1. Day 8 Exporting Displays Cronjobs Mount

2. Chapter 5 Chapter 5 talks about X windows. –You should read the chapter. –However, you do not need to pay particular concern to the different window managers, and desktop environments. Just be aware that they exist. –They don’t pay nearly enough attention to exporting displays

3. Windows In windows you can control a remote machine with special software –PCAnywhere –Citrix Winframe –Windows Terminal Service –VNC All of these are copies of the UNIX ability to export your display.

4. Running graphical applications remotely On the machine which you wish to have the application show up, you must grant permission to accept incoming X requests: –xhosts +10.1.1.1 Would grant the machine 10.1.1.1 permission to export applications to you. –xhosts + Would grant ALL machines to export applications to you

5. Sending the application First you must set the DISPLAY environment variable: –export DISPLAY=“10.1.1.1:0.0” Would set your DISPLAY variable to the machine 10.1.1.1 on desktop 0.0 Then you will start the application you want: –xcalc & Notice it doesn’t show up on YOUR screen, but on the other persons.

6. Cron Jobs This is the way to schedule things in Unix. –crontab -e will allow you to edit you jobs –crontab -l will show you all jobs which you currently have scheduled –crontab -r will remove all your jobs. Each user can have their own set of jobs to run. Any output from the job will be mailed to you.

7. Crontab entry format Format is as follows: –m h d m w Program m - Minutes past the hour to run the job –* Every Minute –0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 ( Every 5 Minutes) h - Hours to run the job d - Date of the month to run –1 would mean to run it on the first of each month m - Month –0 is January, 1 is February w - weekday –0 is Sunday, 1 is Monday etc.

8. Unix File System During install we setup 3 partitions. –/ –/swap –/usr

9. Managing Mount Points Each partition must be mounted into the file system separately. We must make a mapping from /dev/had7 to /usr A mount point is how you specify where the device should appear in the current file system. –The place you mount the new partition must be a directory in the file system. Mounting a device is only good until you reboot. –To make it permanent, you must edit /etc/fstab

10. Adding new drive. Install the drive –fdisk /dev/hdb –mke2fs /dev/hdb1 –Now make a directory in your existing file system, and mount the new guy on there. mkdir /mnt/newdrive mount /dev/hdb1 /mnt/newdrive –Add it to /etc/fstab to make it happen automatically on bootup.

11. Un-mounting Make sure you are in some directory other than the one you wish to unmount. –Then type: –umount

12. File system management. To see how much space is in use on your partitions: –df

13. Accessing windows files. At the moment we have 2 different operating systems loaded on our laptop –Windows –Linux In linux wouldn’t it be nice to be able to access your windows files –mkdir /windows –mount /dev/hda1 /windows However you would have to do this each time you log in. –To automate, edit /etc/fstab.

14. Being a System Administrator Typically you will do the following tasks: –Run system backups –Restore files when uses accidentally delete them –Add/Remove users –Plan/Implement hardware/software upgrades Patches –Security –New feature –Do everything possible to ensure max uptime

15. Be Prepared The biggest roll of a system administrator is to be prepared for anything: –Fire –Natural Disaster (Hurricane, Tornado, Lightning) –Hardware Failure –Upgrades

16. Each place is different Some companies can stand to have some downtime every once in a while, others can’t. –Be sure to get a clear gauge of what is required when you are hired. 100% uptime 99% uptime Find out if/when you can have scheduled downtime.

17. Backup Backup Backup A good backup scheme will usually save you –Don’t rely on multiple hard drives to backup. –Make sure you are making tape/optical/cdrom backups –Make sure you are taking some of them offsite.