Linux. 3

Linux Install (Redhat 7.2) 3

Shutdown. 4

Turn on Services. 4

Login Log. 4

File Search Tool 4

File Size. 5

Directory Size. 5

Disk Usage/Free Space. 5

File Search Using locate. 5

Screen Capture Tool 5

Printer Setup using print server box. 5

Printing to non-default printer 7

Start/Stop/Restart Print Service (LPD) 7

Network Monitor 7

Package Manager 7

IP Lookup tools. 7

Compare Files. 8

Current Path. 8

Change File Time. 8

Various System Status Programs. 8

Fixing Ownership and Groups. 8

Create User Accounts via command line. 8

Passwords. 9

Disable Password Aging. 9

Disabling Root Login. 9

Pico w/o word wrap. 10

Change Gnome Terminal to Other user account 10

Backing up Server 10

Partial Backup (By directory Name) 10

Restore Server 10

List Files in TAR.. 11

Automatic Backup. 11

Adding a Hard Drive. 12

Apache Notes. 13

Apache HTML Directory. 13

Set up user web space. 14

Web Statistics. 14

Password Protecting Websites. 14

Start/Stop/Restart commands. 15

“Page Not Found” on file uploads via php scripts. 15

C Notes. 15

Known Differences between gcc and cc code. 15

To Run Compiled Code. 16

Compiling code that uses #include <asm/io.h>. 16

Compiling code that uses math.h library. 16

IO Port Programming. 16

Getting IO Port Programs to run under user accounts. 16

PHP Notes. 17

Ctime. 17

MySQL. 17

Getting Started. 17

Backing up MySql 17



Linux Install (Redhat 7.2)

{This is how MY machine is configured. It might not work the same way for you}


Boot from CD

At prompt






Model | layout | Deadkeys



2 button PS/2




Installation Type






Auto Partition




Disk Setup


Boot Loader




Allow Incoming: SSH, WWW, FTP


Language Support


Time Zone

Select Chicago (Central)


Root password

Type in password two times



Default AND:





Video Card


About to Install


Long Wait

Create Boot disk





Graphics Config


True Color




On first boot it will “FIND NEW HARDWARE” set up the Ethernet connection but ignore the sound card.


Be aware when it continues that when it hits eth0 it will take a while (making you think it locked up)……DO NOT reboot the machine, wait it out.


When the computer comes up, log in and go to the Service Configuration program and turn on HTTPD and turn off LPD.



shutdown –h now


Turn on Services

To turn on a service (ie httpd) use the following program in Gnome:

Programs | System | Service Configuration


Login Log



To show the last login for each user (this is a program not a text log):



File Search Tool

Use the following program in Gnome:

Programs | utilities | Gnome Search tool



File Size

To put output of ll, ls, df, du in human readable form, use the –h flag.


-h, --human-readable

                          print sizes in human readable format (e.g., 1K 234M 2G)


Directory Size

Use the following command to obtain the size of a directory or group of directories:


            du –hc dir


the –h puts the output in human readable format (see above) and the –c gives you a total (useful if you want the total of a tree)


Disk Usage/Free Space

Use the following command to obtain the usage of all mounted disks:


            df -h

File Search Using locate

To set up locate first do a: locate –u (this sets up the index file)

Then to search do: locate search_string

Screen Capture Tool

Use the following program in Gnome:

Applets | utilities | screen shooter


Printer Setup using print server box

To set up printer, use the following Gnome program:

Programs | system | Printer Configuration


1) Opening screen

Hit next

2) Setup the print Queue name and type

For Queue Name I used




For Queue Type use unix Printer

3) Configure a Unix Print Queue

For Server use the current printer IP as defined by the DHCP server


For Queue use:




as per SOL print server connections

4) Select a Print Driver

Self explanatory

5) Finish


Shows the configuration as set.

  • Change printer configuration for ‘Floyd-Steinberg Gray’ on the HP500c (or it will ask you to change the print cartridge)
  • Change printer configuration for normal quality on the HP1120C (it printed junk in presentation mode)


Two known problems with this setup procedure:

  1. In step 3, the IP changes when the print server resets and requests and IP from the DHCP so this configuration will need to be updated when that occurs.
  2. This allows all users to print, including remote users. I know that /etc/lpd.perms needs to be configured so that only requests from the local (192.168.*.*) will print all other requests are rejected, but so far every time I tried to modify the file it will not allow any print job.


Printing to non-default printer

lp –d printer_name filename


Where printer_name is the name used in step 2 of ‘Printer setup using print server box


Start/Stop/Restart Print Service (LPD)


/etc/init.d/lpd start|stop|restart


Network Monitor

Use the following program in Gnome:

Programs | internet | RH Network Monitor


Will give you a window like this:


Eth0 -> Ethernet card

Loopback  ->


Red (Top graph) -> Transmit

Green (Bottom graph) -> Receive


Package Manager

Use the following program in Gnome:

Programs | System | GnoRPM


Similar to windows “Add Programs”


IP Lookup tools


dig <ip-address>

host <ip-address>


Compare Files

Use the diff command:


diff [options] from-file to-file


Current Path



Change File Time

Use the “touch” command to change the file modify time by using:


Touch –w –t [CC]YYMMDDhh[.ss]                         [optional]


Various System Status Programs

ps –aux


top     [^C to end]


Fixing Ownership and Groups

When transferring files to user accounts when logged in as root, the file will be owned by root and in the root group. To change it to allow the user to modify these files type:


chown –R ownername *; chgrp –R groupname *


NOTE: the –R means that all files in the current directory and ALL SUB DIRECTORIES will be changed to the new owner and group


Create User Accounts via command line

To create a user account from a shell prompt:

1. At the shell prompt, log in as root.

2. Type useradd followed by a space and the username for the new account at the command line and press [Enter].

3. Now type passwd followed by a space and the username again.

4. The shell prompt should display New UNIX password. This is asking you to type the password for the new account.

5. Type the password again for confirmation.


[above from: ]



To give a user ROOT permissions:


Open the file /etc/passwd


The format of each line is as follows:


Name:Password: UserID(UID):PrincipleGroup(GID):Gecos: HomeDirectory:Shell


Change the uid and gid of the user to 0


Disable Password Aging

passwd –x –1 username

Disabling Root Login


1)     SSH into your server as 'admin' and gain root access by

su -

2) Copy and paste this line to edit the file

pico -w /etc/ssh/sshd_config

3) Find the line

#Protocol 2, 1

4) Uncomment it and change it to look like

Protocol 2

5) Next, find the line

#PermitRootLogin yes

6)Uncomment it and make it look like

PermitRootLogin no

7) Save the file

ctrl 'x' then 'y' then enter

8) Restart SSH


Above from:


Pico w/o word wrap

To turn off pico word wrap start pico with

pico –w


Change Gnome Terminal to Other user account




su username             (default username is root)


(su does not stand for Super User, it stands for Substitute User)


Backing up Server


To backup the server, I created a script that saves the most pertinent directories. The script is as follows:



tar -zcvpf backup-`date '+%d-%B-%Y'`.tar.gz /root /etc /home /var/www


this will create a file named “backup-dd-MONTH-yyyy.tar.gz”. I saved the script as


Partial Backup (By directory Name)

Say you wanted to do a backup of /home directory and place all users with the beginning initials a-m in one tar file. Here is how you can do it:


find /home/[a-m]* –type f -print |tar –zcvf filename.tgz –T –


and yes you need the ending – (not sure why).


[a-m] is NOT case sensitive!

Restore Server


To restore using a backup created using the above script, be logged in as root and in the / directory. Use the following command:


tar –xvzf file_name_of_backup(including_full_path)


If you only want to restore a file or directory from the backup use the above line but add the directory or file to restore:


tar –xvzf file_name_of_backup(including_full_path) name_to_restore




tar –xvzf  /usr/backup/backup-05-July-2003.tar.gz home


will restore only the home directory and all sub directories of home (because –v is verbose)


List Files in TAR

tar –ztvf name_of_file

Automatic Backup

To automatically backup the system do the following:





find /usr/backup -name 'backup*.tar.gz' -mtime +28 -exec /bin/rm {} \;

tar -zcpf /usr/backup/backup-`date '+%d-%B-%Y'`.tar.gz /root /etc /home /var/www



0 21 * * 1 sh /usr/


This will run the script every Monday at 9pm and remove backup files older than 28 days.



The following was taken from


Creating a Crontab

What is Crontab?

Crontab is a program that allows users to create jobs that will run at a given time. Each individual user has their own crontab and the entire system has a crontab that can only be modified by those with root access. If you are adding a crontab for an individual user you must sign on as that user first. (ex. su userid)

The syntax of this file is very rigid. There are six fields to a file, each separated by a space. The first five fields specify exactly when the command is to be run; the sixth field is the command itself. The first five fields are:


minute hour day month weekday command

Minute - Minutes after the hour (0-59).
- 24-hour format (0-23).
Day - Day of the month (1-31).
- Month of the year (1-12).
- Day of the week. (0-6; the 0 refers to Sunday).

Asterisks (*) specify when commands are to be run in every instance of the value of the field. For instance, an asterisk in the Month field would mean that the command should be run every month. In addition, multiple events can be scheduled within a field by separating all instances with commas - with no space between.


crontab -e
Edits the current crontab or creates a new one. *

crontab -l
Lists the contents of the crontab file.

crontab -r
Removes the crontab file.

Creating a Crontab for use with AccessWatch

You must first sign on as the individual user you are adding the crontab for. Do not create crontab while you are signed on as "su" under root or you will change the root crontab. After you sign on as root su as individual user.

su userid (ex su nercols)

Change editor to Joe from VI:

export EDITOR

Create the crontab from the command line:

crontab -e

Insert the following lines and the save the file (Ctrl-kx):

30 23 * * * /home/userid/www/aw/ -d
45 23 * * * /home/userid/www/aw/

AccessWatch will run against the log files in their home directory every evening at 11:30 and then generate a report at 11:45 p.m..

Type man crontab for more detailed information. If you don't want to set up a crontab just run the by hand when you want a report.



Adding a Hard Drive

The following was taken from

Adding a Linux Hard Drive by Dirk Hart



More Articles


I was asked to configure a second IDE hard drive for a RedHat 7 Linux system.


I was at a loss as to how to describe this new drive to Linux and after half an hour I realized that the drive had been autodetected at the time of the last boot. A little research showed how IDE drives are named:


Primary Controller First Drive: /dev/hda

Primary Controller Second Drive: /dev/hdb

Secondary Controller First Drive: /dev/hdc

Secondary Controller Second Drive: /dev/hdd


Then fdisk was used to partition the drive: fdisk /dev/hdc. I seleted the old partitions and added a single linux partition, making sure the partition type was 83 (Linux).


When that was done I used mkfs to make a filesystem. Since there was just one partition it was named /dev/hdc1: mkfs /dev/hdc1.


I made a mount point: mkdir /usr0 and mounted the new filesystem: mount /dev/hdc1 /usr0. The filesystem can be unmounted using umount /usr0.


Lastly, I made an entry in /etc/fstab describing the new filesystem so it would be mounted automatically mounted at boot time. This was tested using mount all and observing that the new filesystem was indeed mounted.


I followed the above instructions, but it still failed to work correctly. I found I had to execute the following command:


tune2fs –j /dev/drive


After executing the command, the new drive worked correctly.

Apache Notes

Apache HTML Directory


Set up user web space


In the configuration file /etc/httpd/conf/httpd.conf


# The path to the end user account 'public_html' directory must be

# accessible to the webserver userid.  This usually means that ~userid

# must have permissions of 711, ~userid/public_html must have permissions

# of 755, and documents contained therein must be world-readable.

# Otherwise, the client will only receive a "403 Forbidden" message.


# See also:


<IfModule mod_userdir.c>

    UserDir public_html



The line UserDir tells what the directory under /~userid/ has to be named for access from the www.


Also note the permissions described in the comments. This is accomplished by:

chmod 711 ~userid

chmod 755 ~userid/public_html


Web Statistics

Web statistics are generated by a program called webalizer.

The configuration file is /etc/webalizer.conf


Incremental mode (/etc/webalizer.conf line 64 was activated)


Password Protecting Websites

(taken from,24330,3405624,00.html)


In the configuration file /etc/httpd/conf/httpd.conf add the following lines


<Directory "/home/*/public_html">

        AllowOverride AuthConfig



You must Restart Apache at this time.


Then create a file named .htaccess in the directory to protect (note that all sub directories are also protected).

The file should read:


AuthUserFile “/path of directory/.htpasswd"
AuthGroupFile /dev/null
AuthName "name to display"
AuthType Basic
require valid-user

Valid-user will allow anyone in the .htpasswd file (see below) to log in.

Now make the file world readable by:

chmod ugo+r .htaccess


Finally create the password file by:


htpasswd –c .htpasswd username


note: failed logins can be found in /etc/httpd/logs/error_log



To redirect a webpage, use the following META command. This will redirect in 5 seconds and take the user to html-redirect.html.


      CONTENT="5; URL=html-redirect.html">


Start/Stop/Restart commands


You can start, stop and restart the Apache Web server by using scripts created for this purpose in Red Hat Linux. Type in a shell prompt as root: /etc/rc.d/init.d/httpd  start to start the server. To stop or restart use the same script but replacing start with stop or restart. You must start the server as root, in order to run the server in port 80, as defined in httpd.conf.


Above taken from:

“Page Not Found” on file uploads via php scripts

Edit the /etc/httpd/conf.d/php.conf file. Modify the LimitRequestBody line (increase the number to the right to the max file size)

C Notes

Known Differences between gcc and cc code



Void main(void)





To Run Compiled Code

Type ‘./a.out’


Compiling code that uses #include <asm/io.h>

cc –O


Compiling code that uses math.h library

To compile code that uses the math.h library use


cc –lm


it seems you do not need an #include <math.h> statement in the header, but you do need to explicitly declare the function.


So if you want to use the pow function you would think you should do this:


#include <math.h>
#include <stdio.h>


But you need to do this:


#include <stdio.h>

double pow(double x, double y);


[compile with the cc –lm]


I discovered this when trying to use the pow function. It kept on generating a “Undefined reference to ‘pow’” error on compile.


Found website that said how to fix it (as described above)

IO Port Programming

See file IO-Port-Programming.txt


Getting IO Port Programs to run under user accounts


chmod +s filename


[you will be asked for the root password]

chown root filename




PHP Notes


Ctime is not the “file creation time” but the “status change time”



Getting Started

To start mysql: 


mysql –u username –p


Mysql will then ask for a password (use the password for username)


When you get the prompt type:


show databases;


This will get you a list of current databases.


Refer to:


Backing up MySql




Create a folder on your server to hold all of your backup files. For example: home/yoursite/html/backup.

Telnet into your server and move to the "backup" directory.

Execute the following command substituting the words in italics with your actual mysql username, password, and database name:

mysqldump -uUSERNAME -pPASSWORD DATABASENAME > backup.sql

At this point all of your mysql tables should be backed up into a file called "backup.sql" within the backup directory. You can store this file there, FTP it to your home computer, or FTP it to another server to restore the data there.


The only trick with restoring the data is that if the tables already exist in your mysql database, then the restore will not work. Thus, you need to delete or rename any tables that exist before the backup.

From telnet, move into the directory containing the "backup.sql" file and type:


This will recreate all of the tables and insert all of the data. Note that you can use this method to transport the data to a mysql database on another server.


To dump all databases use:


mysqldump –all-databases > backup.sql