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Web Application Deployment module A164
Services and Regular Jobs
Exercises, examples and other material relating to training module A164. This topic is presented on public courses Deploying LAMP - Linux, Apache, MySQL, Perl/PHP
, Linux Administration
, Deploying Java Applications on Linux / Unix
, Linux bootcamp
If you're running a server, you need to run daemon processes to provide services as they're requested. This module describes the startup and shutdown of daemons, and also how you can run regular jobs on your server to perform housekeeping and other tasks.
Related technical and longer articlesWindows clients to a Linux Server
|Articles and tips on this subject||updated|
|4487||Starting MySQL. ERROR! The server quit without updating PID file - how we fixed it.|
Our MySQL databases are backed up frequently, and I've arranged for our server to email me in the event of a failure. From our /bin/bash script which is run by crontab:
/usr/local/mysql/bin/mysqldump -ufgw -psummat -h127.0.0.1 fgw > /home/backups/$HOUR/fgw.sql
if [ "$?" -eq ...
|3792||Managing daemons from a terminal session|
If you want to manage a daemon on a Linux system, how do you do it?
• It's likely that you cannot log in directly as the dameon user, as the account will almost certainly not have a valid encoded password string, so every attempt to give a password (including just pressing "enter" when asked) would ...
|3791||The Kernel, Shells and Daemons. Greek Gods in computing|
The Greek Gods didn't like washing up or ironing. So they employed mortals to to it. Problem was that those mortals didn't last for ever, and sometimes went on strike over one thing and another. So The Gods did a deal with some of the current batch of mortals, and it went like this: "We will make you ...
Do we need to be on time? Well ... if I go to the station at 07:20 - that's a minute late for the 07:19 - there's a good chance that I'll have missed the train and have to make alternative arrangements to get where I need to be. Even a few seconds and "sorry, mate - I've already closed the doors; you'll ...
|3011||What are .pid files?|
wizard:run graham$ ls *.pid
When a process that needs to be contacted / alerted by other processes is started, it often records its process id (PID) into a ".pid file" ...
|1731||Apache httpd, MySQL, PHP - installation procedure|
If you're installing LAMP (Linux, Apache, MySQL, PHP), what do you do and in which order? Here's a summary of the procedure we followed on todays Apache httpd deployment course - in this case running (tailored) for a single company audience, and tailored for specfic needs.
(I've documented this and ...
|2182||What Linux run level am I in?|
Linux / Unix systems have a "run level" that they're in ...
0 - halted
1 - single user
2 - multiuser (client)
3 - full multiuser
5 - full multiuser with X windows running
6 - reboot
How do I find out what run level a system is in at the moment? - a question asked on today's Java course (OK - it was ...
|2145||Using the internet to remotely check for power failure at home (PHP)|
Do you have freezers and other electrical equipment at home and worry about whether they'll be all right while you're away on holiday? Do you have a broadband connection with a rarely changing IP address, and a web site that you host with a web space provider? Then you'll be able to set up a "heartbeat" ...
|1288||Linux run states, shell special commands, and directory structures|
Some useful notes from the board ...
Run states of Unix and Linux systems:
0 - Halted
1 - Single User
2 - Multiuser
3 - Full Multiuser (inc servers)
5 - Same + X Windows
6 - transient reboot
Install Order for LAMP
... then Apache httpd
... then MySQL
... then PHP.
PHP must be after MySQL ...
|907||Browser -> httpd -> Tomcat -> MySQL. Restarting.|
I've just completed a course covering the installation and configuration of Apache httpd, Apache Tomcat and MySQL. Complete with a demonstration that has the newly installed systems visited from various browsers, talking to httpd, which talks on to Tomcat, which talks on in turn to MySQL. The MySQL ...
|1903||daemons - what is running on my Linux server?|
Processes which (re)start when you start your computer and run until you halt it are known as services in the Microsoft world and daemons in the Linux and Unix world. As well as providing support for the operating system and user, the service / daemon mechanism is used on server computers to provide ...
|1765||Dialects of English and Unix|
English is spoken as a first language by over 300 million people, and by about five times that number if you include people who can speak it as a second or third language. But that doesn't mean that word and wording is going to be the same within different variants, let alone the subtleties and drifts, ...
|1733||memcached - overview, installation, example of use in PHP|
Let's say you have a large database on a busy server, and queries that are eating into your resources. Would you like to be able to speed things up?
It usually turns out that there are certain queries which are very frequent and which return the same results each time (or for a period of time) which ...
|1700||FTP server on Fedora Linux|
Using vsftpd ...
Turning on manually / for current boot
1. Log is as root
2. cd /etc/init.d
3. ./vsftpd start
[trainee@melksham ~]$ su -
[root@melksham ~]# cd /etc/init.d
[root@melksham init.d]# ./vsftpd start
Starting vsftpd for vsftpd: [ OK ]
|1633||Changing a screen saver from a web page (PHP, Perl, OSX)|
Here's a challenge. I want to change the screen saver on a mac mini, running OSX, from a browser anywhere in the world.
You may well ask why ... the screen of the mac mini is to be visible at Well House Manor where it will provide an information screen at the front door when it's not otherwise in ...
|1553||Automatic startup and shutdown of Tomcat|
Setting up Tomcat to shutdown and startup automatically when the Linux / Unix server restarts. The following is for Fedora Linux, with Tomcat installed at /usr/local/tomcat (probably via a symlink as taught on our deployment course). Server configuration - assuming a default run state of 3.
1. Copy ...
|1028||Linux / Unix - process priority and nice|
Visit certain theme parks, stand in queues for the rides. OK - that's fair enough at time. But then see folks with "fast pass" special tickets go the front and get, more or less, straight on. You may have seen the scenario ....But look carefully, and the operators never let the whole of the fast-track ...
|544||Repeating tasks with crontab|
Some things happen every day - or twice a day, or weekly ... in the background behind our web site - things like the rotation of log files, generation of reports and copying the Opentalk Forum into archives. We don't trigger these things manually!
On Unix and Linux systems, your crontab lets you set ...
Examples from our training material
|crontab|| Sample crontab file - repeated, timed jobs |
|timeset|| Sample crontab job - checking system clock|
You may download this module
as a sample of our material
Topics covered in this module
Provision of services via Daemons.
Controlling the startup and shutdown of Daemons.
Regular jobs via crontab.
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