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When debugging C code it is common to write debugging to an external text file using the __FILE__ and __LINE__ preprocessor defines to trace execution flow.

Unfortunately java does not support __FILE__ and __LINE__ but you can get the same functionality with this code which can be placed in one of your libraries.
	
public static void showTrace(String msg)
{
	if (msg.length() > 0) System.out.println(msg);
	System.out.println("Trace: " + 
				   "file " + new Throwable().getStackTrace()[1].getFileName() +
				   " class " + new Throwable().getStackTrace()[1].getClassName() +
				   " method " + new Throwable().getStackTrace()[1].getMethodName() +
				   " line " + new Throwable().getStackTrace()[1].getLineNumber());
}
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Found a nice subversion plugin for finder on the MAC.

The goal of the SCPlugin project is to integrate Subversion into the Mac OS X Finder. 

  • Support for Subversion.
  • Access to commonly used source control operations via contextual menu [screenshot]
  • Dynamic icon badging for files under version control. Shows the status of your files visually. [ screenshot ]
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After split brain has been detected, one node will always have the resource in a StandAlone connection state. The other might either also be in the StandAlone state (if both nodes detected the split brain simultaneously), or in WFConnection (if the peer tore down the connection before the other node had a chance to detect split brain).

At this point, unless you configured DRBD to automatically recover from split brain, you must manually intervene by selecting one node whose modifications will be discarded (this node is referred to as the split brain victim). This intervention is made with the following commands:

# drbdadm secondary resource 
# drbdadm disconnect resource
# drbdadm -- --discard-my-data connect resource


On the other node (the split brain survivor), if its connection state is also StandAlone, you would enter:

# drbdadm connect resource


You may omit this step if the node is already in the WFConnection state; it will then reconnect automatically.

If all else fails and the machines are still in a split-brain condition then on the secondary (backup) machine issue:

drbdadm invalidate resource
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System Requirements:
  • Minimum memory: 4MB
  • Minimum Diskspace: ~20MB
The Recital Runtime System (RTS) executes the object code generated by the Recital compiler. Object files are read from disk and loaded dynamically into shared memory segments. The advantage of this is that when an application has been loaded and is being run by one user, further users share the same object code in memory. This results in performance gains, reduced memory consumption and also provides a high degree of scalability for Recital applications.
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If you are running your Redhat/Centos or Fedora machine in an enterprise environment you may be sitting behind a network proxy server like squid.

If you try and update or install software it will fail with timeouts or errors contacting the repository mirrors.

To configure YUM to work with your proxy server you need to add the following line to your /etc/yum.conf file.

Anonymous proxy configuration:
proxy=http://yourproxyip:port/

If your proxy server requires authentication add the following lines to your /etc/yum.conf file instead.

proxy=http://yourproxyip:port/
proxy_username=youruser
proxy_password=yourpassword

 You will be able to update and install software now, give it a go!

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Recital Web: cookies, sessions, 64-bit Apache module: documentation update:

Recital Web Getting Started
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In this article Barry Mavin explains step by step how to setup a Linux HA (High Availability) cluster for the running of Recital applications on Redhat/Centos 5.3 although the general configuration should work for other linux versions with a few minor changes.

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In Linux you can run lsof and pipe it though grep for the files you are interested in, for example;
$ lsof | grep db.exe | grep accounts
db.exe    16897      john    6uw     REG      253,0    20012    3413872 /usr/recital100/qa/accounts.dbf
db.exe    16897      john    7u      REG      253,0     4176    3413885 /usr/recital100/qa/accounts.dbx
If you want to check for locks you can use lslk, for example;
$ lslk | grep db.exe | grep accounts
db.exe    16897 253,0 3413872 20012  w 0  0  0 12319   0 /usr/recital100/qa/accounts.dbf
If you don't have lslk installed you can install it with one of the updaters, for example on redhat linux:
$ yum update lslk

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Opening SSH to the outside world is a security risk. Here is how to restrict SSH access to certain IP addresses on a machine.

  1. Edit the /etc/hosts.allow file to include these lines, assuming your machine is on the 192.168.2.x nonrouting IP block, and you want to enable an external address of 217.40.111.121 IP block: Remember to add the period on the end of each incomplete IP number. If you have another complete IP address or range, add a space and that range on the end.

    sshd,sshdfwd-X11: 192.168.2. 217.40.111.121
  2. Edit your /etc/hosts.deny file to include this line:

    sshd,sshdfwd-X11:ALL 
  3. These lines refuse SSH connections from anyone not in the IP address blocks listed.

Additionally you can restrict SSH access by username.

  1. Edit the /etc/ssh/sshd_config file and add the following lines

    PermitRootLogin no
    AllowUsers      user1 user2 user3 etc
    PasswordAuthentication yes

Now restart the ssh daemon for these changes to take effect

service sshd restart




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Another useful article on IBM developerworks shows how to build PHP extensions using SWIG. You can find the article here.
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