Then add the user to the group

Helpers

Get a list of all existing users: $ cat /etc/passwd | cut -d: -f1

Get a list of all existing groups: $ cat /etc/group |cut -d: -f1

Running uWSGI with the right user and group

In this scenario, I use a socket to run my uWSGI instance. That socker must be located in a folder that have write access permission by your new user.

I’m using –uid and –gid to define the user & group that will run uWSGI. My –socket path is owned by my user. I’m running it with –master process so it can respawn processes if necessary.

Nginx setup with uWSGI

I started with a –no-site-packages virtualenv, so as not to use (or more  importantly depend) on any of the global site-packages.  Ok, cool.

First, I needed to install the python developer tools. (Use apt-get or aptitude, whatever floats your boat)

Then, I needed to install libjpeg and libjpeg-dev.  I’m not sure why, but I needed libjpeg simply doesn’t exist, so I needed to install libjpeg62.  I can’t pretend that I know the difference (or if there is one).  In fact, I may have gotten away with installing libjpeg62 and libjpeg-dev (rather than both “62″ versions… libjpeg62 and libjpeg62-dev), but only further testing will tell.

Why? If you install PIL without this library, you’ll get those wonderful “decoder jpeg not available” messages in Python.  Or worse yet, if you’re trying to use it in a Django, you may get some errors (specifically the “Upload a valid image. The file you uploaded was either not an image or a corrupted image” warning), or you may not get any until you open the shell.  Either way, you can test with the method listed below.  If you get the “decoder jpeg not available” message, your install didn’t work.

Check version installed of libjpeg:

lsof | grep libjpeg

The zlib package handles PNGs.

Alright, now we seem to be done with the prerequisites. Start your virtualenv (of course, myEnv in the example is the name of your virtualenv).

Download PIL and install.  This will make sure to install PIL within your virtualenv’s site-packages.

If you run into further problems (the “decoder jpeg not available” message again), you may have to resort to the long directions to get PIL and libjpeg to play happily together, but I hope not.

Now that you have everything installed, test it.  Open up a python shell from within your virtualenv.

Now try the following (with an image in your home directory) to see if everything is running smoothly.

If all of that works, you should now be ready to work.

Note: I would love to install the jpeg, freetype and zlib packages locally as well, but that was a step beyond what I was willing to mess with.  Maybe for a future set of instructions.

****

UPDATE:

In Ubuntu 11, it seems that you need libjpeg8-dev, rather than libjpeg62.
I have seen cases where multiple of PIL version are installed, under pyshared / pymodules / dist-packages. So PIL may work in the command line but not in mod_wsgi. It is important that only one version of PIL is running and preferably the one that work!

1. First of all, we need to create a username file: .hgrc

Include the following text:

Save it under you home folder eg:

This command should return the content of the file.

2. Go to your project folder

cd /my/folder

Start the repo:

hg init

* You can create a .hgignore file inside the .hg folder (make sure your hidden files are showing). This file will ignore a list of extension for example:

This will ignore Python compiled files and txt files.

3. Add project files to the repo:

or

hg addremove (if you set up your ignore file after the init)

4. Commit your work:

This will create a new commit, the message explained what has been added or modified.

5. Push you work to the repository:

I advice to create a file with default settings for convenience, which will stop you from entering the repo URL each time.

In the .hg folder, create a file called hgrc and put the following:

Then push:

It should be all set now.

This is a very basic startup guide, there’s many things you can do an option but that I recommend you check the Mercurial website: http://mercurial.selenic.com/

1. Create a new folder
2. cd to that folder

3. Run sphinx-quickstart

4. Generate documentation

Now you may wanna create a PDF out of your documentation:

I’m using Mac, so you will need to install MacTex (http://www.tug.org/mactex/)

Make sure that /usr/texbin get installed in your PATH, otherwise the make function would not work.

Check is it’s you path:

If not add it yourself:

If using Linux, follow this tutorial: http://jimmyg.org/blog/2009/sphinx-pdf-generation-with-latex.html

Once this is installed, run

Assuming you already have an existing domain (example.com) with the primary FTP user (jack) with password (schmidt) with home directory (/var/www/vhosts/example.com), and you wish to create additional ftp users (jill) with the same access privileges as jack to subfolder like this /var/www/vhosts/example.com/custom_folder (make sure the folder already exists) or to main folder (/var/www/vhosts/example.com). To do this follow the instructions below:

1. Login to shell with root access and issue this command:
# id jack
it will show something like that:
# uid=10002(jack) gid=2524(psacln) groups=2524(psacln)

2. remember the uid of jack which is 10002, we will need it later.

3. create user via the command below and use jack’s uid like this (this will let jill access subfolder):
# /usr/sbin/useradd -u 10002 -o -d /var/www/vhosts/example.com/custom_folder -g psacln -s /bin/false jill

4. create password for jill:
# passwd jill (enter the new password and confirm it, does not have to be the same as jack’s)

You should now be able to use an FTP client to login with that user’s name and password. This is the only good solution for Plesk for nowadays.

Setting up cron jobs in Unix and Solaris

cron is a unix, solaris utility that allows tasks to be automatically run in the background at regular intervals by the cron daemon. These tasks are often termed as cron jobs in unix , solaris.  Crontab (CRON TABle) is a file which contains the schedule of cron entries to be run and at specified times.

This document covers following aspects of Unix cron jobs
1. Crontab Restrictions
2. Crontab Commands
3. Crontab file – syntax
4. Crontab Example
5. Crontab Environment
6. Disable Email
7. Generate log file for crontab activity

1. Crontab Restrictions
You can execute crontab if your name appears in the file /usr/lib/cron/cron.allow. If that file does not exist, you can use
crontab if your name does not appear in the file /usr/lib/cron/cron.deny.
If only cron.deny exists and is empty, all users can use crontab. If neither file exists, only the root user can use crontab. The allow/deny files consist of one user name per line.

2. Crontab Commands

export EDITOR=vi ;to specify a editor to open crontab file.

crontab -e    Edit your crontab file, or create one if it doesn’t already exist.
crontab -l      Display your crontab file.
crontab -r      Remove your crontab file.
crontab -v      Display the last time you edited your crontab file. (This option is only available on a few systems.)

3. Crontab file
Crontab syntax :
A crontab file has five fields for specifying day , date and time followed by the command to be run at that interval.

*     *     *   *    *        command to be executed
-     -     -   -    -
|     |     |   |    |
|     |     |   |    +----- day of week (0 - 6) (Sunday=0)
|     |     |   +------- month (1 - 12)
|     |     +--------- day of        month (1 - 31)
|     +----------- hour (0 - 23)
+------------- min (0 - 59)

* in the value field above means all legal values as in braces for that column.
The value column can have a * or a list of elements separated by commas. An element is either a number in the ranges shown above or two numbers in the range separated by a hyphen (meaning an inclusive range).
Notes
A. ) Repeat pattern like /2 for every 2 minutes or /10 for every 10 minutes is not supported by all operating systems. If you try to use it and crontab complains it is probably not supported.

B.) The specification of days can be made in two fields: month day and weekday. If both are specified in an entry, they are cumulative meaning both of the entries will get executed .

4. Crontab Example
A line in crontab file like below removes the tmp files from /home/someuser/tmp each day at 6:30 PM.

30     18     *     *     *         rm /home/someuser/tmp/*

Changing the parameter values as below will cause this command to run at different time schedule below :

Note : If you inadvertently enter the crontab command with no argument(s), do not attempt to get out with Control-d. This removes all entries in your crontab file. Instead, exit with Control-c.

5. Crontab Environment
cron invokes the command from the user’s HOME directory with the shell, (/usr/bin/sh).
cron supplies a default environment for every shell, defining:
HOME=user’s-home-directory
LOGNAME=user’s-login-id
PATH=/usr/bin:/usr/sbin:.
SHELL=/usr/bin/sh

Users who desire to have their .profile executed must explicitly do so in the crontab entry or in a script called by the entry.

6. Disable Email
By default cron jobs sends a email to the user account executing the cronjob. If this is not needed put the following command At the end of the cron job line .

>/dev/null 2>&1

7. Generate log file
To collect the cron execution execution log in a file :

30 18 * * * rm /home/someuser/tmp/* > /home/someuser/cronlogs/clean_tmp_dir.log

This guide describes how to upgrade the standard PHP 5.1.x packages in CentOS 5.x 32-bit to the current development versions 5.2.x. These instructions were created using CentOS 5.3 32-bit and with the following PHP packages installed:

# rpm -qa |grep php

 php-common-5.1.6-15.el5.i386
 php-cli-5.1.6-15.el5.i386
 php-5.1.6-15.el5.i386
 php-pdo-5.1.6-15.el5.i386
 php-bcmath-5.1.6-15.el5.i386
 php-ldap-5.1.6-15.el5.i386
 php-devel-5.1.6-15.el5.i386
 php-gd-5.1.6-15.el5.i386
 php-xml-5.1.6-15.el5.i386
 php-mbstring-5.1.6-15.el5.i386
 php-mysql-5.1.6-15.el5.i386
 php-dba-5.1.6-15.el5.i386

As long as you’re using the standard PHP packages on your CentOS server you won’t need to do anything extra. If you’re using extra PHP packages that aren’t part of the standard CentOS repositories (like php-mcrypt) you’ll have to remove them or find updated versions of them.

Add the development repositories

First thing we need to do is add the development repositories to yum. When we add the development repository we’re going to configure it so it only pulls PHP packages. To start we’ll need create a new yum repository configuration file (use your favorite editor):

 # /etc/yum.repos.d/CentOS-Testing.repo

Copy/paste the following into this file:

  # CentOS-Testing:
  # !!!! CAUTION !!!!
  # This repository is a proving grounds for packages on their way to CentOSPlus and CentOS Extras.
  # They may or may not replace core CentOS packages, and are not guaranteed to function properly.
  # These packages build and install, but are waiting for feedback from testers as to
  # functionality and stability. Packages in this repository will come and go during the
  # development period, so it should not be left enabled or used on production systems without due
  # consideration.
  [c5-testing]
  name=CentOS-5 Testing
  baseurl=http://dev.centos.org/centos/$releasever/testing/$basearch/
  enabled=1
  gpgcheck=1
  gpgkey=http://dev.centos.org/centos/RPM-GPG-KEY-CentOS-testing
  includepkgs=php*

Make sure to remove any spaces at the start of each line, then save and close the file and you’re done.

Update PHP packages

Before updating your PHP packages you’ll want to get a list of what you currently have installed. To get a list of current PHP packages run the following:

 # rpm -qa |grep php

Now you can use yum to update the PHP packages on your system:

 # yum update

You should be shown a list of packages that are going to be updated. Compare it to the list of PHP packages on your system. Note any packages that are not in the list. You’ll need to remove these packages or find updates for them because they won’t work after you update to PHP 5.2.x. If that is acceptable type “y” to continue and let yum update the packages.

Once yum has completed restart Apache:

 # service httpd restart

To verify the update is working create a simple testing.php in your www directory with the following source code:

<?php
  phpinfo();
?>

and open it in a web browser. The new PHP version should be reflected at the top of the page.

Conclusion

You should now have PHP 5.2.6 running on CentOS 5.3 32-bit.

 # rpm -qa |grep php

  php-cli-5.2.6-2.el5s2
  php-mbstring-5.2.6-2.el5s2
  php-devel-5.2.6-2.el5s2
  php-pdo-5.2.6-2.el5s2
  php-gd-5.2.6-2.el5s2
  php-dba-5.2.6-2.el5s2
  php-common-5.2.6-2.el5s2
  php-bcmath-5.2.6-2.el5s2
  php-xml-5.2.6-2.el5s2
  php-pear-1.5.1-2.el5s2
  php-ldap-5.2.6-2.el5s2
  php-5.2.6-2.el5s2
  php-mysql-5.2.6-2.el5s2

 # php -v

  PHP 5.2.6 (cli) (built: Sep 15 2008 20:42:05)
  Copyright (c) 1997-2008 The PHP Group
  Zend Engine v2.2.0, Copyright (c) 1998-2008 Zend Technologies

Note: If your “php -v” output returns errors about PDO or JSON click here

Extras

Updating/Installing mcrypt

If you have php-mcrypt for PHP 5.1.x installed you’ll want to remove it:

Note: Your version number maybe different. Alter below command accordingly.

 rpm -e php-mcrypt-5.1.6-15.el5.centos.1

Download php-mcrypt for PHP 5.2.x and install it. You can find a 32-bit php-mcrypt package here FedoraJunkies.

Note: You’ll notice the “–nodeps” flag in the example. When you try to install php-mcrypt without it you get an error that php-common-5.2.6-2.el5s2 is missing even though it is installed.

 wget -c http://sourcemirrors.org/scotth/centos/5/php/php-mcrypt-5.2.6-2.i386.rpm
 rpm -i --nodeps php-mcrypt-5.2.6-2.i386.rpm

Restart Apache and you should now see mcrypt information on your testing.php page.

JSON and PDO being loaded twice

When you run the command “php -v” you might see the following errors:

 # php -v

  PHP Warning:  Module 'json' already loaded in Unknown on line 0
  PHP Warning:  Module 'PDO' already loaded in Unknown on line 0
  PHP 5.2.6 (cli) (built: Sep 15 2008 20:42:05)
  Copyright (c) 1997-2008 The PHP Group
  Zend Engine v2.2.0, Copyright (c) 1998-2008 Zend Technologies

This is caused by the following two lines in the /etc/php.ini file:

; Extension JSON
extension=json.so

; Extension PDO
extension=pdo.so

Comment out these lines by adding a “;” in front of “extension=”. These two modules are already loaded via these two files:

/etc/php.d/json.ini
/etc/php.d/pdo.ini