Paj's Home: Programming: Unix

Unix

Introduction

Current content:

This section will be developed much further in the future. Planned content:

How an ISP works
How to run the best ever web hosting platform
General intro to sys-admining - how to be good at your job
How computers and operating systems work

Contributions, comments and requests always welcome.

My ideas for a Linux disto

Base as much as possible on a database (probably PostgreSQL as we need triggers). When a service is installed, it adds itself to the startup table, the log rotate table, etc. Use a database for /etc/passwd, .pid files, aliases, logging, etc.
Use python instead of bash for the startup scripts. Existing ones are too complicated for bash.
Startup scripts should have a dependency tree, rather than a numerical order.
Have something like RedHat's "service iptables save" that saves current network config. This means you can setup the network using ifconfig/route directly, then just save it. Or if you like you can edit the save file and restart it.
Definitily use a package manager, either .deb or .rpm

To realise this, you'd need modified software that followed the database model. need a database-driven cron, syslog, PAM module, xinetd, logrotate. Exim could do the SMTP. MyDNS for name lookups. Apache has lots of hooks, need a good config. Courier for IMAP, POP3.

Handy bash features

Ctrl-r	Reverse search through command history
Ctrl-o	Execute a command in the history, then go to next command in history
Alt-#	Cancels current command, but leaves it in history
Alt-f, Alt-b	Forward / backward a word
Alt-d, Alt-Backspace	Forward / backward delete a word
Ctrl-a, Ctrl-e	Beginning / end of line
echo $((17+15))	A handy calculator
echo prefix_{two,endings}	Gives you: prefix_two prefix_endings

Tape Backups

Some tips:

Label the tapes, but don't label the boxes. This way a tape can never get into the wrong box.
Use an external drive. If you computer is stolen, this is much less likely to go with it.
Have the software eject the tape at the end, but only if the backup is successful. This way admins know if there were any problems without having to check the logs.

And please, learn how to restore from the backups. There may be some gotchas which you really don't want to hit in an emergency.