August 2011

Linux / Unix : Difference betwen kill, pkill, kill -9 , pkill -9 command

Difference between kill and pkill command


kill -signal pid

DB2 : Difference between primary key and unique index


A relational database constraint. Primary key consists of one or more columns that uniquely identify a row in the table. For a normalized relation, there is one designated primary key.

Unique index

A physical object that stores only unique values. There can be one or more unique indexes on a table.

Difference between SYNONYM and ALIAS

SYNONYM: Synonym is dropped when the table or tablespace is dropped. Synonym is available only to the creator.

ALIAS: Alias is retained even if table or tablespace is dropped. ALIAS can be created even if the table does not exist. It is used mainly in distributed environment to hide the location info from programs. Alias is a global object & is available to all.

Unix : Packages - add ,check already installed, get details, remove Package

Software packages are group of files and directories. The software packages are grouped into cluster during the installation process. The cluster may have only one package or many depends upon the likely functionality packages.

In this article covers

1. How to add new package?
2. How to check the package is already installed or not?
3. How to get list of packages installed on the system?
4. How to get particular package details?
5. How to remove package and its all instances?

Perl Reference and Dereference

Reference Type How to Dereference
1. $refScalar=\$scalar; ${$refScalar}
2. $refArray=\@array; @{$refArray}
3. $refHash = \%hash %{$refHash}
4. $refFunction=\&function; &{$refFunction}

Unix : Patch - Install, remove, list

A patch is collection of files and directories to replace the existing file or directory for enchancement or error correction.

Linux / Unix Difference between who, whoami and who am i?


The who command helps to get the list of users who are all currently logged into the system.

for example:


JCL : Question Papers for freshers, experienced..

1)What does the disposition of (NEW,CATLG,KEEP) mean?

That this is a new dataset and needs to be allocated, to CATLG the dataset if the step is successful and to KEEP but not CATLG the dataset if the step abends. Thus if the step abends, the dataset would not be catalogued and we would need to supply the vol. ser the next time we refer to it.

2)What do you do if you do not want to keep all the space allocated to a dataset?

Selenium Testing - Firebox - selenium IDE for web testing

Selenium test scripts are widely used for web testing. Firebox have lots of plugins to add on functionality to it. Selenium IDE is one of the most popular firebox extension for selenium test scripts.

Selenium IDE mainly used to record and play back the steps, we do in browser. It gives us a integrated developement enviroment for selenium scripting.

JCL - Question Paper - Part II

1)What is the function of DD DISP parameter?

(1) Tells the system what to do with the dataset following normal termination of the step
(2) Describes the status of the dataset
(3) Tells the system what to do with the dataset following abnormal termination of the step

2)A DD statement has 2 types of parameters. Name them?


Positional, Keyword

3)How is the record format of an output dataset specified?

(Ans) RECFM parameter

4)How can unused space allocation be returned to the system when a dataset is closed?

(Ans) RLSE

5)What statement marks the beginning of a job step; assigns a name to the step; identifies the program or catalogued or in-stream procedure to be executed in the step?

(Ans) EXEC

6)How can a job send a status message to a TSO user at the completion of a job?

(Ans) NOTIFY - Ans

7)What is the function of a DD statement?

(Ans) Identifies & describes a dataset

8)What are the differences between JES2 & JES3?

(Ans) JES3 allocates datasets for all the steps before the job is scheduled. In JES2, allocation of datasets required by a step are done only just before the step executes.

9)What are the valid DSORG values?

(Ans) PS - QSAM, PO - Partitioned, IS - ISAM

10) How to change default proclib?


How do you run a COBOL batch program from a JCL? How do you run a COBOL/DB2 program?

To run a non DB2 program:


To run a DB2 program

Easytrieve: Merge two files

001000 //S030 EXEC PGM=EZTPA00

Oracle : How to change the password

There are two ways to change the password.

1. You can change the oracle password by using alter USER command like below

ALTER USER username IDENTIFIED BY newpassword

2. You can also change the password in SQL Plus using the PASSW command.

Oracle : Where to get the constraints details

To get the constraint details you can either use

1. user_constraints table
select * from user_constraints

If you know the table name then you can specify the condition to limit the result specific to table.

2. user_cons_columns

You can use this data dictionary view also to get the constraint details.

JCL Question papers - III

1)When space is allocated for an output dataset, what units can be used?

(Ans) Cylinders, Tracks, Blocks

2)A DD statement consists of 4 fields. Name them.

(Ans) Name, DD, parameter, comments

3)What is the purpose of the ‘DD KEYLEN’ parameter?

(Ans) Override the key length specified in the dataset label

4)What DD statement is used to supply the name of a dataset?

(Ans) Dsname

5)How ca

JCL Question papers - IV

1)Must tape dataset definitions include VOL=SER specifications?

(Ans) No

2)What statement can be used to send data to another MVS JES3 node?

(Ans) XMIT

3)How can the submitting user’s RACF authority be overridden in a job stream?

(Ans) Through the USER and PASSWORD parameter

4)Whatparameter of the job statement is used to limit the CPU time consumed by the job?

(Ans) TIME

Mobile Serial number IMEI - Is Mobile original or not?

IMEI used to identify the valid device by GSM... If you lost your mobile, you can still block it as mentioned in How to block your lost mobile

This even help to identify, your mobile is original or not. How to check this?

1. Just type *#06# in your mobile, it will display 15 digit IMEI in your screen. Make note of it.
2. Look at the 7th and 8th digit of it.
3. If it have the below combination then
00 - best quality mobile manufactured in original factory.
01 / 10 - Very good quality
02 / 20 / 13 - Very bad quality
08 / 80 - fair quality

Try check IMEI before buy it.

What is Android?

Android is mobile operating system. It is mainly for mobile devices such as mobile phones and tablet computers.

Android is open source. Android have mobile OS, Middleware, API's and applications. Android mobile OS is based on the linux kernel.

There are wide variety of android based application developements going on, mainly in java. Those gives additional functionality to android OS based mobile devices. If your mobile OS is android then you can download required application and can tailor as you like.

How to Safely Remove Hardware, If the Safely remove option not available in System Tray?

When we use USB drive, data cards..., we used to have option "Safely Remove Hardware" icon show up in the system tray.

Sometimes it is missing in my system tray. It is not adviced to unplug it before doing safely remove option. It will harm the device. So it makes me to shutdown the box to remove the USB drive safely. It pushed me to look at the way.

Windows: How to see the system information in command prompt?

Want to see the information like OS, OS version, OS configuration, OS build type, Product Id, BIOS version, Boot device, system model and so on in command prompt?

Just type systeminfo in command prompt, it takes a second and display the details like below format

Host Name:
OS Name:
OS Version:
OS Manufacturer:
OS Configuration:
OS Build Type:
Registered Owner:
Registered Organization:
Product ID:
Original Install Date:
System Boot Time:
System Manufacturer:
System Model:
System Type:
BIOS Version:
Windows Directory:
System Directory:
Boot Device:
System Locale:
Input Locale:
Time Zone:
Total Physical Memory:
Available Physical Memory:
Page File: Max Size:
Page File: Available:
Page File: In Use:
Page File Location(s):
Logon Server: