Ubuntu Server Setup

Turn on Mod Rewrite

1. a2enmod rewrite 
2. restart apache server 
3. edit vhost file AllowOverride all

Shell Scripting

• Scripts must be chmod 755 so they can execute

• #!/bin/bash (add to the top of the shell script so it can use the bash shell to interpret the script, you can also add python or other shell programs)

• Postional Parameters: $0 ... $9 $@ to access all 0-9 // like in a loop

• Exit Status return Codes: Range from 0 to 255: 0 = success: Other than 0 = error condition: use man or info to find meanign of exit status

&bull, $? contains the return code of the previously executed command

ls /not/here
    echo "$?"
Another Code example


    HOST="google.com"
      ping -c 1 $HOST # -c 1 means it will send 1 ping
      if["$?" -eg "0"]
      then
          echo "$HOST reachable"
      else
          "$HOST unreachable"
      fi
&& and ||
-the second statement only executes if the first one was successfull
mkdir /tmp/bak && cp test.txt /tmp/bak/
-the second statement will execute only if the first one fails
cp test.txt /tmp/bak/ || cp test.txt /tmp
• chain multiple commands together using a ; (semicolon) cp test.txt /tmp/ ; cp test.txt /bak

File Operators (test)

-d FILE -true if is a directory
-e FILE True if file exists
-f FILE True if file exist and is a regular file
-r FILE True if file is readable by you
-s FILE True if file exists and is not empty
-w FILE True if file is writable by you
-x FILE True if file is executable by you
-z FILE True if string is empty
-n FILE True if string is not empty
String1=String2 true if strings are equal
String1 != string2 True if the strings are not equal
arg1 -eq arg2 equal
arg1 -ne arg2 not equal
arg1 -lt arg2 less than
arg1 -le arg2 less than or equal to
arg1 -gt arg2 greater than
arg1 -ge arg2 greater than or equal to
read -p "Prompt to dispaly" VarableName accepting user input

for loop to rename all jpg files with the date

  #!/bin/bash
  PICTURES=$(ls *.jpg)
  DATE=$ (date +%F)

  for PICTURES IN $PICTURES
      do
          echo "Renaming ${PICTURE} to ${DATE} - ${PICTURE}"
          mv $[PICTUE} ${DATE}-${PICTURE}
  done

  // Output
  renaming bear.jpg to 2015-03-06-bear.jpg

Adding exit commands to scripts

    #!/bin/bash
      HOST="google.com"
      ping -c 1 $HOST
      IF [ "$?" -ne"0" ]
      then
          echo "$HOST unrechale"
          exit 1
      fi
      exit 0

Creating a Function

function function-name() {# code goes here}
Calling a Function
function hello() {
    echo "hello:
    }
    hello (you don't need the () just call the name of the function)
    
** Positional Parameters and passing info to a funciton


    #!/bin/bash
  function hello(){
      echo "hello $1"

  }

  hello robert # robert is passed to the function hello
  #output is hello Robert
** Outputting miltple calls to a function


    #!/bin/bahs
      funciton hello() {
      for NAME in $@
      do
          echo "Hello $NAME"
      done
  }

  hello robert bob dan

  Output
  hello robert bob dan
Using Wildcards 
* -matches zero or more characters
*.txt
a*
a*.txt
? - matches exactly one character
?.txt
a?
a?.txt
[] character class - matches any of the characters included between the brackets. Matches exactly one character.
[aeiou]* exampld: ls -la [abge]*
ca[nt] matches:(it will match either the n or the t)
can, cat, candy, catch
[!] Matches any characters NOT included between the brackets. Matches exactly one character.
[!aeiou]* would match below bacause it does not start with any of those letters
baseball, cricket
Select a range
[a-g]* matches files that start with a,b,c,d,e,f,g
[3-6]* matches all files start with 3,4,5,6
Using predefined Character Classes
[[:alpha:]]
[[:alnum:]]
[[:digit:]]
[[:lower:]]
[[:upper:]]
[[:space:]]

#!/bin/bash
cd /var/www/bash
  # there's a space after the "if", space afer ! then a space after "[", space before "]"
if [ ! -d  /var/www/bash/text/ ]
then
     mkdir /var/www/bash/text
fi
for FILE in *.txt
do
     echo "Copying $FILE"
     cp $FILE /var/www/bash/text
done
Case Statements

Apache Commands

• List apache packages and versions
  • dpkg -l | grep apache

• shows version of ubnuntu
  • cat /etc/issue

• shows version of ubuntu
  • cat /etc/*-release

• give detail status of the service
  • apachectl status

• Gives info on where config file is located
  • apachectl -V
• Search the entire server for the file
  • find / | grep "apache2\.conf"
• Info for each line in the .conf File
  • http://httpd.apache.org/docs/current/mod/directives.html
• Displays Config Info about all Virtual Hosts
  • apachectl -t -D DUMP_VHOSTS
• Display All Modules form Apache
  • apachectl -t -D DUMP_MODULES
• Enable and Disable Modules
• Directory for Modules
  • /etc/apache2/modes-available and /etc/apache2/mods-enabled
  • a2enmod and a2dismod will enable of disable modules
• Find where the apache error log is located
  • grep -Ri ErrorLog /etc/apache2
• Watch Error log in realtime
  • tail -f error.log
• Tools to Analize log files
  • AWStats - awstats.sourceforge.net
• GoAccess - Terminal app
  • goaccess.prosoftcorp.com

Using SMTP to send email

apt-get install php-pear

pear install Mail

pear install Net_SMTP

restart apache

## you have to include this in your code.

require_once 'Mail.php';

## there is a lot more info you have to provide. do a search or pear mail

Giving Root Privileges to another Account

edit  /etc/sudoers.tmp

#User previlege specification

root  ALL=(ALL:ALL)ALL

#  copy the settings of the root and adapt it to your username

alex ALL=(ALL:ALL)ALL

Installing Node.js

sudo apt-get install python-software-properties

add-apt-repository ppa:chris-lea/node.js

 

apt-get update
apt-get install nodejs npm

Search Repositories

sudo apt-cache search python

will search the cached repo of all python

Changing Mac Address Linux

ifconfig wlan0 down

ifconfig wlan0 hw ether de:ad:be:ef:co:fe

ifconfig wlan0 up

ifconfig wlan0 | grep HWaddr

Repair Perl Locale Errors on Ubuntu

sudo apt-get install language-pack-en-base
sudo dpkg-reconfigure locales
if that dosent work then try this
export LANGUAGE=en_US.UTF-8
export LANG=en_US.UTF-8
export LC_ALL=en_US.UTF-8
locale-gen en_US.UTF-8
apt-get install locales
dpkg-reconfigure locales

Remove Old host keys from Known_hosts

 ssh-keygen -f "/root/.ssh/known_hosts" -R 192.168.20.133

 

Sync Time with ntp server

 Using the command line, you can use dpkg-reconfigure tzdata.

dpkg-reconfigure tzdata
 
Follow instructions
 
install ntp
 
sudo apt-get install ntp

Setting up a Cron Job

Using cron

 Use the personal crontab to setup your jobs

type

crontab -e  ** use the -e switch, do not edit the file directly 

Everthing is the same as below except the 6th space in the personal crontab is the field to execute as oposed to the user to run the job

example

* * * * * /backup/script.sh

as opposed to

* * * * * root /backup/script.sh

 

crontab -l - shows scheduled jobs

crontab -r  remove the current crontab file

 

In the /etc directory you will probably find some sub directories called 

'cron.hourly', 'cron.daily', 'cron.weekly' and 'cron.monthly'. If you place 

a script into one of those directories it will be run either hourly, daily, 

weekly or monthly, depending on the name of the directory. 


If you want more flexibility than this, you can edit a crontab (the name 

for cron's config files). The main config file is normally /etc/crontab.

On a default RedHat install, the crontab will look something like this:

 
root@pingu # cat /etc/crontab

SHELL=/bin/bash

PATH=/sbin:/bin:/usr/sbin:/usr/bin

MAILTO=root

HOME=/


# run-parts

01 * * * * root run-parts /etc/cron.hourly

02 4 * * * root run-parts /etc/cron.daily

22 4 * * 0 root run-parts /etc/cron.weekly

42 4 1 * * root run-parts /etc/cron.monthly

 
The first part is almost self explanatory; it sets the variables for cron.

SHELL is the 'shell' cron runs under. If unspecified, it will default to 

the entry in the /etc/passwd file.


PATH contains the directories which will be in the search path for cron 

e.g if you've got a program 'foo' in the directory /usr/cog/bin, it might 

be worth adding /usr/cog/bin to the path, as it will stop you having to use

the full path to 'foo' every time you want to call it.

 
MAILTO is who gets mailed the output of each command. If a command cron is 

running has output (e.g. status reports, or errors), cron will email the output 

to whoever is specified in this variable. If no one if specified, then the 

output will be mailed to the owner of the process that produced the output.


HOME is the home directory that is used for cron. If unspecified, it will 

default to the entry in the /etc/passwd file.

 

Now for the more complicated second part of a crontab file.

An entry in cron is made up of a series of fields, much like the /etc/passwd

file is, but in the crontab they are separated by a space. There are normally

seven fields in one entry. The fields are:

 
minute hour dom month dow user cmd

 
minuteThis controls what minute of the hour the command will run on,

and is between '0' and '59'

hourThis controls what hour the command will run on, and is specified in

         the 24 hour clock, values must be between 0 and 23 (0 is midnight)

domThis is the Day of Month, that you want the command run on, e.g. to

run a command on the 19th of each month, the dom would be 19.

monthThis is the month a specified command will run on, it may be specified

numerically (0-12), or as the name of the month (e.g. May)

dowThis is the Day of Week that you want a command to be run on, it can

also be numeric (0-7) or as the name of the day (e.g. sun).

userThis is the user who runs the command.

cmdThis is the command that you want run. This field may contain 

multiple words or spaces.

 

Fields

 .---------------- minute (0 - 59) 

 |  .------------- hour (0 - 23)

 |  |  .---------- day of month (1 - 31)

 |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ... 

 |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7)  OR sun,mon,tue,wed,thu,fri,sat 

 |  |  |  |  |

 *  *  *  *  *  

 

If you don't wish to specify a value for a field, just place a * in the 

field.

 

e.g.

01 * * * * root echo "This command is run at one min past every hour"

17 8 * * * root echo "This command is run daily at 8:17 am"

17 20 * * * root echo "This command is run daily at 8:17 pm"

00 4 * * 0 root echo "This command is run at 4 am every Sunday"

* 4 * * Sun root echo "So is this"

42 4 1 * * root echo "This command is run 4:42 am every 1st of the month"

01 * 19 07 * root echo "This command is run hourly on the 19th of July"

Notes:

Under dow 0 and 7 are both Sunday.

If both the dom and dow are specified, the command will be executed when

either of the events happen. 

e.g.

* 12 16 * Mon root cmd

Will run cmd at midday every Monday and every 16th, and will produce the 

same result as both of these entries put together would:

* 12 16 * * root cmd

* 12 * * Mon root cmd

Vixie Cron also accepts lists in the fields. Lists can be in the form, 1,2,3 

(meaning 1 and 2 and 3) or 1-3 (also meaning 1 and 2 and 3).

e.g.

59 11 * * 1,2,3,4,5 root backup.sh

Will run backup.sh at 11:59 Monday, Tuesday, Wednesday, Thursday and Friday,

as will:

59 11 * * 1-5 root backup.sh 

Cron also supports 'step' values.

A value of */2 in the dom field would mean the command runs every two days

and likewise, */5 in the hours field would mean the command runs every 

5 hours.

e.g. 

* 12 10-16/2 * * root backup.sh

is the same as:

* 12 10,12,14,16 * * root backup.sh

*/15 9-17 * * * root connection.test

Will run connection.test every 15 mins between the hours or 9am and 5pm

Lists can also be combined with each other, or with steps:

* 12 1-15,17,20-25 * * root cmd

Will run cmd every midday between the 1st and the 15th as well as the 20th 

and 25th (inclusive) and also on the 17th of every month.

* 12 10-16/2 * * root backup.sh

is the same as:

* 12 10,12,14,16 * * root backup.sh

When using the names of weekdays or months, it isn't case sensitive, but only

the first three letters should be used, e.g. Mon, sun or Mar, jul.

Comments are allowed in crontabs, but they must be preceded with a '#', and

must be on a line by them self.