OPTIONS;
do
if [ "$opt" = "Quit" ]; then
echo done
exit
elif [ "$opt" = "Hello" ]; then
echo Hello World
else
clear
echo bad option
fi
done
Running Scripts Basics
 Make sure the first line is a directive of which shell to use (if needed)
 Starts with a shebang: #!
 For Debian it is the bash shell
 /bin/bash
 Make sure it is executable
 rwxr-xr– User can run, edit and view
 Group can run and view
 World can view
 chmod 754 script.sh
 If the shell is in a directory defined in the PATH
 echo $PATH
 Will show the directories
 type: filename
 If it is not in PATH but it is in the PWD
 type: ./filename
 If not in PATH and not in the PWD
 type full filename starting with the root:
/home/ajkombol/Desktop/script.sh
Script one: netconfig.sh
Desired action:
• stop the NIC
• open the interfaces file to edit
• restart the NIC
• add two nameservers to the resolve.conf file
The script:
#!/bin/bash
NETCONFIGFILE=/etc/network/interfaces
RESOLVECONF=/etc/resolv.conf
ifdown $1
vi $NETCONFIGFILE
#vi $RESOLVECONF
ifup $1
echo 'nameserver 172.16.1.254' >> $RESOLVECONF
echo 'nameserver 172.16.1.250' >> $RESOLVECONF
To execute the script:
myprompt#./netconfig.sh eth0
Quick script intro
Parameters passed to a script are denoted
by $1, $2, $3, …
$1 is the first parameter, $2 is the second, etc.
$# is the number of parameters passed
Variables are case sensitive
Environment variables
Used by the system in general
Are UPPER case by convention
Quick script intro (cont.)
 Conditionals are done by an if…elif…else…fi structure
 if and elif are followed by a command that evaluates to true or
false
 elif and else are optional
 elif can be repeated
 Only one else may be used, if needed
 if is closed with the fi statement
 To stop in the middle of a script use exit n
 n = 0 is a normal exit
• If n is not specified it is assumed 0
 n = 1 is an error exit
• Actually any non 0 value is an error
 If a value needs to be checked the test command is used
 Numbers use conditionals
• e.g. –gt, -lt, and –eq
 greater than, less than, equal
• EX: test 1 –gt 2
 Strings use operators
• e.g. = or !=
 equal and not equal
• EX: test $1 = "opt1"
 There are other comparisons that can be done, check the
internet
Script two: go
Desired action:
• stop the NIC,
• check which option
• copy the proper template to interfaces,
• restart the NIC
Note: eth0 is assumed to be the NIC name
#!/bin/bash
IFILE=/etc/network/interfaces
ifdown eth0
if test $1 = "static" ; then
cp $IFILE.static $IFILE
echo "Static interfaces loaded!"
elif test $1 = "dhcp" ; then
cp $IFILE.dhcp $IFILE
echo "DHCP interfaces loaded!"
else
echo "Parameter must be static or dhcp"
fi
ifup eth0
To execute the script:
myprompt#./go static
…
myprompt#./go dhcp
Today's labs scripts summary
 Changing network configuration
 Script one – editing the interfaces file
 stop NIC
 edit interfaces
 add some additional routing information
 start NIC
 Script two – alternating interfaces templates
 Make two interfaces templates
 stop NIC
 Copy the desired template
 start NIC
 You may wish to keep these scripts
 Use netconfig.sh to edit the interfaces file
 After making appropriate changes
 Use go or go2 to switch between
 DHCP addresses
 Static addresses
Reminder
 ALWAYS make a backup copy of a configuration
file BEFORE editing it
Will allow the file to be restored
 If you mess it up
 If something else messes it up
Examples:
 cp interfaces interfaces.backup
 cp apache2.conf apache2.conf.orig
 Make a copy of a line to be changed in a file and
comment it out before changing the original
Example:
 # This is the original line
This is the changed line
Main Lab
APACHE
Apache Web Server
Main Goals
Install Apache
Configure basic system
Configure restrictions
Side goals
Installing packages on a Debian System
Reinforce VM environment
Reinforce use of vi editor
Apache Web Server Overview
 Install Apache on your Debian VM
 apt-get
 Backup: Synaptic Package Manager
 No credit for Synaptic install
 Check if installation worked
 Create new directories
 “Install” the web application
 Configure Apache to “find” the new “application”
 Copy Web page files into proper directories
 Hint: assume the Web application is being moved from a
different Web server to this machine
 Configure Apache for restrictions
 Allow directory access
 Deny directory access
 Browse the application from another machine
Misc. Notes
 Debian required for the Apache Server
 CentOS recommended for the browsing client
 Can be any OS with a browser
 Use ifconfig to identify your IP address
 Web files (.htm and pics) available on hades.lab
 Use browser to locate
 /apachelab
• e.g. lab302-web.hades.lab/classes/apachelab
 (172.16.1.250)
 In /public directory
 Also available
 ON website
 on thumbdrive
 You will need to figure out on your own where the images go
to be properly displayed
 All web pages except home have an image
 A subdirectory is involved!
IMPORTANT!!!!
This Debian VM must be working and saved!
Will be used as the basis for the DNS Lab!
Apache Overview
 “Open source” web server
 Default browser “root” directory
 NOT the same as the host’s root directory!
 Location:
 /var/www
 /var/www/htdocs
 Depends on distribution
 To access the web server:
 Use the IP address or host name
 Port 80
 Bonus:
 At end of lab add port to browse on port 8080
 Document results
Last minute notes:
 Check the links to
test1.html
test2.html
They should go to the ITIS2110 directory
 Watch the IP addresses of your VM
DHCP OK this lab
 Need to look up address for browsing
If address was assigned
 Be sure does not conflict with another machine
• Can use machine ID as subnet or host id
• Can use your subnet (see listing on post)
Apache Lab
Lab 20 pts