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        Basic Linux Commands

Congratulations on choosing Linux as the Operating System for your

This is a short introductory leaflet to introduce you to Linux - if you are unfamiliar with it, describe
its advantages and a few basic administrative tasks you may need to undertake.

Linux is freeware, therefore no annual licensing fees are payable. Linux also allows you to have a
virtually unlimited number of users on your system. It is an extremely stable operating system
which can be administered remotely - therefore should you have a problem it is possible for our
technicians to log into your server remotely and troubleshoot without leaving MWEB, thus saving
you time and money. The main advantages of the Linux Operating System include:

           Multitasking (a technique for sharing a single processor between several
            independent jobs)
           Virtual Memory (allows repetitive, extended use of the computer's RAM for
            performance enhancement)
           Fast TCP/IP Drivers (for speedy communication)
           Shared Libraries (enable applications to share common code)
           Multi-user Capability (this means hundreds of people can use the computer at the
            same time, either over a network, the Internet, via computer terminals or on
           Protected Mode (allows programs to access physical memory, and protects stability
            of the system)

Basic Descriptions

Linux is a variant of UNIX thus although Linux now comes with varying graphical user interfaces
(GUI) it is primarily a command line driven operating system. This function enables greater
control over the computer but demands greater knowledge of the computer and the operating
system than a GUI.

The shell is a command interpreter that acts as an interface between the user and the operating
system. When you enter a command at a terminal, the shell interprets the command and tells the
operating system to execute the program you want. The shell can be used as a high level
programming language.

Basic Guidelines

Your server is set up to dial-on- demand which means it will automatically dial and connect to
MWEB should you want to connect to the Internet. It will also however connect to MWEB every
50 minutes (default setting which can be changed) during working hours to send and retrieve mail
to/from our servers.

Under normal circumstances the server will display the login prompt. Please note there is no
need to log in to the box unless you want to do some administrative work in which case you login
as root followed by the root password. If you have forgotten or lost the root password, check the
welcome letter or see below.
General Mail Settings

        Mail Spooling
Outgoing Mail Server                     :
Incoming Mail Server                     :
Primary Domain Name Server               :
Secondary Domain Name Server             :

        Internet Access

Proxy Server                             :
Port                                     :       8000

        Connection (Hunting) Numbers

The numbers to use when dialing up to MWEB are as follows :

        Southampton Life Centre          Pilot number 1          (04) 70908
                                         Pilot number 2          (04) 706222
                                         Pilot number 3          (04) 252525
        Robinson House                   Pilot number            (04) 777345
        Graniteside                      Pilot number            (04) 773040
        Highlands                        Pilot number            (04) 43704

        Zimdef House                     Pilot number 1          (09) 330001
                                         Pilot number 2          (09) 62005

        Mutare                           Pilot number            (020) 68037

Linux maintenance

1.   To add users
     At the root prompt [root@yourdomain/root]# type adduser username where username
          is the first part of the email address for the user as in

2.   Defining/ Changing a user password
     type passwd username
     You will be prompted to type in a new password in which case you just oblige. Often you
     will get a bad password message, which you can disregard. The password is entered

3.   Deleting a User
     type userdel -r username

4.   Forcing a connection to MWEB
     type ping
     The modem will dial and once connected you will get the following text
     scrolling on your screen:
         64 bytes from icmp_seq=0 ttl=255 time=0.7 ms
         64 bytes from icmp_seq=1 ttl=255 time=0.6 ms
         64 bytes from icmp_seq=2 ttl=255 time=0.5 ms
         64 bytes from icmp_seq=3 ttl=255 time=0.5 ms
         64 bytes from icmp_seq=4 ttl=255 time=0.5 ms

      This maybe halted by pressing the keys Control + C simultaneously. It is advisable to
      halt the process otherwise your server will remain connected to MWEB generating a huge
      phone bill.

5.    Rebooting Your Server
      type init 6 or shutdown -r now or simply reboot

6.    Shutting Down Your Server
      Although this should not be necessary, the commands are init 0 or shutdown -h now

7.    Power cuts/ Corrupt file system
      Improper shutdowns and power cuts can cause corruption and when the
      server comes up it may prompt for a file system check. It will ask you to enter the root
      password or press Control+D for normal start-up. Supply the root password then at the
      next prompt type fsck /dev/hdaX, where X is the corrupt partition. This partition can be
      identified by reading the text appearing above the prompt and is usually hda1 or
      hda3. For SCSI drives substitute the hdaX with sdaX.

8.    Users Mail
      Some users may have very large messages in their inboxes that they are failing to
      download (seen by machine hanging in process). To check this at the server,

      i. cd /var/spool/mail

      ii. mutt -f username

      You will be able to see the user's mail and manipulate (delete) it.

9.    Recovering root passwd.
      This applies when you have lost/forgotten the root passwd. To recover it do the
      Reboot server, when it displays LILO boot: type in linux 1 and press enter. This will
      boot the computer into single user mode. After going through the normal
      processes it will display the prompt bash#.
      Type in passwd password where password is the new password. Reboot the machine.
      You can now log in using the new password.

10. Checking Mail Queue
    At # prompt type mailq
    This will display your mail queue

11. Forcing Mail Through
    At # prompt type sendmail -q -v
    v is verbose option allowing you to actually see the mail going through and may be omitted.

12.    Manual Retrieval of Mail
      This shouldn’t be necessary but the procedure is: At # prompt type telnet 25. You will get the text
      Escape character is ..”appearing on your screen and once a line has appeared to the effect
      220 ESMTP Exim3.33 #1 Fri, 10 May 2002 10:59:03 +0200, type
      etrn your
      You should get a line which says 250OK on your screen. You can then type quit

13.    To check whether services are still running
      a) to check whether sendmail is running, you type at the prompt
      # service sendmail status You should something like this in response, # sendmail PID is

      b) to check whether squid is running you type at the prompt
      # service squid status You should get something like this in response, # squid PID is

14.   Stopping and starting services
     In case you have problems with your computer browsing or receiving mail and you are sure
you are connected to MWEB, it is advisable that you restart the services that control these
daemons. To do thus at the prompt

       a)   for sendmail you type # service sendmail restart
       b)   for squid you type # service squid restart

The guidelines given are for first level support. Should you require further assistance please
contact our MWEB Business Solutions Frontline Technicians on (04) 25 33 55 , or send an email
to <>.