YOUR TECHNICAL MANUAL Basic Linux Commands Congratulations on choosing Linux as the Operating System for your business. 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 laptops/computers) 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 : mx2.mweb.co.zw Incoming Mail Server : mx3.mweb.co.zw Primary Domain Name Server : 188.8.131.52 Secondary Domain Name Server : 184.108.40.206 Internet Access Proxy Server : proxy.mweb.co.zw Port : 8000 Connection (Hunting) Numbers The numbers to use when dialing up to MWEB are as follows : Harare 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 Bulawayo 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 firstname.lastname@example.org. 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 twice. 3. Deleting a User type userdel -r username 4. Forcing a connection to MWEB type ping mweb.co.zw The modem will dial and once connected you will get the following text scrolling on your screen: 64 bytes from 220.127.116.11: icmp_seq=0 ttl=255 time=0.7 ms 64 bytes from 18.104.22.168: icmp_seq=1 ttl=255 time=0.6 ms 64 bytes from 22.214.171.124: icmp_seq=2 ttl=255 time=0.5 ms 64 bytes from 126.96.36.199: icmp_seq=3 ttl=255 time=0.5 ms 64 bytes from 188.8.131.52: 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 following; 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 limpopo.mweb.co.zw 25. You will get the text ‘Trying 184.108.40.206 Escape character is ..”appearing on your screen and once a line has appeared to the effect 220 limpopo.mweb.co.zw ESMTP Exim3.33 #1 Fri, 10 May 2002 10:59:03 +0200, type etrn your domainname.co.zw 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 running 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 running 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 email@example.com <mailto:firstname.lastname@example.org>.