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Wednesday, August 11, 2010

Usage of #! /usr/bin/ksh..

I came across with below article for the usgae of #!/usr/bin/ksh.

Just Sharing....

Source : www

Originally, we only had one shell on unix. When you asked to run a command, the shell would attempt to invoke one of the exec() system calls on it. It the command was an executable, the exec would succeed and the command would run. If the exec() failed, the shell would not give up, instead it would try to interpet the command file as if it were a shell script.
Then unix got more shells and the situation became confused. Most folks would write scripts in one shell and type commands in another. And each shell had differing rules for feeding scripts to an interpreter.
This is when the "#! /" trick was invented. The idea was to let the kernel's exec() system calls succeed with shell scripts. When the kernel tries to exec() a file, it looks at the first 4 bytes which represent an integer called a magic number. This tells the kernel if it should try to run the file or not. So "#! /" was added to magic numbers that the kernel knows and it was extended to actually be able to run shell scripts by itself. But some people could not type "#! /", they kept leaving the space out. So the kernel was exended a bit again to allow "#!/" to work as a special 3 byte magic number.
So
#! /usr/bin/ksh
and
#!/usr/bin/ksh
now mean the same thing. I always use the former since at least some kernels might still exist that don't understand the latter.
And note that the first line is a signal to the kernel, and not to the shell. What happens now is that when shells try to run scripts via exec() they just succeed. And we never stumble on their various fallback schemes.

- Senior Unix SA

Tuesday, August 10, 2010

HVAR Technology for Replication..Server..

New Release of Replication Server Includes Patent Pending Technology for High Volume, Immediate Data Transfer Requirements


http://www.sybase.com/detail?id=1081513&contentOnly=true

Sybase, Inc., an SAP company (NYSE: SAP), and industry leader in delivering enterprise and mobile software, today announced transformative new features for the latest version of Sybase® Replication Server®, Sybase’s database replication product supporting change data capture, data distribution and synchronization of data across heterogeneous database environments for real-time analytics, reporting, distributed operations and disaster recovery. Sybase Replication Server innovation dramatically reduces latency with moving data between enterprise information stores, addressing challenges with the ever accelerating pace of business.

This latest release includes the following capabilities:

Real Time Loading for Sybase IQ – empowering organizations to deliver real-time analytics from ASE to Sybase IQ and through continuous change data capture (CDC) technology.

Advanced Performance Services – providing high-volume transaction replication using HVAR technology, significantly reducing transaction latency.

New Heterogeneous Capabilities – improving performance in heterogeneous database environments operating Sybase ASE, Oracle®, IBM® DB2® and Microsoft® SQL Server database servers, with parallel Data Server Interface (DSI). Enterprises can also now maintain warm standby applications for Oracle databases.

In-Memory Database Replication – enabling ASE on-disk databases to be replicated to ASE in-memory databases.

Cheers,

sybanva

Sybase Community Forum...

Hi All,

After long time, new posting...:(

Just sharing..may be some folks aware with it...Recently came across the Sybase's own  community forum, supported by Team Sybase....

Its having very good technical discussion, troubleshooting...tips fo ASE, IQ, Replication and many more...

http://www.sybase.com/detail_list?id=11507